In article ,
Huge wrote:
CTEK ones are great, and designed to be used like this, and you can get
leads you permanently connect to the car ...

and ~£70.

My £6 one works just as well.

Sounds similar to the 14 quid Lidl one - except a lower peak output. The
Lidl one will charge an average battery overnight - then switch to
maintenance mode. Which is a lot lower than 13.8v. Can't remember the
exact figure - I'll try and check tomorrow.

However, 13.8v is what both my cars runs at when the battery is fully
charged. Which might be high for a constant trickle charge while parked up
- but obviously not when in use.

--
*How do they get the deer to cross at that yellow road sign?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Bill Wright wrote:
On 08/02/2018 14:22, Dave Plowman (News) wrote:

If you take a fairly normal (large) 75 amp hour battery, a drain of 1
amp would flatten it in 3 days.

No. Two days at most. You never get 75Ah out of a 75Ah battery.

Sounds like you've checked a poor battery. A good one will give you very
close to the figures I gave. But of course does depend what you take as
the terminal voltage before stopping.

The battery capacity figure is arrived at using the 20 hour rate - so a
higher discharge.

--
*You can't have everything, where would you put it?*

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.


NT

--
*Life is hard; then you nap

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
soup wrote:
[1] First the radio, then the power steering, then the speedo. Was
'great fun on the A71 with no power steering . My speed awareness is
crap, without a speedo, cars were queueing up behind me. Mind you didn't
want to go too fast with things stopping working .

First thing that showed on one of mine when the alternator failed - no
warning light came on - was the auto going into limp home mode and staying
in 3rd gear.

Since I was on my way to an important work thingie, the AA (after it
finally stopped) would only take it to an appointed garage since I wasn't
going with it. If I had, they'd have taken it and me home.

That ******* garage fitted a full price genuine makers new alternator and
a new battery too. The bill was enormous.

--
*Elephants are the only mammals that can't jump *

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 09 Feb 2018 01:00:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

They used inductors rather than the capacitor for tuning. I always
assumed it was to prevent microphonic effects due to the vibration on
the thin vanes.

Capacitance could be varied plunger style also, as indeed it was in
405 line TV's.

A capacitor would be more liable to drift or modulation due to side
to side motion, whereas an inductor would have to move longitudinally,
not a possibility with a stiff wire/ rod coupling to the pushbutton.

It's supposition really, but I cannot think of any other logical
reason for using the inductor to tune.


The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

Yes I remember some of the write ups a few years after, "if we hadn't
discovered transistors, what wonders would valve technology have
brought to us?"


AB

NT

On Thursday, 8 February 2018 11:53:08 UTC, F wrote:
I've SORNed my car as I'm not going to be able to drive it for a couple
of months. No doubt the battery will eventually need a charge but do I
really have to disconnect it as current [pun not intended] advice seems
to indicate? If I do, I will, no doubt, have a whole lot of setting up
to do on the various electronics.

It's many moons since I last charged a car battery and at that time I
just clamped the charger leads on and let it get on with it.

--
F

Put the charger on a plug in timer set for say a half/quarter hour per day.

On 09/02/2018 00:51, Dave Plowman (News) wrote:
In article ,
Huge wrote:
CTEK ones are great, and designed to be used like this, and you can get
leads you permanently connect to the car ...

and ~£70.


I think mine was a good bit less than that...

My £6 one works just as well.


......but not that cheap :-/

Sounds similar to the 14 quid Lidl one - except a lower peak output. The
Lidl one will charge an average battery overnight - then switch to
maintenance mode. Which is a lot lower than 13.8v. Can't remember the
exact figure - I'll try and check tomorrow.

However, 13.8v is what both my cars runs at when the battery is fully
charged. Which might be high for a constant trickle charge while parked up
- but obviously not when in use.

I looked out for the Lidl ones but they weren't about when I needed one :-(

In message , Archibald
Tarquin Blenkinsopp writes
On Fri, 09 Feb 2018 01:00:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all
the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

They used inductors rather than the capacitor for tuning. I always
assumed it was to prevent microphonic effects due to the vibration on
the thin vanes.

Capacitance could be varied plunger style also, as indeed it was in
405 line TV's.

A capacitor would be more liable to drift or modulation due to side
to side motion, whereas an inductor would have to move longitudinally,
not a possibility with a stiff wire/ rod coupling to the pushbutton.

It's supposition really, but I cannot think of any other logical
reason for using the inductor to tune.


The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

Yes I remember some of the write ups a few years after, "if we hadn't
discovered transistors, what wonders would valve technology have
brought to us?"

I believe (though possibly incorrectly) that the advantage of inductor
tuning makes it easier to accommodate the capacitance of the aerial coax
at HF end of MW and LW. It also avoids the inevitable capacitive
'pot-down', and increases the sensitivity at the HF end.

--
Ian

On Fri, 9 Feb 2018 08:58:42 +0000, Ian Jackson
wrote:

In message , Archibald
Tarquin Blenkinsopp writes
On Fri, 09 Feb 2018 01:00:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all
the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

They used inductors rather than the capacitor for tuning. I always
assumed it was to prevent microphonic effects due to the vibration on
the thin vanes.

Capacitance could be varied plunger style also, as indeed it was in
405 line TV's.

A capacitor would be more liable to drift or modulation due to side
to side motion, whereas an inductor would have to move longitudinally,
not a possibility with a stiff wire/ rod coupling to the pushbutton.

It's supposition really, but I cannot think of any other logical
reason for using the inductor to tune.


The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

Yes I remember some of the write ups a few years after, "if we hadn't
discovered transistors, what wonders would valve technology have
brought to us?"

I believe (though possibly incorrectly) that the advantage of inductor
tuning makes it easier to accommodate the capacitance of the aerial coax
at HF end of MW and LW. It also avoids the inevitable capacitive
'pot-down', and increases the sensitivity at the HF end.

I don't understand. It's a long time since I played with wireless, but
surely the cable capacitance isn't a factor. Whether the final
matching is done by L or C, the coax is just a fixed impedance?

I recollect that there used to be trimmers and padders in the tuned
circuits, but these were to maintain "tracking" between the higher
frequency mixer oscillator and the aerial tank circuit.

I cannot see that this system of tracking would alter even if the
inductor became the new variable.

The sensitivity would be poor if the tracking were out, as the RF tank
circuit would no longer be at maximum output when set to a station 470
kHz away from the mixer.

The term "pot down" means nothing to me, but it is a long while.....

I tried a quick search, but couldn't find anything. Could you
enlighten?

Sadly a lot of the brain cells that accompanied me on my journey
through consumer electronics are now ossified :-(

Regards

AB

On Friday, 9 February 2018 01:01:10 UTC, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

those tuners were standard in B&W TVs for a long time. Not a turret tuner, I can't remember the name. OK until there are more radio stations, then you wish for a simple knob.

The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

That's what mine is, a basic 1 transistor class A amp.


NT

On 09/02/18 10:20, wrote:
On Friday, 9 February 2018 01:01:10 UTC, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

those tuners were standard in B&W TVs for a long time. Not a turret tuner, I can't remember the name. OK until there are more radio stations, then you wish for a simple knob.

The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

That's what mine is, a basic 1 transistor class A amp.


Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

It took really a lot of transformer to do push pull before NPN
transistors came along, and then of course no transformers at all became
the norm...








NT



--
"If you dont read the news paper, you are un-informed. If you read the
news paper, you are mis-informed."

Mark Twain

In article ,
harry wrote:
On Thursday, 8 February 2018 11:53:08 UTC, F wrote:
I've SORNed my car as I'm not going to be able to drive it for a couple
of months. No doubt the battery will eventually need a charge but do I
really have to disconnect it as current [pun not intended] advice seems
to indicate? If I do, I will, no doubt, have a whole lot of setting up
to do on the various electronics.

It's many moons since I last charged a car battery and at that time I
just clamped the charger leads on and let it get on with it.

--
F

Put the charger on a plug in timer set for say a half/quarter hour per day.

There is zero need to charge it every day. Once a week would be more than
enough. With a charger which either switches off when fully charged, or
goes to a maintenance mode.

--
*I started out with nothing... and I still have most of it.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Chris Bartram wrote:
I looked out for the Lidl ones but they weren't about when I needed one :-(

Same as all Lidl tools, you have to buy when on offer. And depending on
the store/item can sell out very quickly.

--
*If love is blind, why is lingerie so popular? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article b032ddcf-aa49-4fc1-bb7c-8c6128ebc3a9
@googlegroups.com, says...

Older ones ... had valves. And at least some proudly
declared 'transistor' on the front regardless.


The process of evolution was the development of valves that
would work with an HT of only 12 volts, rather than the normal
200 - 250V, so that a vibrator was no longer needed for all
the small signal stages.

The only thing that wouldn't work @ 12V was the output valve
which drove the loudspeaker but, by this time, power
transistors capable of doing the job had been developed so one
of those was used to drive the loudspeaker instead.

So the word Transistor (in the singular, as you posted, was
100% correct!

The first TV that PYE sold claiming to be 'transistorised' had
one transistor - used as sync separator, IIRC - but everything
else remained valve driven. You might call that a sales
gimmick - and you would be right - but the car radio was a
genuine way of operating a car radio from 12V without any
complicated high voltage generation required and was a real
advance.

--

Terry

---
This email has been checked for viruses by AVG.
http://www.avg.com

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

In message , Archibald
Tarquin Blenkinsopp writes
On Fri, 9 Feb 2018 08:58:42 +0000, Ian Jackson
wrote:

In message , Archibald
Tarquin Blenkinsopp writes
On Fri, 09 Feb 2018 01:00:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all
the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

They used inductors rather than the capacitor for tuning. I always
assumed it was to prevent microphonic effects due to the vibration on
the thin vanes.

Capacitance could be varied plunger style also, as indeed it was in
405 line TV's.

A capacitor would be more liable to drift or modulation due to side
to side motion, whereas an inductor would have to move longitudinally,
not a possibility with a stiff wire/ rod coupling to the pushbutton.

It's supposition really, but I cannot think of any other logical
reason for using the inductor to tune.


The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

Yes I remember some of the write ups a few years after, "if we hadn't
discovered transistors, what wonders would valve technology have
brought to us?"

I believe (though possibly incorrectly) that the advantage of inductor
tuning makes it easier to accommodate the capacitance of the aerial coax
at HF end of MW and LW. It also avoids the inevitable capacitive
'pot-down', and increases the sensitivity at the HF end.

I don't understand. It's a long time since I played with wireless, but
surely the cable capacitance isn't a factor. Whether the final
matching is done by L or C, the coax is just a fixed impedance?

I recollect that there used to be trimmers and padders in the tuned
circuits, but these were to maintain "tracking" between the higher
frequency mixer oscillator and the aerial tank circuit.

I cannot see that this system of tracking would alter even if the
inductor became the new variable.

The sensitivity would be poor if the tracking were out, as the RF tank
circuit would no longer be at maximum output when set to a station 470
kHz away from the mixer.

The term "pot down" means nothing to me, but it is a long while.....

I tried a quick search, but couldn't find anything. Could you
enlighten?

Sadly a lot of the brain cells that accompanied me on my journey
through consumer electronics are now ossified :-(

'Pot-down' is shorthand jargon for 'reducing the voltage by means of a
potential divider'.

If the radio is capacitor-tuned, there is invariably a certain amount of
residual stray capacitance when the vanes are at minimum. This will
'pot-down' the voltage coming another capacitive source - ie the signal
voltage being delivered from the aerial and screened high-impedance
coaxial lead. To allow for differing lengths of lead, old radios
invariably needed a user tweakable trimmer which was used to peak up the
signal at the HF end - and, depending on how good the tracking was, this
held reasonably good across the whole of the tuning range. As I said, I
believe that with inductor tuning, there is less of the inevitable
capacitive 'pot-down' effect - which makes the radio a bit more
sensitive - but don't take my word for it!

However, I also guess that as the variable tuning capacitor for typical
MW and LW radio was a physically large 500pF. As most car radios had an
RF stage, this would have required it to be 3-gang - so inductive would
require a lot less space, and cost a lot less. [Somewhere, I've got an
old LW/MW car radio, and I'm sure it has three tuning slugs (like
pistons, driven by a rotating cam.]




--
Ian

In message , "Dave Plowman (News)"
writes
In article ,
harry wrote:
On Thursday, 8 February 2018 11:53:08 UTC, F wrote:
I've SORNed my car as I'm not going to be able to drive it for a couple
of months. No doubt the battery will eventually need a charge but do I
really have to disconnect it as current [pun not intended] advice seems
to indicate? If I do, I will, no doubt, have a whole lot of setting up
to do on the various electronics.

It's many moons since I last charged a car battery and at that time I
just clamped the charger leads on and let it get on with it.

--
F

Put the charger on a plug in timer set for say a half/quarter hour per day.

There is zero need to charge it every day. Once a week would be more than
enough. With a charger which either switches off when fully charged, or
goes to a maintenance mode.

Indeed. Car batteries are certainly not 'snowflakes' (if I may be
excused for using a presently-fashionable word), and are designed to
have a hard life. A quick burst from any charger once in a while should
be sufficient to ensure it's OK when you really need it.
--
Ian

In article ,
The Natural Philosopher wrote:
It took really a lot of transformer to do push pull before NPN
transistors came along, and then of course no transformers at all became
the norm...

A lot of transformer? Is that code for something?

Just a driver and output, to allow the same transistor to be used.

--
*I'm not a paranoid, deranged millionaire. Dammit, I'm a billionaire.

Dave Plowman London SW
To e-mail, change noise into sound.

On 09/02/18 10:58, Ian Jackson wrote:
However, I also guess that as the variable tuning capacitor for typical
MW and LW radio was a physically large 500pF. As most car radios had an
RF stage, this would have required it to be 3-gang

2 gang.

MW/LW switched both one RF coils AND local oscillator coils

But ONLY those two.

In practice tuning the EF stage in mots conmmnercial grade sets was
really veryt briad - the [promary function is image regjection at
900Khz- 940Khz away from the incoming signla. On LW that really meant
so far away you didnt need to worry so the oinly thing te RF tuning did
a bit of was a slight gain to the incoming signal (mostly noise on LW
anyway)

With superhets neartl ALL te selectivey is in et pretuned fixed
frequeancy IF strip, and thats why they were de regeur. The only tuning
as the local oscillator. The RF srages might not even be PRESENT let
alone tuned - direct injection into te micxer was not that uncommon
spcially on ferrite rod tuned portables but was frowned upon a little as
it pumped the oslitaor back up the aerial.

So in essence the RF stage MOSTLY stoppoed te oscillatort being
rtertsnmitted , andf provided sa bit of gsaiun., It made very little
difference to selectivity and was pretty low Q really.

Ther was no need for two RF coils.

--
The biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.

You were quite correct in your previous post regarding the
elimination of vibrating variable capacitor vanes.

The tuning and preset tuning arrangements were fiendishly
clever and difficult to describe but probably not too
expensive to build in quantity. I haven't seen one of these
radios for nearly 50 years, so bear with me if this
description is not 100% correct!

The cores were connected to a swivelling plate or tuning bar
which rotated through about 90°. This was also connected by
simple mechanical linkage to the dial pointer. This entire
assembly could be moved from one end of the band to the other
with very little pressure.

The main and preset tuning were all accomplished by bringing
the flat edge of a semi-circular metal disc into contact with
the tuning bar which would the swivel until its face exactly
matched the angle of the flat.

The disc for the main tuning was normally held in contact with
the bar and connected to the tuning kbob via a worm gear. This
held the entire assembly in place and ensured that the tuning
point was vibration proof.

The discs for the presets were normally held away from the
tuning bar. Also, the position of each disc, including the
main one, was held in place by a simple friction clutch.


When it was desired to preset a button to the current tuning
point, the button was pulled out. This caused the cluth for
its disc to be released and the disc moved forwards so that it
was in intimate contact with the tuning bar: thus it rotated
to match it.

When the button was released, the cluth re-engaged and the
disc withdrew.

To return to a stored position, the button was pushed in. This
released the main tuning clutch, freeing up the mechanism, and
the button's disc was pushed forward onto the tuning bar which
promptly aligned itself to the stored position.

The presets also operated the wavechange switch, the righthand
button being assigned to Long Wave and the others to Medium
Wave.

--

Terry

---
This email has been checked for viruses by AVG.
http://www.avg.com

On 9 Feb 2018 11:08:23 GMT, Huge wrote:

snip

Indeed. Car batteries are certainly not 'snowflakes' (if I may be
excused for using a presently-fashionable word), and are designed to
have a hard life.

Although running them flat is guaranteed to kill them, since they are
not designed to survive this.

Correct. Even discharging a deep discharge LA battery to 50% capacity
or more will effect it's cycle life.

That's why "leisure" batteries exist.

They are no more able to survive being run flat (especially for a
prolonged period) than any other LA battery.

The main difference between an SLI and leisure / traction battery is
the thickness of the plates and hence the capacity / kg.

Cheers, T i m

On Friday, 9 February 2018 10:43:31 UTC, Terry Casey wrote:
In article b032ddcf-aa49-4fc1-bb7c-8c6128ebc3a9
@googlegroups.com, tabbypurr says...

Older ones ... had valves. And at least some proudly
declared 'transistor' on the front regardless.


The process of evolution was the development of valves that
would work with an HT of only 12 volts, rather than the normal
200 - 250V, so that a vibrator was no longer needed for all
the small signal stages.

The only thing that wouldn't work @ 12V was the output valve
which drove the loudspeaker but, by this time, power
transistors capable of doing the job had been developed so one
of those was used to drive the loudspeaker instead.

So the word Transistor (in the singular, as you posted, was
100% correct!

The first TV that PYE sold claiming to be 'transistorised' had
one transistor - used as sync separator, IIRC - but everything
else remained valve driven. You might call that a sales
gimmick - and you would be right - but the car radio was a
genuine way of operating a car radio from 12V without any
complicated high voltage generation required and was a real
advance.

correct yes, just very misleading.
The one odd thing about it was that the output tran ran cold. Not what I'd expect for a class A output.

The other end of tv development was when they were all transistor except for the LOPT valve.


NT

In message , The Natural Philosopher
writes
On 09/02/18 10:58, Ian Jackson wrote:
However, I also guess that as the variable tuning capacitor for
typical MW and LW radio was a physically large 500pF. As most car
radios had an RF stage, this would have required it to be 3-gang

2 gang.

3-gang - surely? RF stage input, RF stage output / mixer input, and
local oscillator.

MW/LW switched both one RF coils AND local oscillator coils

But ONLY those two.

Uh?

In practice tuning the EF stage in mots conmmnercial grade sets was
really veryt briad - the [promary function is image regjection at
900Khz- 940Khz away from the incoming signla. On LW that really meant
so far away you didnt need to worry so the oinly thing te RF tuning did
a bit of was a slight gain to the incoming signal (mostly noise on LW
anyway)

With superhets neartl ALL te selectivey is in et pretuned fixed
frequeancy IF strip, and thats why they were de regeur.

Well..... quite. That's what superhets do. [When was the last time you
used a TRF set ?]

The only tuning as the local oscillator. The RF srages might not even
be PRESENT let alone tuned

Most house/portable LW/MW radios don't have an RF stage [RF stage?
LUXURY!] - but the aerial/mixer input is invariably tuned (as close as
possible) to the signal frequency, and the local oscillator runs the IF
frequency above the signal frequency.

- direct injection into te micxer was not that uncommon spcially on
ferrite rod tuned portables but was frowned upon a little as it pumped
the oslitaor back up the aerial.

You don't get much local oscillator radiation if the set has a ferrite
rod aerial.

So in essence the RF stage MOSTLY stoppoed te oscillatort being
rtertsnmitted , andf provided sa bit of gsaiun., It made very little
difference to selectivity and was pretty low Q really.

Ther was no need for two RF coils.

It all depends on the application. LW/MW car radio are VERY short, and
I'm pretty sure that many had an RF stage to boost the sensitivity. With
those old types (with the 'peak-it-at-the-HF-end' trimmer) it was
obvious that the input tuning was quite sharp (and therefore critical if
you wanted to optimise sensitivity). However, I have a couple of 'more
modern' sets that don't seem to have any provision for LW/MW peaking -
and both seem to work OK when fed with a short vertical loft aerial in
the loft, via about 15' of 75 ohm coax. With the old sets, this would
have been a killer - so I'm not sure what the input circuit is like.
--
Ian

On Fri, 9 Feb 2018 10:58:08 +0000, Ian Jackson
wrote:

In message , Archibald
Tarquin Blenkinsopp writes
On Fri, 9 Feb 2018 08:58:42 +0000, Ian Jackson
wrote:

In message , Archibald
Tarquin Blenkinsopp writes
On Fri, 09 Feb 2018 01:00:22 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
wrote:
On Thursday, 8 February 2018 19:03:05 UTC, Chris Green wrote:
"Dave Plowman (News)" wrote:

On a modern car you might be amazed how much is powered up all
the time.
My radio retains its station memory etc even if totally powered down.

Which doesn't actually need any power, flash memory retains its
contents with no power. Older radios used to use powered memory to
retain things but I'm not sure that modern ones do.

Older ones didn't have memories, they had valves. And at least some
proudly declared 'transistor' on the front regardless.

A decent one had a very clever push button system which did just the same
job as a station memory. But must have cost a fortune to make.

They used inductors rather than the capacitor for tuning. I always
assumed it was to prevent microphonic effects due to the vibration on
the thin vanes.

Capacitance could be varied plunger style also, as indeed it was in
405 line TV's.

A capacitor would be more liable to drift or modulation due to side
to side motion, whereas an inductor would have to move longitudinally,
not a possibility with a stiff wire/ rod coupling to the pushbutton.

It's supposition really, but I cannot think of any other logical
reason for using the inductor to tune.


The were hybrid ones which used a transistor power amp and 12v HT for the
RF valves. Getting rid of that irritating vibrator.

Yes I remember some of the write ups a few years after, "if we hadn't
discovered transistors, what wonders would valve technology have
brought to us?"

I believe (though possibly incorrectly) that the advantage of inductor
tuning makes it easier to accommodate the capacitance of the aerial coax
at HF end of MW and LW. It also avoids the inevitable capacitive
'pot-down', and increases the sensitivity at the HF end.

I don't understand. It's a long time since I played with wireless, but
surely the cable capacitance isn't a factor. Whether the final
matching is done by L or C, the coax is just a fixed impedance?

I recollect that there used to be trimmers and padders in the tuned
circuits, but these were to maintain "tracking" between the higher
frequency mixer oscillator and the aerial tank circuit.

I cannot see that this system of tracking would alter even if the
inductor became the new variable.

The sensitivity would be poor if the tracking were out, as the RF tank
circuit would no longer be at maximum output when set to a station 470
kHz away from the mixer.

The term "pot down" means nothing to me, but it is a long while.....

I tried a quick search, but couldn't find anything. Could you
enlighten?

Sadly a lot of the brain cells that accompanied me on my journey
through consumer electronics are now ossified :-(

'Pot-down' is shorthand jargon for 'reducing the voltage by means of a
potential divider'.

If the radio is capacitor-tuned, there is invariably a certain amount of
residual stray capacitance when the vanes are at minimum. This will
'pot-down' the voltage coming another capacitive source - ie the signal
voltage being delivered from the aerial and screened high-impedance
coaxial lead. To allow for differing lengths of lead, old radios
invariably needed a user tweakable trimmer which was used to peak up the
signal at the HF end - and, depending on how good the tracking was, this
held reasonably good across the whole of the tuning range.

The cable impedance was 75 Ohms, but the aerial would be a total
mismatch. The trimmer seems logical, Strange I never really thought
about it, but every radio had that little hole inviting the insertion
of a screwdriver :-)

As I said, I
believe that with inductor tuning, there is less of the inevitable
capacitive 'pot-down' effect - which makes the radio a bit more
sensitive - but don't take my word for it!

However, I also guess that as the variable tuning capacitor for typical
MW and LW radio was a physically large 500pF.
Of course! I remember now, all the tuning caps were air spaced. They
were damned big.

It was many years later that the addition of a polymer as a dielectric
gave them a bigger puffage. Manufacturing techniches probably helped
too. I recollect that the early ones needed the skills of the local
bike shop to get them "trued up".

I also seem to recall a description of a high Voltage being used to
clear shorts when the plates brushed together.

DAB wirelesses don't really make up for all the fun times lost :-)


Incidentally, on the subject of tuning caps, were you aware of any
drift related to atmospheric humidity?

Shaw moisture meters were a standard in many industries and
laboratories all over the world. The probes were and still are for
most manufacturers made from aluminium/ aluminium oxide i.e a
capacitor with an oxide dielectric.

There was a photo of "old man Shaw", the company founder outside his
wireless repair shop.

I suspect the two enterprises had a link additional to the owner?

Certainly it often crossed my mind over the years.



As most car radios had an
RF stage, this would have required it to be 3-gang - so inductive would
require a lot less space, and cost a lot less. [Somewhere, I've got an
old LW/MW car radio, and I'm sure it has three tuning slugs (like
pistons, driven by a rotating cam.]


Wonder if it will be possible to buy a "dash top box" when analogue
wireless is phased out :-)

Regards

& Thanks for the memories

AB

On 9 Feb 2018 10:44:10 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!

An ECC82 perchance?

A nice little double triode, albeit with a heater supply that could
trap the unwary.

I had an ambition to build a Mullard 5:10, but like walking the
Pennine way, it wont happen :-(

AB

On Fri, 9 Feb 2018 10:43:29 -0000, Terry Casey
wrote:

In article b032ddcf-aa49-4fc1-bb7c-8c6128ebc3a9
, says...

Older ones ... had valves. And at least some proudly
declared 'transistor' on the front regardless.


The process of evolution was the development of valves that
would work with an HT of only 12 volts, rather than the normal
200 - 250V, so that a vibrator was no longer needed for all
the small signal stages.

The only thing that wouldn't work @ 12V was the output valve
which drove the loudspeaker but, by this time, power
transistors capable of doing the job had been developed so one
of those was used to drive the loudspeaker instead.

So the word Transistor (in the singular, as you posted, was
100% correct!

The first TV that PYE sold claiming to be 'transistorised' had
one transistor - used as sync separator, IIRC - but everything
else remained valve driven. You might call that a sales
gimmick - and you would be right - but the car radio was a
genuine way of operating a car radio from 12V without any
complicated high voltage generation required and was a real
advance.

That wasn't the abortion that was produced as a dual standard was it?

I never saw the transistor mod, but the sync was an absolute
nightmare.

The amount of line tearing was a complex relationship of image
transmitted times mutipath echos. Even with a totally clean signal
some tearing would occur.

A transistor would be a good move given the space needed, but deriving
the supply must have been interesting.

I cannot think of any other Pye that could qualify for the mod, didn't
they become Phillips after that Dual standard model?

AB

On Fri, 09 Feb 2018 15:50:07 +0000, Archibald Tarquin Blenkinsopp wrote:

On 9 Feb 2018 10:44:10 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!

An ECC82 perchance?

A nice little double triode, albeit with a heater supply that could trap
the unwary.

No, I think they were EL84s.


--
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On Fri, 09 Feb 2018 15:50:07 +0000, Archibald Tarquin Blenkinsopp wrote:

On 9 Feb 2018 10:44:10 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!

An ECC82 perchance?

I built my first radio using DF96, DAF96, DK96 and DL96 (I think).

--
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wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
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On 9 Feb 2018 16:27:21 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 15:50:07 +0000, Archibald Tarquin Blenkinsopp wrote:

On 9 Feb 2018 10:44:10 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!

An ECC82 perchance?

A nice little double triode, albeit with a heater supply that could trap
the unwary.

No, I think they were EL84s.

The EL84 was a pentode. It was possible to use one of these as a stand
alone amp, but it was only really practical with a crystal cartridge,
or similar,

A preamp to boost the signal was often developed using an ECC82, with
one or both stages being used. The gain would still probably not be
high enough for a quality magnetic, so the lineup became Ef86 preamp,
ecc82 phase splitter and two EL84s

Happy days!

http://www.valve-radio.co.uk/wp-cont...013/11/101.jpg

Sadly the mind is going, at one time I would have known what C13 and
R22 did. :-(

AB

On 9 Feb 2018 16:28:34 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 15:50:07 +0000, Archibald Tarquin Blenkinsopp wrote:

On 9 Feb 2018 10:44:10 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!

An ECC82 perchance?

I built my first radio using DF96, DAF96, DK96 and DL96 (I think).

It sounds right, with a 90V Ever ready?

Was the heater supply a separate battery? I suppose it must have been.

The Ht battery was made of pp3 type cells. Must have been 60 of them.
Damned expensive way of boiling electrons :-)

I used the cases of the commercially available ones as toolboxes for a
few years.

I don't think that there were any valve radios produced when I entered
consumer electronics.

My first wireless after the almost compulsory xtal set was a TRF with
feedback, [regenerative]. It was transistorised, and very good. I can
understand why they never were generally available to the public
though.

AB

In article ,
Archibald Tarquin Blenkinsopp wrote:
If the radio is capacitor-tuned, there is invariably a certain amount of
residual stray capacitance when the vanes are at minimum. This will
'pot-down' the voltage coming another capacitive source - ie the signal
voltage being delivered from the aerial and screened high-impedance
coaxial lead. To allow for differing lengths of lead, old radios
invariably needed a user tweakable trimmer which was used to peak up the
signal at the HF end - and, depending on how good the tracking was, this
held reasonably good across the whole of the tuning range.

The cable impedance was 75 Ohms, but the aerial would be a total
mismatch. The trimmer seems logical, Strange I never really thought
about it, but every radio had that little hole inviting the insertion
of a screwdriver :-)

I don't think the theoretical cable impedance was 75 ohms on a car radio
aerial. It was peculiar stuff with a spiral inner core. 300 ohms is the
figure in my mind - but could be wrong.

IIRC, more modern radios match to the aerial automatically.

--
*It is easier to get older than it is to get wiser.

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 08 Feb 2018 22:27:37 +0000 (GMT)
charles wrote:

my Citroen C5 used to warn that the battery was getting low and
certain functions would be switched off,

How technology has advanced - I once forgot to reconnect the alternator
after I'd done some welding on my Mini - it ran fine for a while but
then it started to misfire and the lights were dimming. It stalled
once and I managed to bump start it, but the second time it just died
completely. Fortunately I wasn't far from home so I walked back and
got a bike to collect the battery and charge it.
I think I still prefer the simplicity of a 1950s car to the cleverness
of a modern one, although traction control and ABS are quite good.
Replacing the points is a lot easier than troubleshooting an ECU and
its attendant sensors, if you only have a screwdriver.

On Fri, 09 Feb 2018 10:43:16 +0000 (GMT)
"Dave Plowman (News)" wrote:

In article ,
Chris Bartram wrote:
I looked out for the Lidl ones but they weren't about when I needed
one :-(

Same as all Lidl tools, you have to buy when on offer. And depending
on the store/item can sell out very quickly.

I've taken to buying small "useful" DIY items in Lidl even though I
don't need them just now, because I might later. I wonder how many of
them will just sit on a shelf unused.

On 09/02/2018 16:54, Archibald Tarquin Blenkinsopp wrote:
On 9 Feb 2018 16:28:34 GMT, Bob Eager wrote:

I built my first radio using DF96, DAF96, DK96 and DL96 (I think).

It sounds right, with a 90V Ever ready?

Was the heater supply a separate battery? I suppose it must have been.

Some batteries for valve portables had the LT and HT in the same unit
for simplicity - presumably the LT one was a single zinc/carbon cell
rather than the layer construction used for HT.

My first wireless after the almost compulsory xtal set was a TRF with
feedback, [regenerative]. It was transistorised, and very good. I can
understand why they never were generally available to the public
though.

Kit transistor radios were often regenerative to avoid the difficulty of
alignment of a superhet, which would require a signal generator.

Up to about the early 1930s domestic (valve) radios were regenerative
with a 'reaction' control (variable capacitor). People just got used to
increasing the reaction until it squealed and turning it back a bit.
Apparently you could tell when other people were tuning in in the
evening by the interference to other sets.

Earlier TRF sets had two tuning controls which you had to turn together
as they couldn't make twin gangs that tracked accurately enough.

--
Max Demian

In article ,
says...


I don't think the theoretical cable impedance was 75 ohms on a car radio
aerial. It was peculiar stuff with a spiral inner core. 300 ohms is the
figure in my mind - but could be wrong.


You are quite right about it most definitely NOT being 75 ohm
cable, Dave - the most important thing about it was that it
was very low capacity. We managed to get a reel of it from
PYE's spares/component wing, the only place we could find it,
as we lat lots of requests from customers for it - I think
there was an outbreak of 'must have the aerial on thre back,
for some reason, so we were always being asked for extension
leads.

Rather than a spiral, the very fine centre conductor was
formed into a zig-zag with a long zig and a short zag - I hope
you get my meaning! - which ran inside a fairly rigid clear
plastic tube with the screening surrounding that. The zig-zag
kept the wire as close to the centre of the tube for as much
of its length as possible to maintain the low capacity.

The cable supplied with the aerial formed part of the input
tuned circuit, with the low value trimmer being used to
balance the exact capacity of the cable. Exceeding the length
of the cable increased the total capacitance so that it was
outside the range of adjustment, so this had to be addressed.

Fortunately we knew the capacitance of the cable per metre, so
we could easily work out what the total capacitance of the
entire run would be and calculate the value of a series
capacitor so that the radio would see the correct figure.

Egen made some very nice plugs and line sockets with similar
caps and cable clamps to a normal coax plug, so we were able
to solder a sufflex capacitor of the right value onto the end
of the centre conductor and clamp the plug in the normal way.

The sufflex capacitor sat neatly inside the body of the plug
with its other wire potruding from the centre pin so all we
had to do to complete the job was to solder and trim this
wire.



--

Terry

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In article ,
says...


On Fri, 09 Feb 2018 15:50:07 +0000, Archibald Tarquin Blenkinsopp wrote:

Happy days!

http://www.valve-radio.co.uk/wp-cont...013/11/101.jpg

Sadly the mind is going, at one time I would have known what C13 and
R22 did. :-(



The original data on the 5-10 as published by Mullard is he

http://www.r-type.org/articles/art-003e.htm

It says that: A CR network (C1, R1) [C13 and R22 in your
version of the circuit] shunting the anode load produces an
advance in phase which increases the stability of the
amplifier at high frequencies.

The phase splitter, bt the way is an ECC83 - not an 82.

I must have built around a dozen of these back in the day.

Excellent performers!

However, Bob only mentioned one EL84, so perhaps he was
thinking of the Mullard 3-3:

http://www.r-type.org/articles/art-003h.htm

Outperforms anything else of a similar nature!

--

Terry

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In article ,
says...

It sounds right, with a 90V Ever ready?

Was the heater supply a separate battery? I suppose it must have been.

The Ht battery was made of pp3 type cells. Must have been 60 of them.
Damned expensive way of boiling electrons :-)


It would have been an Ever Ready B126 or equivalent, I would
guess.

Layer cells, as in a PP£ but much bigger. Rectangular, in two
stacks of 30.

Overall size: 3.75"x1.75"x2.5" (or 95mm x 45mm x 62mm)

Assuming parallel connected filaments - not heaters - a single
UR could have been used but commercial receivers used an AD35
- containing two much larger cells in parallel to give a
longer life.

Overall size: 3.125"x2.625"x1.5" (or 80mm x 67mm x 38mm)


--

Terry

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In article ,
says...

On Fri, 9 Feb 2018 10:43:29 -0000, Terry Casey
wrote:

The first TV that PYE sold claiming to be 'transistorised' had
one transistor - used as sync separator, IIRC - but everything
else remained valve driven. You might call that a sales
gimmick - and you would be right

That wasn't the abortion that was produced as a dual standard was it?

I never saw the transistor mod, but the sync was an absolute
nightmare.


I've just spent quite some time trying to find some
information on it but with no joy.

The set was a slim line 17" set and I'm sure it was 405-line
only.

The transistor wasn't a mod - it was designed that way from
new but, as we'd stopped selling PYE a few years earlier, I
never saw one working.

--

Terry

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On Fri, 09 Feb 2018 16:39:29 +0000, Archibald Tarquin Blenkinsopp wrote:

On 9 Feb 2018 16:27:21 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 15:50:07 +0000, Archibald Tarquin Blenkinsopp wrote:

On 9 Feb 2018 10:44:10 GMT, Bob Eager wrote:

On Fri, 09 Feb 2018 10:30:49 +0000, The Natural Philosopher wrote:

Yup. An OC35 on a heatsink will do about 5W class A with an output
transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very
popular in small audio kit back in the day.

The first amplifier I built *was* an EL84 class A amp, although I did
have a preamp stage too. In fact, there were two...it was stereo!

An ECC82 perchance?

A nice little double triode, albeit with a heater supply that could
trap the unwary.

No, I think they were EL84s.

The EL84 was a pentode. It was possible to use one of these as a stand
alone amp, but it was only really practical with a crystal cartridge, or
similar,

A preamp to boost the signal was often developed using an ECC82, with
one or both stages being used. The gain would still probably not be high
enough for a quality magnetic, so the lineup became Ef86 preamp, ecc82
phase splitter and two EL84s

As I said, I did have a preamp, and I think there was an ECC82 there (one
half for each channel). And probably an EF86 before it.

--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On Fri, 09 Feb 2018 16:54:51 +0000, Archibald Tarquin Blenkinsopp wrote:

I built my first radio using DF96, DAF96, DK96 and DL96 (I think).

It sounds right, with a 90V Ever ready?

90V battery, certainly.

Was the heater supply a separate battery? I suppose it must have been.

In my case it wasn't (see below). Combined in one 'box' wwere the 90V and
1.5V.

The Ht battery was made of pp3 type cells. Must have been 60 of them.
Damned expensive way of boiling electrons

I was lucky. I had (via a Royal Marine barracks and the signals
department) an almost unlimited supply of those combined batteries ...

My first wireless after the almost compulsory xtal set was a TRF with
feedback, [regenerative]. It was transistorised, and very good. I can
understand why they never were generally available to the public though.

The one I mention above was in fact a TRF. I did later build a superhet
(and wound my own IF transformers, with Litz wire - horrible stuff). It
worked OK, but not brilliantly.

--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor