On Fri, 09 Feb 2018 18:56:16 +0000, Terry Casey wrote:

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.

Uncle Albert Mode
During the war /Uncle Albert Mode my mum and I lived in Hampshire with
an aunt and my cousins and she had a 'wireless' which needed an HT
battery, a grid bias battery and an accumulator for the filaments. The
latter had to be taken to the local bike shop to be recharged and IIRC
they actually exchanged the discharged one for a freshly charged one.

--
TOJ.

On Friday, 9 February 2018 16:39:40 UTC, Archibald Tarquin Blenkinsopp wrote:

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

reduce gain at high frequency


NT

On Friday, 9 February 2018 16:55:03 UTC, Archibald Tarquin Blenkinsopp wrote:

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

they were the main type offered to the public in the 19 teens, 20s & early 30s. They also hung on at the cheap end of the market in the 40s.


NT

On Friday, 9 February 2018 18:12:05 UTC, Max Demian wrote:
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.

the cap sections needed to not quite track because they were in different bits of circuit with differing chracteristics. That's where the problem was. Later that was all figured out & the extra bits became affordable.


NT

On Fri, 09 Feb 2018 17:08:49 +0000, Dave Plowman (News) wrote:

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.

It would have a characteristic impedance, presumably a lot higher than
the more typical 50/75/93 ohm impedance figures typical of proper co-ax
feeder cable. I'm not sure whether it could have been as high as 300 ohms
which would be a side effect of trying to keep the shunt capacitance per
metre figure as low as possible since it was being used not as a
conventional co-axial feeder working into a matched load but simply as a
screened section of the antenna designed to eliminate electrical noise
within the interior of the vehicle from interfering with the radio signal
picked up by the external portion of the antenna mounted outside of the
Faraday shielding of the vehicle cab.


IIRC, more modern radios match to the aerial automatically.

The early MW/LW car radios used valves which, when used in common
cathode mode, provided a high impedance input which could be connected
across the first stage tuning circuit for maximum sensitivity without
compromising the Q of the tuned circuit.

It was standard practice to use permeability tuning (variable
inductance) in order to keep the L:C ratio as high as possible to get the
maximum voltage magnifying effect out of a circuit where most of the
capacitance was supplied by that of the *shielded* antenna wire and the
short external unshielded bit that acted as an electric field probe
antenna. The combination of variable inductor/adjustable padding
capacitor/screened aerial wire section plus exposed aerial rod
capacitance, formed the first tuned section of the receiver.

There were two very good reasons to choose permeability tuning over
variable capacitor tuning, both touched upon above. Firstly, and
foremost, the need to eliminate the "pot down" effect of a tuning
capacitor and secondly, the elimination of a bulky two/three gang 300 to
500pF air spaced tuning capacitor in favour of the much more compact slug
tuned two/three variable inductor bank.

In theory, it shouldn't make any difference as to which part of the
tuning dial you found a suitably weak signal by which to trim the aerial
circuit to peak response provided the Local Oscillator (LO) tracking had
been closely matched to the RF tuned circuit(s). However, choosing a
suitable station at the HF end of the band may have helped compensate for
LO tuning tracking errors in most cost effectively manufactured designs.

Although such a small 'probe antenna' setup only brings in a tiny
fraction of the signal that a full 100 odd foot vertical quarter wave
ground plane would, the effective broadcasting range on the MW and LW
wavebands is limited by the very high noise levels from atmospheric
sources (QRN) in those wavebands. This circumstance meant that such tuned
probe antennas were entirely fit for their intended purpose in spite of
this obvious shortcoming.

--
Johnny B Good

On Thu, 08 Feb 2018 20:50:08 +0000, Huge wrote:

On 2018-02-08, Chris Bartram wrote:
On 08/02/2018 11:53, 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.

With a decent, modern, well-regulated charger, it isn't an issue. With
an old, poorly regulated, poorly rectified one I'd be more cautious.

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.

I had a look at the description in the linked page and they do seem to
be 'just the ticket'. The only concern I had was the absence of any
mention as to what the 'maintenance' voltage was. If it's 13.5v, ok but
if it's 13.8v I'd be inclined to plug it in via a cheep 'n' cheerful
electromechanical timer set to let it run for an hour or two per day
rather than chance leaving it permanently floated at 13.8v month after
month.

--
Johnny B Good

On 09/02/2018 00:54, Dave Plowman (News) wrote:
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.

I've checked a lot of batteries. I regard 11.75V as fully discharged.

Bill

On Fri, 9 Feb 2018 19:23:11 -0000, Terry Casey
wrote:

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.

I have little doubt that your memory is better than mine regarding the
model, but I would never have associated transistors with single
standard VHF sets.

Was flywheel sync in use in VHF sets?

I could look it up, but my Newnes Radio and TV servicing library went
in the bin a number of years back.

Amazing times though, it was interesting to see different
manufacturers approaches to electronics problems.

Thorns "wattless dropper" was one of the most memorable, particlarly
when the "dropper" shorted.

I have recollections of cleaning terret tuners, in particular during
the three day week when during power cuts we were issued portable gas
lamps to do repairs by [We were salaried].

Thanks to the miners our customers had VHF tuners that were absolutely
spot on, no hairbrush or comb wedged between case and tuner knob for
them. Pity they were all on UHF and couldn't appreciate it. :-(


Happy days

AB

In article 20180209180959.39c7b031@Mars,
Rob Morley wrote:
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.

Same here. Can't resist a treat when doing the 'normal' shopping. But
everything does get used - eventually.

--
*Ambition is a poor excuse for not having enough sense to be lazy *

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

In article ,
Bill Wright wrote:
On 09/02/2018 00:54, Dave Plowman (News) wrote:
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.

I've checked a lot of batteries. I regard 11.75V as fully discharged.

Ah. I have a very accurate digital voltmeter sitting across the car
battery, and it has started with a lower voltage than that.

(The voltmeter is wired directly to the battery, via a relay switched with
the ignition.)

--
*One of us is thinking about sex... OK, it's me.

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

On 09/02/18 18:41, Terry Casey wrote:
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!

With a decent transformer, probbaly better quality thanm most amps of
that power around today:-)



--
Those who want slavery should have the grace to name it by its proper
name. They must face the full meaning of that which they are advocating
or condoning; the full, exact, specific meaning of collectivism, of its
logical implications, of the principles upon which it is based, and of
the ultimate consequences to which these principles will lead. They must
face it, then decide whether this is what they want or not.

Ayn Rand.

On 09/02/18 20:47, Johnny B Good wrote:
Although such a small 'probe antenna' setup only brings in a tiny
fraction of the signal that a full 100 odd foot vertical quarter wave
ground plane would, the effective broadcasting range on the MW and LW
wavebands is limited by the very high noise levels from atmospheric
sources (QRN) in those wavebands. This circumstance meant that such tuned
probe antennas were entirely fit for their intended purpose in spite of
this obvious shortcoming.

Yup.

Boosting gain just boosted the noise as well.


--
Outside of a dog, a book is a man's best friend. Inside of a dog it's
too dark to read.

Groucho Marx

In message , "Dave Plowman (News)"
writes
In article ,
Bill Wright wrote:
On 09/02/2018 00:54, Dave Plowman (News) wrote:
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.

I've checked a lot of batteries. I regard 11.75V as fully discharged.

Ah. I have a very accurate digital voltmeter sitting across the car
battery, and it has started with a lower voltage than that.

(The voltmeter is wired directly to the battery, via a relay switched with
the ignition.)

One dark night at the beginning of January 1965, when in my 1953 Ford
Prefect, with a dead flat* 6V battery (almost zero volts), I rolled it
down a hill from Englefield Green to Runnymede (A328) - and bump started
it. At the bottom of the hill, when I switched the lights on, the
additional load on the dynamo nearly stalled the engine. Of course,
those were the days before alternators and clever electronics.
*It was dead flat because I had my amateur radio equipment installed in
the car - and I had foolishly left the valve heaters on all over the
Christmas holiday week. Fortunately, I had a spare car battery.
--
Ian

In article , Ian Jackson
wrote:
In message , "Dave Plowman (News)"
writes
In article , Bill Wright
wrote:
On 09/02/2018 00:54, Dave Plowman (News) wrote:
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.

I've checked a lot of batteries. I regard 11.75V as fully discharged.

Ah. I have a very accurate digital voltmeter sitting across the car
battery, and it has started with a lower voltage than that.

(The voltmeter is wired directly to the battery, via a relay switched
with the ignition.)

One dark night at the beginning of January 1965, when in my 1953 Ford
Prefect, with a dead flat* 6V battery (almost zero volts), I rolled it
down a hill from Englefield Green to Runnymede (A328) - and bump started
it.

Good thing you had control before you hit the river ;-)

--
from KT24 in Surrey, England

In article ,
The Natural Philosopher wrote:
On 09/02/18 18:41, Terry Casey wrote:
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!

With a decent transformer, probbaly better quality thanm most amps of
that power around today:-)

Why would anyone want such a low powered high quality power amp these days?

It was OK in the days of vast super efficient speakers.

--
*Very funny Scotty, now beam down my clothes.

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

In article ,
says...

... my mum and I lived in Hampshire with
an aunt and my cousins and she had a 'wireless' which needed an HT
battery, a grid bias battery and an accumulator for the filaments. The
latter had to be taken to the local bike shop to be recharged and IIRC
they actually exchanged the discharged one for a freshly charged one.

It was more common, I think you'll find, to buy two
accumulators so that while one was in use, the spare was at
the cycle/radio shop or garage being recharged. Whether you
always got your own accumulator back I don't know!

--

Terry

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

In article ,
says...


I have little doubt that your memory is better than mine regarding the
model, but I would never have associated transistors with single
standard VHF sets.

Was flywheel sync in use in VHF sets?


PYE introduced a fully transistorised TV quite early on in the
60s but I was quite surprised to find this:

http://www.semiconductormuseum.com/T...CA/OralHistori
es/Herzog/Herzog_Page8.htm

or https://tinyurl.com/yaakbojp

"RCA was second only to Bell Labs in the number of patents
related to transistor inventions in the early 1950s. The
above photo (from the 1953 RCA publication ?Transistors?)
shows a number of historic transistorized devices developed at
the RCA Labs and demonstrated at an RCA licensee transistor
symposium in 1952 in Princeton, NJ. Of particular note is
the first completely transistorized television receiver, shown
on the left side of the above photo ..."

This would have been a laboratory prototype rather than a
production set but Philco put a portable set on the market in
the states in 1959. I can't find a reference to the CRT size
but the cabinet was only 8" wide so no more than 6" or
possibly 7".

Sony introduced an 8" set in 1960 (again, not in the UK).

There were two UK sets introduced the following year, though.

The Transvista 743T by Ferguson was another 7" portable but it
was PYE who introduced the first 14" model - remember that in
1961, 14" sets were still very popular.

https://www.radiomuseum.org/r/pye_tt1transisto.html

Note the number of valves/tubes is stated as two - one was the
CRT but the other would have been the EHT rectifier.


The first UK set I am aware of with flywheel sync was the PYE
V4, released in 1953.

The set is usually remembered these days for the use of gated
AGC, primarily because it was heavily promoted in all PYE's
publicity as 'Automatic Picture Control'

However, a brief mention on this page:

http://www.thevalvepage.com/tv/pye/v4/v4.htm

suggests that it had been used earlier on fringe sets.

--

Terry

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

On Sat, 10 Feb 2018 12:02:20 +0000, Terry Casey wrote:

It was more common, I think you'll find, to buy two accumulators so that
while one was in use, the spare was at the cycle/radio shop or garage
being recharged. Whether you always got your own accumulator back I
don't know!

You may be right - I was only about 4 at the time and my memory ain't that
good!

--
TOJ.

In article ,
Terry Casey wrote:
In article ,
says...

... my mum and I lived in Hampshire with
an aunt and my cousins and she had a 'wireless' which needed an HT
battery, a grid bias battery and an accumulator for the filaments. The
latter had to be taken to the local bike shop to be recharged and IIRC
they actually exchanged the discharged one for a freshly charged one.

It was more common, I think you'll find, to buy two
accumulators so that while one was in use, the spare was at
the cycle/radio shop or garage being recharged. Whether you
always got your own accumulator back I don't know!

Think it would depend on the size of the place. In the rural Scottish area
an aunt lived in they re-charged your own one. I'd guess an exchange
system would cost more which would explain it.

--
*How do you tell when you run out of invisible ink? *

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

In article ,
Terry Casey wrote:
The Transvista 743T by Ferguson was another 7" portable but it
was PYE who introduced the first 14" model - remember that in
1961, 14" sets were still very popular.

They may have still been on sale, but 17" was more common for new sales,
with 21" being around too.

IIRC, colour was the real problem. With the first colour sets still having
valve LOP.

--
*No sentence fragments *

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

On Sat, 10 Feb 2018 13:40:28 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Terry Casey wrote:
The Transvista 743T by Ferguson was another 7" portable but it
was PYE who introduced the first 14" model - remember that in
1961, 14" sets were still very popular.

They may have still been on sale, but 17" was more common for new sales,
with 21" being around too.

IIRC, colour was the real problem. With the first colour sets still having
valve LOP.

Thorn 2000, can't even recollect whether it was single or dual
standard, but at every Thorn training course I went on they reminded
us of the fact, they also stated that there was one in the science
museum.

Cant remember the Pye though, I certaily would appreciate a link if
anyone knows of one. The first transistorised portable I remember was
the Thorn 1590 although there was a Rigonda TV out at around the same
time. I seem to remember the Rigonda was sold via furniture stores and
through Kelloggs. How many bowls of Frosties needed to be consumed to
get one, God knows :-)

AB

On Sat, 10 Feb 2018 11:18:40 +0000, Dave Plowman (News) wrote:

In article ,
The Natural Philosopher wrote:
On 09/02/18 18:41, Terry Casey wrote:
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!

With a decent transformer, probbaly better quality thanm most amps of
that power around today:-)

Why would anyone want such a low powered high quality power amp these
days?

It was OK in the days of vast super efficient speakers.

My speakers are 4 cu ft. bass reflexes.

--
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 10/02/18 15:06, Bob Eager wrote:
On Sat, 10 Feb 2018 11:18:40 +0000, Dave Plowman (News) wrote:

In article ,
The Natural Philosopher wrote:
On 09/02/18 18:41, Terry Casey wrote:
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!

With a decent transformer, probbaly better quality thanm most amps of
that power around today:-)

Why would anyone want such a low powered high quality power amp these
days?

It was OK in the days of vast super efficient speakers.

My speakers are 4 cu ft. bass reflexes.

3W-100W is only 15dB



--
"Women actually are capable of being far more than the feminists will
let them."

In article ,
says...

In article ,
Terry Casey wrote:
The Transvista 743T by Ferguson was another 7" portable but it
was PYE who introduced the first 14" model - remember that in
1961, 14" sets were still very popular.

They may have still been on sale, but 17" was more common for new sales,
with 21" being around too.


Yes. Funnily enough, I was just thinking this through.

I'm thinking more about the sets I was reparing in early 1961
rather than what thery were selling downstairs in the shop!

We were Bush dealers and the TV95 was introduced round about
the time I started work in Septemner 1960. The TV95 was 17" as
were most of the other sets in the range be it fringe sets or
sets with FM radio.

There was also the 21" TV99 and console models T98C and T99C
but very few 21" sets passed through my hands so the 17" sets
were obviously much more popular.

The last 14" set was the TV63 and, as Bush model numbers went
up by 10 every year, that dates it to 1957.

The 19" sets ousted the 17" ones in 1961 as the smallest
screen size generally available with the advent of the TV105.

--

Terry

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