On 26/02/16 14:27, Chris Hogg wrote:
On Fri, 26 Feb 2016 14:15:26 +0000, The Natural Philosopher
wrote:

On 26/02/16 11:40, Cursitor Doom wrote:
On Fri, 26 Feb 2016 00:12:41 +0000, The Natural Philosopher wrote:

You can still buy oc71s all right

But why not use something better?

Can you name a better photo-transistor than the OC71?
;-)

OCP71?

IIRC if you carefully stripped the paint off an OC71 you had an OCP71.

Nope. inside was blue opaque gunk after the first few years


--
"What do you think about Gay Marriage?"
"I don't."
"Don't what?"
"Think about Gay Marriage."

In article , says...

Okay, thanks for the great replies. I had a Ladybird book that showed
how to make them. Beautiful illustrations that I still look at fondly.
The first version was without batteries, and then it evolved into
something amplified with an OC71. It said to drive a long copper tube
into the ground for the earth side, but I just used a mains plug. And
the aerial was supposed to be something like a washing line, but I used
a bit of wire dangled across the room; and once, an old mattress in the
loft (which was no better). That may have reduced what I was able to
pick up :-)

Currently there is a discussion going on here which might be of interest:

http://golbornevintageradio.co.uk/fo...d.php?tid=5379

If you were to build one nowadays, would there be
any suitable non-digital station left to pick up?

There's an impressive list of stations received in Kilmarnock in post #14.

--

Terry

"Dave Plowman (News)" wrote in message
...
In article ,
The Natural Philosopher wrote:
Rubbish! we're going to cut the mooring ropes and row the islands
across the Atlantic.

And park it somewhere in the Caribbean, as a tax haven.

Surrounded by blacks? Have you run this by your kipper pals?

His kipper pals' ancestors are the reason the Caribbean is full of blacks.

In article ,
says...

[quoted text muted]

OCP71?

IIRC if you carefully stripped the paint off an OC71 you had an OCP71.

Nope. inside was blue opaque gunk after the first few years

In other words after Mullard found that they weren't selling many
OCP71's and realised what everyone was doing.

That was what most people believed at the time but there was another reason:

If the paint on a transistor got accidentally scratched and artificial light
fell on it - though a ventilation grille, for example - the transistor would
respond to the 50Hz light.

I would imagine that the first engineer to have a battery operated transistor
radio turn up on his work bench with a mains hum fault was very, very,
surprised!

Especially when he took the back off and the fault got worse ...!

So, Mullard started adding the opaque gunk ...

--

Terry

On 26/02/2016 19:16, Terry Casey wrote:
In article ,
says...

[quoted text muted]

OCP71?

IIRC if you carefully stripped the paint off an OC71 you had an OCP71.

Nope. inside was blue opaque gunk after the first few years

In other words after Mullard found that they weren't selling many
OCP71's and realised what everyone was doing.

That was what most people believed at the time but there was another reason:

If the paint on a transistor got accidentally scratched and artificial light
fell on it - though a ventilation grille, for example - the transistor would
respond to the 50Hz light.

I would imagine that the first engineer to have a battery operated transistor
radio turn up on his work bench with a mains hum fault was very, very,
surprised!

Especially when he took the back off and the fault got worse ...!

So, Mullard started adding the opaque gunk ...


When I was young, I worked for the Beeb as a technician. One day, I had
an outside broadcast mixer to check out.

While I was 'lining it up' - checking signal levels at various points -
I noticed a really bad mains hum. So I unleashed the oscilloscope. The
hum was definitely there audibly, but seemed to disappear whenever I
connected the scope probe.

To cut a very long story short, whenever I leaned over to connect a
scope probe, I put the PCB in the shadow of a fluorescent lamp and the
mains noise went away.

The mixer was all Germanium transistors. Of course, in normal use, with
the cover on, there was no problem, but when the cover was off, small
scratches in the black paint on the transistors was enough to make it
pick up the fluorescent lights, and hum.

It took a long time to find that. Nowadays, I'd just assume I'd gone
totally fishkettle aardvark alumni.

Cheers
--
Syd

On Fri, 26 Feb 2016 17:05:21 +0000, Chris Hogg wrote:

On Fri, 26 Feb 2016 16:46:56 -0000, Terry Casey
wrote:

More years ago than I care to remember I heard a report on the radio
about a woman living close to the Droitwich transmitter who could
receive the Light Programme (in the days when it was on Long Wave) on
her electric cooker ...

Drainpipes were also said to receive broadcasts. A nice long conductor
acting as an aerial probably naturally tuned by virtue of its length, a
rusty bolt acting as a semiconducting rectifier, and the pipe resonating
to create the sound.

Some people living in Kingstanding E. Sussex were able to pick up the
World Service whenever their fillings became loose.

On Fri, 26 Feb 2016 16:46:56 -0000, Terry Casey
wrote:

In article , says...


I did wonder if nearby you could receive the long wave transmissions -
198kHz @ 500kW - with just wire, a diode and a loudspeaker.


More years ago than I care to remember I heard a report on the radio about a
woman living close to the Droitwich transmitter who could receive the Light
Programme (in the days when it was on Long Wave) on her electric cooker ...

In the version I heard, I think it was a gas cooker.


--

Graham.

%Profound_observation%

On Fri, 26 Feb 2016 20:37:08 +0000, Syd Rumpo
wrote:

On 26/02/2016 19:16, Terry Casey wrote:
In article ,
says...

[quoted text muted]

OCP71?

IIRC if you carefully stripped the paint off an OC71 you had an OCP71.

Nope. inside was blue opaque gunk after the first few years

In other words after Mullard found that they weren't selling many
OCP71's and realised what everyone was doing.

That was what most people believed at the time but there was another reason:

If the paint on a transistor got accidentally scratched and artificial light
fell on it - though a ventilation grille, for example - the transistor would
respond to the 50Hz light.

I would imagine that the first engineer to have a battery operated transistor
radio turn up on his work bench with a mains hum fault was very, very,
surprised!

Especially when he took the back off and the fault got worse ...!

So, Mullard started adding the opaque gunk ...


When I was young, I worked for the Beeb as a technician. One day, I had
an outside broadcast mixer to check out.

While I was 'lining it up' - checking signal levels at various points -
I noticed a really bad mains hum. So I unleashed the oscilloscope. The
hum was definitely there audibly, but seemed to disappear whenever I
connected the scope probe.

To cut a very long story short, whenever I leaned over to connect a
scope probe, I put the PCB in the shadow of a fluorescent lamp and the
mains noise went away.

The mixer was all Germanium transistors. Of course, in normal use, with
the cover on, there was no problem, but when the cover was off, small
scratches in the black paint on the transistors was enough to make it
pick up the fluorescent lights, and hum.

It took a long time to find that. Nowadays, I'd just assume I'd gone
totally fishkettle aardvark alumni.

Cheers

There are some Raspberry Pi boards that crash if you photograph them
with a xenon flash.

When my daughter was little we bought her a VHS tape of cartoons. The
top-loading Hitachi machine we had would not play this tape. Later we
discovered it would play if the curtains were drawn. The cassette body
was made of a translucent coloured plastic instead of the usual opaque
black, allowing light to reach the optical tape end sensor that
detected the transparent leaders.


--

Graham.

%Profound_observation%

Andrew Gabriel wrote:
In article ,
"Dan S. MacAbre" writes:
Apologies to those who know about this stuff, if this is a stupid
question. Seeing the electronics thread reminded me of some of my
mis-spent youth. I never knew enough about electronics to design
anything, but I could usually get something like an amp or a tape
recorder from the tip, and fix it. That was about my limit. I used to
enjoy making crystal radios from some of the bits I'd have lying around,
but no matter what I used, I only ever seemed to be able to pick up what
seemed to be radio 4. If you were to build one nowadays, would there be
any suitable non-digital station left to pick up?

Funny you should mention this...
A couple of weeks ago, I stayed over at my parents, and in the bookshelf
was my old Ladybird book on making a radio, which takes you through the
stages of making the receiver and then adding an amplifier to it.
If you can still buy OC71's, it would still work today. ;-)

http://www.mds975.co.uk/Content/geor...trf_radio.html


Just been having another read of it this morning. Why do they not make
books like this any more? I've a six-year old boy, and we try to find
interesting educational books for him, but there's nothing now that
pulls you in like those beautiful Ladybird illustrations.

I wonder how many people tried the spring of wire and piece of coke
thing? I never did.

In article ,
pamela wrote:
I've never had a crystal set where a station is spread over an
excessively wide part of the dial. My crystal sets picked up MW
stations quite well (or as well as a crystal set can be expected).
Radio 3 used to be on 464m and it came storming in nicely even on
the crummiest tuning coil but didn't spread itself across the
band. Admittedly, those stations at the shorter wavelength end of
the band didn't come through so well.

When I was at school in Aberdeen in the '50s, schools broadcasts were
recorded on a Ferrograph using a Truvox radio jack - basically a crystal
set. It had two preset frequencies selected by a switch. Now in Aberdeen
in those days all you'd get during daylight was the local BBC
transmissions. Home Light and Third. And you could just hear another
burbling away under the wanted one on this Truvox device.

--
*Xerox and Wurlitzer will merge to market reproductive organs.

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

In article ,
Dan S. MacAbre wrote:
Just been having another read of it this morning. Why do they not make
books like this any more? I've a six-year old boy, and we try to find
interesting educational books for him, but there's nothing now that
pulls you in like those beautiful Ladybird illustrations.

I wonder how many people tried the spring of wire and piece of coke
thing? I never did.

Snag is kids see others playing with phones and computers. So that's what
interests them.

In the Ladybird days, radio might well have been the state of the art
technology.

--
*Reality is a crutch for people who can't handle drugs.

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

In message , pamela
writes
On 16:56 26 Feb 2016, Johnny B Good wrote:

On Fri, 26 Feb 2016 11:52:33 +0000, pamela wrote:

On 02:08 26 Feb 2016, Johnny B Good wrote:

On Thu, 25 Feb 2016 16:14:31 +0000, pamela wrote:

On 15:03 25 Feb 2016, Graham. wrote:

====snip====

It would if you didn't LPF it first, which would be
essential.

No, you are going to have to

LPF?

Low Pass Filter. In this case, the placement of a smoothing
capacitor of a few tens of microfarads (as opposed to a few
nanoFarads usually used to block only the rf ripple after the
detector diode) - (modern stand-in for the original lead
galena crystal and cat's whisker used to build the very first
crystal sets) so that it smooths not only the rf ripple but
the audio frequency modulation as well - you're only
interested in harvesting a few milliwatts at best (unless you
live right next door to the Tx in question) of DC voltage
produced by the detector diode that's rectifying a
conveniently strong signal to power a simple transistor
amplified radio receiver tuned to a wanted but weaker radio
station.

If you're lucky enough to pick up a very strong 198Khz signal
to power a MW transistor receiver, it's job done. However, if
you're relying on a very strong MW signal to power your MW
receiver, you'll have to get a bit more inventive and use a
second detector diode wired to give opposite polarity with the
usual rf ripple capacitor to allow the modulation to get
through, via a HPF, unmolested via a variable attenuator to
the detector of the transistor assisted reciever so as to
null out the unwanted audio that would otherwise swamp the
weaker signals you're trying to listen to. I have to admit
though, this isn't something I've ever tried. It's purely
theoretical on my part

(and it's just possible there might be a flaw in this
excellent theory of mine :-).

Why would a MW "power" station have to be treated differently
to 198lHz in the way you describe in your second paragraph
(which I can't say I fully understand)?

Lack of selectivity in the MW tuning filter. A suitably strong
enough MW broadcast is likely to be heard "Right across the
dial".


I've never had a crystal set where a station is spread over an
excessively wide part of the dial. My crystal sets picked up MW
stations quite well (or as well as a crystal set can be expected).
Radio 3 used to be on 464m and it came storming in nicely even on
the crummiest tuning coil but didn't spread itself across the
band. Admittedly, those stations at the shorter wavelength end of
the band didn't come through so well.

I'm not sure how your, albeit tentative, design (which you point
out may be somewhat flawed) would help with poor selectivity.
Wouldn't the most effective thing be an improvement to the "power
host" tuning circuit rather than the second diode arrangement you
mention?

To be honest, I can't really visualise your suggested circuit but
that may be because I don't really understand all the necessary
considerations when designing a circuit. Maybe you're trying to
overcome the problem of such a parasitic design providing power
only momentarily (when the radio signal is carrying loud audio).

The selectivity of a crystal set is greatly affected by how much the
aerial impedance damps the basic selectivity of the tuned circuit.

The selectivity might be sufficiently narrow if you have a short-ish
aerial (essentially a high capacitive impedance) connected right at the
top end of the coil - but being short, the signal it picks up might be
rather weak.

A longer aerial will pick up more signal, but will have a lower
impedance. It will have more capacitance (which will change the tuning
point of the tuned circuit) - and in particular, the resistive part of
the impedance will be lower, and this will damp (broaden) the
selectivity of the tuned circuit.

To help overcome the broadening of the selectivity, the coupling of the
aerial to the tuned circuit can be reduced either by connecting it to
the top end of the coil through a suitably low-value capacitor, or
(maybe better) by connecting it to a tapping point lower down the coil.
Either may reduce the signal somewhat, and it is a question of
experimentation to get the best results.

The other thing which broadens the selectivity is the damping effect of
the headphone(s). For best sensitivity and selectivity, these must be
high impedance, and again it may be desirable to move where the detector
diode connects to the coil to a tapping point lower down.

Those who are aficionados of crystal sets (I'm not one, BTW) may go much
further with circuit variations and complexity in order to optimise
their performance. For those interested, I'm sure that Google will
reveal all.
--
Ian

In article ,
pamela wrote:
I never heard of a Truvox Radio Jack until you mentioned it but it
looks lovely. http://www.g1jbg.co.uk/dom1.htm

That's the one. I was hoping it was an Ebay ad showing they were now worth
thousands. As I've got one somewhere. ;-)

It reminds me of a crystal set a friend showed me when I was
young. From memory, they had essentially wound a coil around what
I think was a capacitor and attached a crystal earpiece. There
was a long wire aerial feeding it.

I still can't understand how that could work as a crystal set but
maybe the crystal earpiece was somehow acting as a diode detector.

By some total fluke, this contraption actually received Radio 3.
(Which I should really be calling the Third Programme).

The whole device was smaller than that little Truvox Radio Jack.

There's not much inside them. Just a large enough case to make handling
easy - and made from metal. These days you could probably make a plastic
one much smaller but strong enough.

--
*I don't suffer from insanity -- I'm a carrier

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

On Thu, 25 Feb 2016 12:02:29 +0000, "Dan S. MacAbre"
wrote:

Dan S. MacAbre wrote:
Apologies to those who know about this stuff, if this is a stupid
question. Seeing the electronics thread reminded me of some of my
mis-spent youth. I never knew enough about electronics to design
anything, but I could usually get something like an amp or a tape
recorder from the tip, and fix it. That was about my limit. I used to
enjoy making crystal radios from some of the bits I'd have lying around,
but no matter what I used, I only ever seemed to be able to pick up what
seemed to be radio 4. If you were to build one nowadays, would there be
any suitable non-digital station left to pick up?

Okay, thanks for the great replies. I had a Ladybird book that showed
how to make them. Beautiful illustrations that I still look at fondly.
The first version was without batteries, and then it evolved into
something amplified with an OC71. It said to drive a long copper tube
into the ground for the earth side, but I just used a mains plug. And
the aerial was supposed to be something like a washing line, but I used
a bit of wire dangled across the room; and once, an old mattress in the
loft (which was no better). That may have reduced what I was able to
pick up :-)

The BBC transmitted at least one experimental broadcast of stereo,
using the Home Service and Third Programme for the left and right
channels. According to the BBC Genome website it might have been in
1958. I built two crystal sets in series, using germanium diodes,
feeding my left and right high-impedance ex-WD headphones. The aerial
was strung across the room in south London.

One item was of a theatre musical chorus, which sounded truly
wonderful.
--
Dave W

In article ,
Dave W wrote:
The BBC transmitted at least one experimental broadcast of stereo,
using the Home Service and Third Programme for the left and right
channels. According to the BBC Genome website it might have been in
1958. I built two crystal sets in series, using germanium diodes,
feeding my left and right high-impedance ex-WD headphones. The aerial
was strung across the room in south London.

Don't remember that. Those I do remember used TV sound for one channel.
IIRC on a Saturday morning when there were no broadcasts on TV - only the
test card.

To use two radio services meant disrupting them both.

One item was of a theatre musical chorus, which sounded truly
wonderful.

I did try the 'TV' ones. But with a TV and radio - with obviously very
different speakers etc. They played quite a large selection of material.

--
*Preserve wildlife - Go pickle a squirrel*

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

In article ,
Cursitor Doom wrote:
On Fri, 26 Feb 2016 09:10:38 +0000, charles wrote:

They've left the area They're now in Edgeware itself.

Tottenham Court Road used to be the mecca for electronic hobbyists back
in the day. They stocked *real* stuff back then; today it's just a load
of brand new consumer tech gadgets.

and Lisle Street before that.

--
from KT24 in Surrey, England

In article , Dave Plowman (News)
writes
In article ,
Dave W wrote:
The BBC transmitted at least one experimental broadcast of stereo,
using the Home Service and Third Programme for the left and right
channels. According to the BBC Genome website it might have been in
1958. I built two crystal sets in series, using germanium diodes,
feeding my left and right high-impedance ex-WD headphones. The aerial
was strung across the room in south London.

Don't remember that. Those I do remember used TV sound for one channel.
IIRC on a Saturday morning when there were no broadcasts on TV - only the
test card.

To use two radio services meant disrupting them both.

One item was of a theatre musical chorus, which sounded truly
wonderful.

I did try the 'TV' ones. But with a TV and radio - with obviously very
different speakers etc. They played quite a large selection of material.

I remember that! There was a broadcast of Shakespeare's 'The Tempest' -
very effective sound effects.
--
Chris Holford

In article , Chris Hogg
wrote:
On Sun, 28 Feb 2016 08:13:18 +0000, Chris Hogg wrote:

On Sat, 27 Feb 2016 20:03:38 +0000 (GMT), charles
wrote:

In article , Cursitor Doom
wrote:
On Fri, 26 Feb 2016 09:10:38 +0000, charles wrote:

They've left the area They're now in Edgeware itself.

Tottenham Court Road used to be the mecca for electronic hobbyists
back in the day. They stocked *real* stuff back then; today it's
just a load of brand new consumer tech gadgets.

and Lisle Street before that.

http://tinyurl.com/gn69z3a

3-34 Lisle Street! They occupied almost the entire length of it, IIRC.

Actually, memory deceives, it was two separate shops!

There were some at each end of the street as well as one in the middle on
the north side. And then the chinese took over.

--
from KT24 in Surrey, England

On Sat, 27 Feb 2016 17:54:07 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Dave W wrote:
The BBC transmitted at least one experimental broadcast of stereo,
using the Home Service and Third Programme for the left and right
channels. According to the BBC Genome website it might have been in
1958. I built two crystal sets in series, using germanium diodes,
feeding my left and right high-impedance ex-WD headphones. The aerial
was strung across the room in south London.

Don't remember that. Those I do remember used TV sound for one channel.
IIRC on a Saturday morning when there were no broadcasts on TV - only the
test card.

To use two radio services meant disrupting them both.

One item was of a theatre musical chorus, which sounded truly
wonderful.

I did try the 'TV' ones. But with a TV and radio - with obviously very
different speakers etc. They played quite a large selection of material.

The radio+TV broadcasts were in 1962, and I didn't have a TV.
--
Dave W

In article ,
Dave W wrote:
On Sat, 27 Feb 2016 17:54:07 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Dave W wrote:
The BBC transmitted at least one experimental broadcast of stereo,
using the Home Service and Third Programme for the left and right
channels. According to the BBC Genome website it might have been in
1958. I built two crystal sets in series, using germanium diodes,
feeding my left and right high-impedance ex-WD headphones. The aerial
was strung across the room in south London.

Don't remember that. Those I do remember used TV sound for one channel.
IIRC on a Saturday morning when there were no broadcasts on TV - only the
test card.

To use two radio services meant disrupting them both.

One item was of a theatre musical chorus, which sounded truly
wonderful.

I did try the 'TV' ones. But with a TV and radio - with obviously very
different speakers etc. They played quite a large selection of material.

The radio+TV broadcasts were in 1962, and I didn't have a TV.

nor did I, but the FM tuner that I'd built to a PW design could tune down
to Band 1 if I inserted an iron dust slug in one of the coils. It can't
have been a very good tuner since it managed the AM on Band 1.

--
from KT24 in Surrey, England

On Sun, 28 Feb 2016 11:21:42 +0000 (GMT), charles
wrote:

In article ,
Dave W wrote:
On Sat, 27 Feb 2016 17:54:07 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Dave W wrote:
The BBC transmitted at least one experimental broadcast of stereo,
using the Home Service and Third Programme for the left and right
channels. According to the BBC Genome website it might have been in
1958. I built two crystal sets in series, using germanium diodes,
feeding my left and right high-impedance ex-WD headphones. The aerial
was strung across the room in south London.

Don't remember that. Those I do remember used TV sound for one channel.
IIRC on a Saturday morning when there were no broadcasts on TV - only the
test card.

To use two radio services meant disrupting them both.

One item was of a theatre musical chorus, which sounded truly
wonderful.

I did try the 'TV' ones. But with a TV and radio - with obviously very
different speakers etc. They played quite a large selection of material.

The radio+TV broadcasts were in 1962, and I didn't have a TV.

nor did I, but the FM tuner that I'd built to a PW design could tune down
to Band 1 if I inserted an iron dust slug in one of the coils. It can't
have been a very good tuner since it managed the AM on Band 1.

I too built an FM tuner that could get TV sound - it might have been
the same one as yours as PW was my regular buy. However the sound from
the speaker was so different from the radio headphones, I didn't think
it would be worth trying the stereo experiments. I was so impressed
with the radio experiment that it was just a question of waiting for
proper stereo broadcasts.
--
Dave W

In article , Chris Hogg
scribeth thus
On Sat, 27 Feb 2016 20:03:38 +0000 (GMT), charles
wrote:

In article ,
Cursitor Doom wrote:
On Fri, 26 Feb 2016 09:10:38 +0000, charles wrote:

They've left the area They're now in Edgeware itself.

Tottenham Court Road used to be the mecca for electronic hobbyists back
in the day. They stocked *real* stuff back then; today it's just a load
of brand new consumer tech gadgets.

and Lisle Street before that.

http://tinyurl.com/gn69z3a

3-34 Lisle Street! They occupied almost the entire length of it, IIRC.


Did you have to publish that!. Spent all afternoon reading it all
through!.

Remember most all of those suppliers, a teenage childhood of sending off
postal orders and stamped addressed envelopes, and the excitement when
the package for the latest project turned up:!.
--
Tony Sayer

To use two radio services meant disrupting them both.
terial.

The radio+TV broadcasts were in 1962, and I didn't have a TV.



nor did I, but the FM tuner that I'd built to a PW design could tune down
to Band 1 if I inserted an iron dust slug in one of the coils. It can't
have been a very good tuner since it managed the AM on Band 1.


Charles, do you remember which one that was at all, valve or
transistor?.

I remember one i think it had a pulse count detector used IIRC AF117's
and or 118's in the front end and was supposed to be a very good
performer, never did get the damm thing to work checked it and re
checked tested all the transistors. I wish i had it around still, years
on better test equipment and know how etc?.

Often wondered if it could have worked!, anyone know where the circuit
is at all? must have been around 1966 to 68 or even a bit later.

--
Tony Sayer

In article ,
tony sayer wrote:
To use two radio services meant disrupting them both.
terial.

The radio+TV broadcasts were in 1962, and I didn't have a TV.



nor did I, but the FM tuner that I'd built to a PW design could tune down
to Band 1 if I inserted an iron dust slug in one of the coils. It can't
have been a very good tuner since it managed the AM on Band 1.


Charles, do you remember which one that was at all, valve or
transistor?.

Valve. Using an ex-government IF strip.

[Snip]

Often wondered if it could have worked!, anyone know where the circuit
is at all? must have been around 1966 to 68 or even a bit later.

Mine must have been about 1958/9.

--
from KT24 in Surrey, England

In article , charles
scribeth thus
In article ,
tony sayer wrote:
To use two radio services meant disrupting them both.
terial.

The radio+TV broadcasts were in 1962, and I didn't have a TV.



nor did I, but the FM tuner that I'd built to a PW design could tune down
to Band 1 if I inserted an iron dust slug in one of the coils. It can't
have been a very good tuner since it managed the AM on Band 1.


Charles, do you remember which one that was at all, valve or
transistor?.

Valve. Using an ex-government IF strip.

[Snip]

Often wondered if it could have worked!, anyone know where the circuit
is at all? must have been around 1966 to 68 or even a bit later.

Mine must have been about 1958/9.


Ah!, a very early FM tuner then. That government surplus IF strip what
was it originally for surely not FM broadcast radio?.
--
Tony Sayer

In article , tony sayer
wrote:
In article , charles
scribeth thus
In article , tony sayer
wrote:
To use two radio services meant disrupting them both.
terial.

The radio+TV broadcasts were in 1962, and I didn't have a TV.



nor did I, but the FM tuner that I'd built to a PW design could tune
down to Band 1 if I inserted an iron dust slug in one of the coils.
It can't have been a very good tuner since it managed the AM on Band
1.


Charles, do you remember which one that was at all, valve or
transistor?.

Valve. Using an ex-government IF strip.

[Snip]

Often wondered if it could have worked!, anyone know where the
circuit is at all? must have been around 1966 to 68 or even a bit
later.

Mine must have been about 1958/9.


Ah!, a very early FM tuner then. That government surplus IF strip what
was it originally for surely not FM broadcast radio?.

Of course not. I think it came from a Radar unit.

--
from KT24 in Surrey, England