Oldtimer question (valves/tubes)

[Cursitor Doom]

On Mon, 13 May 2019 20:46:03 +1000, Lucifer wrote:

I did have a one valve test oscillator which was powered by a nine volt
grid bias battery.

Tust the grid alone was battery powered? Seems a bit of a strange idea. I
mean, it's entirely feasible, but if you have to generate higher voltages
for the anode from the mains....





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[Lucifer]

On Sun, 12 May 2019 11:04:06 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

Gentlemen,

I've got this RF sig gen I'm testing at the moment. It was made in 1955
and is all valve (I say "all valve" but there are only two tubes in it
and only one of those generates the RF - the other's 400Hz for the
modulation).
Anyway, it has 8 ranges in total covering 100KHz to 240Mhz. The
oscillator tube is a double triode, a 12AT7. One half handles range from
100Khz to 30Mhz and the other takes care of 30 - 240Mhz. Now, it all
works great EXCEPT for one range (the 3rd lowest) which has appreciable
distortion present on the output. It looks a bit like it's being over-
driven on my scope. My question is, does a valve like a 12AT7 require
different DC biasing points for every range of frequencies? Obviously the
range switch is switching in different combinations of coils and
capacitors, but is it likely to be also switching in different cathode-
grid DC biasing at the same time?

I have a Radiosonde weather balloon transmitter which has a
single valve. The valve is a 3A5 twin triode with one being the
RF oscillator at 72 MHz and the other an audio oscillator which
was controlled by the sensors.

I did have a one valve test oscillator which was powered by
a nine volt grid bias battery.



>TIA

 

[Lucifer]

On Sun, 12 May 2019 15:53:17 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Sun, 12 May 2019 08:46:42 -0700, tabbypurr wrote:

If you've eliminated other faults as possible then time to adjust the
bias on the iffy range.

It breaks my heart to do this, but I think it's a junker. On further
inspection some screwdriver jockey's fucked around with it and since I
only paid a fiver for it, it's time to consign it to recycling.

I picked up a valve paging transmitter from a rubbish tip.
It was in working order, 5 watts output on 27.212 MHz,
with the crystal in an oven.

 

[Cursitor Doom]

On Mon, 13 May 2019 20:53:55 +1000, Lucifer wrote:

I picked up a valve paging transmitter from a rubbish tip.
It was in working order, 5 watts output on 27.212 MHz, with the crystal
in an oven.

Nice find. It's amazing what gets thrown out! I dream of owning an
apartment overlooking a vast garbage tip so I can spot anything
potentially valuable being dumped. ;-)





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[Lucifer]

On Mon, 13 May 2019 11:23:51 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Mon, 13 May 2019 20:53:55 +1000, Lucifer wrote:

I picked up a valve paging transmitter from a rubbish tip.
It was in working order, 5 watts output on 27.212 MHz, with the crystal
in an oven.

Nice find. It's amazing what gets thrown out! I dream of owning an
apartment overlooking a vast garbage tip so I can spot anything
potentially valuable being dumped. ;-)

I have found so many amazing things at tips.
A bag of stained glass hobby bits and pieces.
Photo copiers I spent hours dismantling.

Auctions are a good cheap source of what many people call junk.

 

[Lucifer]

On Mon, 13 May 2019 11:31:05 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Mon, 13 May 2019 20:46:03 +1000, Lucifer wrote:

I did have a one valve test oscillator which was powered by a nine volt
grid bias battery.

Tust the grid alone was battery powered? Seems a bit of a strange idea. I
mean, it's entirely feasible, but if you have to generate higher voltages
for the anode from the mains....

The nine volts was the anode voltage!
I had a hybrid car radio with 4 valves and 2 transistors.
The valves used the 12 volts for the anode voltage.

Valves don't need high voltage on the anode for low power
applications.

 

[Fox's Mercantile]

On 5/13/19 6:46 AM, Lucifer wrote:

On Mon, 13 May 2019 11:31:05 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Mon, 13 May 2019 20:46:03 +1000, Lucifer wrote:

I did have a one valve test oscillator which was powered by a nine volt
grid bias battery.

Tust the grid alone was battery powered? Seems a bit of a strange idea. I
mean, it's entirely feasible, but if you have to generate higher voltages
for the anode from the mains....

The nine volts was the anode voltage!
I had a hybrid car radio with 4 valves and 2 transistors.
The valves used the 12 volts for the anode voltage.

Valves don't need high voltage on the anode for low power
applications.

<http://www.junkbox.com/electronics/lowvoltagetubes.shtml>

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

[Cursitor Doom]

On Mon, 13 May 2019 21:52:09 +1000, Lucifer wrote:

I have found so many amazing things at tips.
A bag of stained glass hobby bits and pieces.
Photo copiers I spent hours dismantling.

Auctions are a good cheap source of what many people call junk.

What's worth salvaging from old photocopiers? I vaguely recall there's
some exotic goodies in them somewhere.





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[Cursitor Doom]

On Mon, 13 May 2019 21:46:56 +1000, Lucifer wrote:

The nine volts was the anode voltage!
I had a hybrid car radio with 4 valves and 2 transistors.
The valves used the 12 volts for the anode voltage.

Valves don't need high voltage on the anode for low power applications.

I'll have to look into that. I had no idea of such extraordinarily low
plate voltages as that. 9V eh? Wow! Do you happen to remember the type
number of those? I'd be fascinated to check out the data sheet for 'em.





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[Wond]

On Mon, 13 May 2019 14:23:35 +0000, Cursitor Doom wrote:

On Mon, 13 May 2019 21:52:09 +1000, Lucifer wrote:

I have found so many amazing things at tips. A bag of stained glass
hobby bits and pieces. Photo copiers I spent hours dismantling.

Auctions are a good cheap source of what many people call junk.

What's worth salvaging from old photocopiers? I vaguely recall there's
some exotic goodies in them somewhere.

In a good copier, there's an excellent lens, for a start.

 

[Ralph Mowery]

In article <qbbusf$p45$2@dont-email.me>, curd@notformail.com says...

I'll have to look into that. I had no idea of such extraordinarily low
plate voltages as that. 9V eh? Wow! Do you happen to remember the type
number of those? I'd be fascinated to check out the data sheet for 'em.

At one time the car radios had low voltage tubes in them that just ran
on 12 volts . They could not supply the power for the audio output, so
a transisitor or two were used in the audio stages. Tubes worked well
for the radio frequency signals and transistors not so well in those
years.

Back in the eairly 1960's I built a one tube receiver for the airplanes
that ran on 12 volts only. Plans were in a Popular Electronics of the
same years. Had to use earphones for it.

 

[Cursitor Doom]

On Mon, 13 May 2019 10:57:54 -0400, Ralph Mowery wrote:

Back in the eairly 1960's I built a one tube receiver for the airplanes
that ran on 12 volts only. Plans were in a Popular Electronics of the
same years. Had to use earphones for it.

Those awful high impedance ones, by any chance?





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[Cursitor Doom]

On Mon, 13 May 2019 09:39:11 -0500, Fox's Mercantile wrote:

> <http://www.junkbox.com/electronics/lowvoltagetubes.shtml>

Thanks!

 

[Ralph Mowery]

In article <qbc3mj$p45$3@dont-email.me>, curd@notformail.com says...

Back in the eairly 1960's I built a one tube receiver for the airplanes
that ran on 12 volts only. Plans were in a Popular Electronics of the
same years. Had to use earphones for it.

Those awful high impedance ones, by any chance?

Some of the older ones that were around 1000 ohms or more impedance
phones. The lower ones would not work.

 

[Mike Coon]

In article <MPG.374358d8d2aa025d5b@news.plus.net>,
gravity@mjcoon.plus.com says...

In article <qba4km$gun$9@dont-email.me>, curd@notformail.com says...

On Sun, 12 May 2019 22:00:16 +0100, Mike Coon wrote:

Highly unlikely. I still have Dad's "Universal Avometer Model 7", so if
the valve tester was from the same stable I would have linked the two.
Unfortunately I can't find any record of my offer to Bletchley, to a
chap who IIRC has since died.

I think you'll find AVO took over Taylor in the late 1950s so it's all
just about dates of manufacture.

Oh, thanks, I might look that up. But the valve tester would certainly
be older than that. It did have a lacquered wooden case, after all!

Mike.

See https://www.radiomuseum.org/r/taylor_valve_tester_47a47.html

Mike.

 

[Cursitor Doom]

On Mon, 13 May 2019 18:14:29 +0100, Mike Coon wrote:

> See https://www.radiomuseum.org/r/taylor_valve_tester_47a47.html

Very nice, that. You should hang on to it; valves seem to be making a
comeback in some areas.





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[Clifford Heath]

On 14/5/19 12:23 am, Cursitor Doom wrote:

On Mon, 13 May 2019 21:52:09 +1000, Lucifer wrote:
What's worth salvaging from old photocopiers? I vaguely recall there's
some exotic goodies in them somewhere.

Perhaps not exotic, but they tend to have a few nice 24V motors.

 

[Lucifer]

On Mon, 13 May 2019 14:27:27 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Mon, 13 May 2019 21:46:56 +1000, Lucifer wrote:

The nine volts was the anode voltage!
I had a hybrid car radio with 4 valves and 2 transistors.
The valves used the 12 volts for the anode voltage.

Valves don't need high voltage on the anode for low power applications.

I'll have to look into that. I had no idea of such extraordinarily low
plate voltages as that. 9V eh? Wow! Do you happen to remember the type
number of those? I'd be fascinated to check out the data sheet for 'em.

I don't remember other that the car radio used transistors for the
second audio and the audio output and valves for the rest.

 

[Lucifer]

On Mon, 13 May 2019 09:39:11 -0500, Fox's Mercantile <jdangus@att.net>
wrote:

On 13/05/19 6:46 AM, Lucifer wrote:
On Mon, 13 May 2019 11:31:05 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Mon, 13 May 2019 20:46:03 +1000, Lucifer wrote:

I did have a one valve test oscillator which was powered by a nine volt
grid bias battery.

Tust the grid alone was battery powered? Seems a bit of a strange idea. I
mean, it's entirely feasible, but if you have to generate higher voltages
for the anode from the mains....

The nine volts was the anode voltage!
I had a hybrid car radio with 4 valves and 2 transistors.
The valves used the 12 volts for the anode voltage.

Valves don't need high voltage on the anode for low power
applications.


http://www.junkbox.com/electronics/lowvoltagetubes.shtml

Very interesting. Thank you.

 

[Mike Coon]

In article <qbcafc$6ea$1@dont-email.me>, curd@notformail.com says...

On Mon, 13 May 2019 18:14:29 +0100, Mike Coon wrote:

See https://www.radiomuseum.org/r/taylor_valve_tester_47a47.html

Very nice, that. You should hang on to it; valves seem to be making a
comeback in some areas.

Too late; assuming they have not thrown it away, it has been at
Bletchley Park for several years, hopefully supporting their old
computer resusitation projects.

Mike.