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1930's/40’s radio ID please

 
FIXITNOW2003
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1930's/40’s radio ID please

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1930,s/40’s radio id please

Picked this set up at the weekend can anyone id it please
Valve on right is marked LP2 the left one is harder to read pos HL2 ??
HP2 and LP2 came out 1930 and 31 according to the Valve Museum

The white label on right hand side has written on it:

This set is designed for use with British
Valves marked BVA of the type specified
In out printed instructions issued with this receiver

So I guess it was a kit complete with case as case looks professional made.

Can anyone id it please, and a copy of the instructions would be even better.
Cheers
Vince

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Topic starter Posted : 21/12/2015 9:31 am
Jamie
(@jskinner97)
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How about this? Looks promising...
http://www.radiomuseum.org/r/eddystone_empire_two.html

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Posted : 21/12/2015 10:11 am
FIXITNOW2003
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found info for empire 2 here but looks somewhat diffrent
http://eddystoneusergroup.org.uk/Eddyst ... 20VOL1.pdf

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Topic starter Posted : 21/12/2015 10:43 am
Jamie
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Ah, just an idea...
Doesn't seem to be many sets on radio museum listed as using that valve.

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Posted : 21/12/2015 11:15 am
FIXITNOW2003
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could not find much my self will try to find time over the holidays to draw out the circuit

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Topic starter Posted : 21/12/2015 11:20 am
Cathovisor
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To be honest, it could be anything given that it's a simple two-valver. The valves may not even be original as four- and six-volt types were phased out in the early 30s - and this is more likely a late 20s/early 30s set. Chances are from the valves mentioned it'll be a typical detector-LF design, of which there were hundreds of variants but generally the design follows the usual principle of a cumulative grid detector and a triode output, usually transformer coupled. All the varying voltages will be supplied by the HT battery; typically 45v to the detector valve anode, 90 to the output valve anode.

The circuit is Boy's Own stuff.

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Posted : 21/12/2015 12:49 pm
Marconi_MPT4
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Hi,
As a starting point with the big assumption that HL2 and LP2 might just be original fit, sets listed with this line up or suggested line up are:

Marconiphone models: 22 Battery, 23 Battery and 248
GEC model: 2 Valve, B.C, 2850
Columbia model: 3S3 Batt
KB model: "Pup"
Lissen model: Colossus
Ormond model: Two-Valve
Pye model: Popular two
Red Star model: Two
"Amateur Wireless" model: Talisman 2 (1930)
"Modern Wireless" model: Star-turn 2
"Popular Wireless" models: Magic 2, Sharp-tune 2
"Wireless Constructor" model: Explorer 2

Other possibilities:
"Amateur Wireless" model: Room to Room 2 with L2/b and LP2

This by no means an exhaustive list and there is conflicting information provided by valve manufacturers.
Cheers
Rich

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Posted : 21/12/2015 6:27 pm
FIXITNOW2003
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many thanks for this will have a hunt for the circuits etc. for these cheers Vince

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Topic starter Posted : 22/12/2015 9:09 am
FIXITNOW2003
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had chance to look a bit more at this set from the list above its very much like the Marconiphone 248 /22/23 have used the 23/23a circuit

two problems the transformer is a replacement and not sure its right have done a resistance check and one winding is about 1R the other about 330R also 1 terminal has no external connection to it I guess this will need to go to grid bias neg voltage

what sort of voltage ?for grid bias

the only specs I could find for the transformer were on a circuit for the KB Masterpiece it gave 360R and 6k3

so I guess I need a suitable transformer can anyone help ??

will also need to make up a psu to give HT (not sure what voltage ) plus a 2volt heater supply and a grid voltage (not sure what voltage)
has anyone a link to a suitable supply (prefer with modern parts)
cheers Vince

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Topic starter Posted : 05/01/2016 10:40 am
Anonymous
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I built the "Battery supply for battery valve radios" a link to it and other useful projects is here.
http://www.vintage-radio.com/projects/index.html
The power supply works very well. I adapted the LT supply with a mixture of fixed and trimmer resistors and a multi-way switch so I could switch from 1.4, 2, 4, 6.3, 9, 12, 18, and 24v and use it as a general stabilised supply.

80 to 90 volt HT should be OK
For bias, the valve museum gives for the HL2 -3v and for the LP2 -4.5v but you can experiment.

Have you drawn out the circuit yet, can we see it?

Mike

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Posted : 05/01/2016 12:07 pm
FIXITNOW2003
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first circuit attempt not sure about aerial coils as not easy to buzz

not sure what speaker impedance to use

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Topic starter Posted : 05/01/2016 12:28 pm
Cathovisor
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You know the output valve is an LP2.

There are plenty of online sources that will give you data sheets for the LP2.

It's not difficult to look these up and deduce for yourself what suitable grid and anode supplies should be for it.

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Posted : 05/01/2016 12:30 pm
Anonymous
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It looks like someone has used a 50's output transformer for the intervalve one.
Is one of the LT supplies missing from the top end of the heaters?
These sets normally worked with a loudspeaker or headphones of 1000 to 2000 ohms.
If you get another intervalve transformer (not easy), then you could try the current one as an output transformer with a modern 8 ohm speaker.
Mike

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Posted : 05/01/2016 1:36 pm
FIXITNOW2003
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yes missed LT+ it goes to both pin 4's

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Topic starter Posted : 05/01/2016 1:47 pm
Terry
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The power supply works very well. I adapted the LT supply with a mixture of fixed and trimmer resistors and a multi-way switch so I could switch from 1.4 ...

Is that really 1.4V Mike?

As I'm sure you know, Michael Watterson over at UKVRRR is the expert on such matters and his opinion on the subject is:

If using an adaptor, the volts is NOT 1.5V or even 1.4V, Recommended was 1.35 +/- 10%, I'd aim for 1.33 +/- 5% for long life.
The DK96 stops first on a low battery, just under 1V.
The set should work perfectly on 1.25V

More in this thread:  http://www.forum.radios-tv.co.uk/viewtopic.php?f=3&t=10912&p=115962#p114175  and many more.

I note you don't have a nominal 7.5V setting for series connected 1.4V valves but this should similarly be derated so your 6.3V setting should be OK for these.

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Posted : 05/01/2016 6:32 pm
Cathovisor
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OTOH, 1.33V +5% = 1.4V. Also that's not taking into account drop across battery leads, switch contacts &c. If the recommended voltage was 1.35 ±10%, then 1.4V is comfortably within spec. A cumulative resistance of 0.5Ω between the output of Mike's eliminator and the sockets of the valves with a typical 4-valve set using '96' series valves would drop 63mV, bringing us back to 1.33V.

I admire Michael's caution with dry battery valves - the early octal and side-contact ones are getting quite hard to find (and I've no idea if anyone has the ultra-rare Mazda Octal ones) - but the B7G ones aren't quite on the danger list yet: Langrex have over 3,700 DF96s in stock.

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Posted : 05/01/2016 8:13 pm
Marconi_MPT4
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what sort of voltage ?for grid bias

Negative grid bias voltage for LP2 output valve is adjusted in accordance with standard battery HT voltage settings as shown in the following table. Make sure that when making GB voltage adjustments you must first disconnect HT battery otherwise the valve will be damaged if powered.

Rich

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Posted : 06/01/2016 1:10 am
FIXITNOW2003
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what sort of voltage ?for grid bias

Negative grid bias voltage for LP2 output valve is adjusted in accordance with standard battery HT voltage settings as shown in the following table. Make sure that when making GB voltage adjustments you must first disconnect HT battery otherwise the valve will be damaged if powered.

Rich

cheers Rich I will use a lm317 and 337 to make a 2v heater supply and a adjustable neg for about -1.5 to -6v
I can get a ready made pcb off the auction site for about a fiver

for the intervalve transformer I may try a mains with secondary off about 40v to give me a ratio of 6 to 1

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Topic starter Posted : 06/01/2016 9:14 am