Hi there

I am trying to find information on a battery set that I have picked up.
It is an STC 511 "D". I have looked at the AORMS lists and it is not listed.

Does anyone out there have any info on this set. I am after the Voltage for the A and B supply, Frequency of the IF and any other relevant information that people might have.

I have tried looking through the net but I can't find anything that looks like it. The only thing I found was a STC 511 witch is a mains powered set.

My valve line up (Well according to the Layout sticker!) is as follows:

1P5G, 1A7G, 1P5G, 1H5G, 1Q5G
(I cant read the valve types at the moment as I haven't stripped it down yet.)

It was probably made around 1941.
The Chassis was/is type 511

The type 510 batt set is NOT the same!

Thanks

Daniel.

Hello Daniel

Can you read the ARTS&P prefix letter? This will set the year of manufacture.

550P and 258G have the same line-up
http://www.hws.org.au/RadioHistory/manufacturers/STC.htm

Graham

Http://www.thebakeliteradio.com/Circuits/STC/

Try the above, but agree that pattern does not fit the cloth.
I would before speculating, look at the valves and see what they are.

The numbers on those valves mentioned tell me they are octals and may actually be pre 1940 as thats when the minatures started to appear.

These are 1.4Volt filaments designet to run off a dry cell. These are still available at some Hobby shops as they are used for the glo plug on model aeroplane motors. Do not even think about using 2V. "D" cell yes.

Looking at the valve specs I would not see the HT being above 90V. The filaments are polarised and should be taken into account as they are often part of the bias. Pin 2 of 1Q5 is F+ use that as a guide.

The set may have "C" Batteries or be back biased. We need more info.

I say that as I have had to repair the damage on an Airzone (in Silicon Chip) which was caused by cooking the back bias.

Marc

Ok....

The set is from 1941

I have checked the valves. All correct ones in correct places

It has had a recap by someone in the past....

The set is ALMOST! dead.

I hooked it up to my battery eliminator (1v and 90v) and all you get is static at full volume as the gang becomes closed. There is NO shorts in the Gang!

Do you have a copy of the 550P or 258G?

I have also tried tuning the valve set across the band with a transistor set near by. I cannot get any interference sound in ether radio.

I am lost at the moment without a diagram as what I find is a complete mess. All the wire is green and twisted around itself and other components.

I have made sure that I got the polarity of the connections right before I applied power so I haven't blown it!

Thanks

Daniel

Daniel

One is '40/'41, the other '46


1940/41 550P DW Portable 5 455 1A7G, 2*1P5G, 1H5G, 1Q5G AORSM '40/41 302 AORSM '46 328

1946 258G 258 Bat. DW Con. 5 455 1A7GT, 2*1P5GT, 1H5GT, 1Q5GT AORSM '47 432 TMRSM 94 49/7/0

I only have '37 to '40/'41.

I can send by email or send to Brad to post.

http://www.southcom.com.au/~pauledgr/STC.htm
(how old is your radio at bottom of page) says 511D is not in AORSM, but does say it is a battery radio, 1941, 455 IF.

Graham

Hi Graham

Amy info on them would be of a help. Please send what you have so I might be able to sort this out.

Thanks

Daniel

flakelartpg.com.au

OK Daniel, sent.

1V on the filaments is too low, there may not be enough emmision for the oscillator to start , yet alone other valves to run properly,

If it was recapped with paper caps, they will likely have to go, I have had two Midwest's pass through this year, that are now on their third (at least) set of caps.

Any electrolytics should be treated as suspect if they are older types. Static tends to indicate its audio may be working to some extent.

Be careful, with some power supplys earthing the set to mains earth causes them to go haywire. Use a 0.01 cap to mains earth. That includes the antenna.

Marc

Hi

Is it possible that STC produced kits (or Kits were made using STC parts) the Front end of my set dosnt resemble the cct that you sent to me.

I have been looking at RT&H dvd that I got a while back and have discovered what looks to be a closer match for the converter / IF amp. It is called 1941 portable set from Jan 1941.

My set uses the detector and audio amp that is in the STC but the front end is almost the same as the RT&H design.

Still... I cant get the thing to oscillate, I think that I might have a crook 1A7G?

Not having much fun!

Has Anyone got any more info on this set, I can't be lucky enough to be the only person to have one?

Is it possable its a kit or just a limited run made by STC?

I am going to draw up a full diagram this weekend.

I have even borrowed a sig gen to try and help me find why it wont osc.

Marcc and STC830 (and others) where will the best place be to start with it?

thanks

Daniel

Daniel,

There a number of portables at
http://www.hws.org.au/redlands.htm
Hopefully it is one of them.

Another STC 1941 portable at http://www.southcom.com.au/%7Epauledgr/STC.htm

Can you please post a pic.

Graham

Photos Here: Image Link

In the photos
1. The knobs are just some that I found in my bucket.. I know they are not the right ones. (If you have them and want to part with them let me know!)

2. Photo of the sticker on the back clearly states its a Code 511. THe valve positions are as marked

3. The speaker is a perm mag one and the cct was designed to have this because there is no HT connections like the ones with the electro magnet. this can be seen from one of the bottom shots of the Chassis.

4. Chassis Photos. You can see that it is complete and very tidy from above. Under is a completely different story!

5. I have replaced the 25μF cap that is across the 50Ohm bias resistor (this is the only electro in the set!)

6. All coils check out ok with my multi meter (Well DC anyway!)

I will try and draw up a diagram but things don't make sense. When I got the set the 50Ohm resistor was disconnected from the Speaker socket therefore no bias for the audio output valves.

I think there might be a cap in the wrong position done by someone who didn't know what they were doing.

As I don't have a valve tester or a spare valve I cant check out the 1A7G.

Pentagrids are not renown for being reliable.

Make sure that you use a filament voltage of 1.4 to 1.5V and polarity is correct.

Compare the circuit to a 510. All that is different is the output valve, the circuit may well be the same up to there?

Check the screen divider resistors have not gone high on the converter.

What drew you to the conclusion that the oscillator was not working?

Marc

I think that it is not oscillating because you only get sound when the gang is almost fully meshed. All slugs have been played with.

The cct is completly different. It has the 1P5 as a RF stage before the 1A7G, then the 2nd 1P5.

Drawing it up makes no sense. for example. The L.O. dosnt seem to be connected in a way that will make it oscillate. Maby I just cant follow what is happening in it.

I thought it was similar to a cct shown in RT&H Sept 1946 (page 39) but from what I can tell it is a little different because my set has an areal coil that connects the Loop antenna to the first 1P5.

Any Ideas??

I think that it is not oscillating because you only get sound when the gang is almost fully meshed. All slugs have been played with.

The cct is completely different. It has the 1P5 as a RF stage before the 1A7G, then the 2nd 1P5.

Drawing it up makes no sense. for example. The L.O. dosnt seem to be connected in a way that will make it oscillate. Maby I just cant follow what is happening in it.

I thought it was similar to a cct shown in RT&H Sept 1946 (page 39) but from what I can tell it is a little different because my set has an areal coil that connects the Loop antenna to the first 1P5.

Any Ideas??