Hi, I restored the stereo 6DX8 PP amplifier chassis of an Australian made radiogram a few years ago, but was not able to identify the maker/model of the radiogram at the time as I just had the 'innards'. If anyone can tell from the two linked photos then that would be much appreciated.

The chassis is stamped 1569. The output and power transformers are marked 4156 0C8 (16K PP; 16Ω secondary) and 3261 0C8 (0-240V; 260-CT-260 ?mA, 6V3 5A), so could be custom A&R. The various identifiable part date-codes seem to indicate a circa 1969 manufacture.

https://www.dalmura.com.au/static/$_57a.jpg
https://www.dalmura.com.au/static/IMGP0875.JPG

Ciao, Tim

It looks familiar to me ,but I can't put my finger on it ! I think it's HMV ,, tonight I will Look through my books and see if I can identify it ..I'm sure it's HMV ....pete

What does it say at the top left corner of the front panel? (it's rather blurry there)

What is the valve line-up?

Just had to check - LHS top says 'Input RH', and below is 'Input LH', and in between is MICROPHONE and TAPE RECORDER.

Line up is 6AN7, 6N8 and 12AX7.

Missing a couple of valves, maybe four. 12AX7 is a double triode so if its stereo where are the out put tubes? Other chassis perhaps?

Some manufactures did like certain valves HMV liked 6M5 as an output valve as well as 6BM8.

I can see at least 7 valves in the first photo - what valves are in the back part?

Sorry - the initial post says its a stereo 6DX8 PP amp chassis - so yes a quad of 6DX8 (and a rectifier socket which didn't come with a valve, but was likely a 6V4, and I've restored it with a 6V4).

6DX8 is normally used as a video output valve in TVs, I wouldn't have thought it would have enough power for an audio amp. But I guess the manufacturers will try anything.

Thanks for the valve list.

I used a 6DX8 as the audio output in my 3" TV set.
It is just a triode pentode meant for linear uses.
I used a 100volt to 8 ohm line tranny for the output.
The wattage output would depend on the working voltages in the chassis.
I wanted about 1 watt to drive a 5" speaker and it walked that in!
They probably had a warehouse full of 6DX8's for TV use, so used it for anything else.

Fred.

I looked through my books last night and found nothing with that face plate and chassis so whatever unit it came out of was not a popular model as I have photos of most units from the 60s to early 70s.....

Yes I looked at all the radiogram photos I could find, and still look around if I notice a radiogram show up on ebay or facebook.

The amp chassis was quite nice to restore and re-purpose, with enough chassis face area to add two input jacks, two dual-gang pots for post PI volume, and two speaker jacks.

The Miniwatt datasheet has an audio class AB PP section, so audio wasn't an uncommon use for 6DX8 and its 4W plate dissipation rating. Datasheet rated audio output was 5.4W for PP in to 17.5kohm load (which was a bit higher than typical 6M5). I got a reasonable 3W clean from 90mVrms input, and configured it to over-drive nicely.

One thing worth mentioning is don't target the visual search on a black face plate which is easy to do.
Many units had mostly silver but a hand full of blacks are made.
The 1197 did that ,where 90% that I've seen were silver and few odd black ones about the place so other manufacturers would of also done the same ....

It's a GE. I remember that model. Not common. Made in the Enfield factory. Successor model was all solid state.

A GE ! That makes sense,They had some odd ones... There is one model that brings big bucks I will get the model and post it here.

This looks like the one.

Maybe upgrade the 6V4 for a 6CA4.

General Electric RS8V1C Circuit Diagram