Hello all.

I have a Kriesler radio for which I would like to identify the model number. In the great Australian tradition it has no identification on the chassis or cabinet whatsoever, only a serial number. The valve line up is 6F7, 6K8G, 6G8G, EL3NG, 80. It has an RF stage and is dual wave. There is nothing in the AORSMs that match. The ARTS&P transfer has the letter "G" on it so it is 1940/41. I've sent a photo to Brad to be included.

Regards, Stuart

The 80, the 6G8G and the 6K8G are at home in the Kriesler 3K series of that era. Is there a chance that the others are random substitutes to fill the sockets?

Photos pending - FTP is playing up whilst I am out of town.

6F7 (6P7 Octal) Is a Triode remote cut off Pentode. RF / AF amp :Wiring will be interesting.

It would be more common to find the 1st RF as a 6U7 and similar for the first IF. 6K8 is also unusual as the most common in SW was 6J8 or ECH35. Having said that 6A8, 6J8, & 6K8 will often run in the others place, with not exactly the same behaviour.

This could also be a war time mod, or someone adding double conversion? 6F7 is a 7 pin valve. #80 is UX4; EL3NG, 6K8, 6G8; Octal.

Hello GTC.

Although there is no valve line up diagram, the valves in it do make sense to me; 6F7 = RF amp., 6K8G = F.C., 6G8G = I.F. amp. and detector/AGC rect., triode of 6F7 = A.F. amp., EL3NG = Output, 80 = power rect. This general valve function line up has been used before on Australian made radios; i.e., Stromberg Carlson 536.

The only common valves that would go in the first socket are the 6A7 and the 6B7, but the radio doesn't need another F.C. or another valve with diodes. A 6V6G or a 6F6G could go in the EL3NG socket, but the extra gain of the EL3NG would be a help, since the triode section of the 6F7 only has low gain. I haven't pulled the chassis out as yet to inspect the output valve bias resistor value, or that of the back bias resistor.

Cheers.

I had a browse in AORSM & came up with a positive. Have a look at 3K75 / 3K80.

This is an AC / DC set and uses that combination up to the OP. So it is very likely a transformer variation of it. Which would then explain #80 & an EL33N (bias is different for a 6V6).

My AORSM Vol 3, page 203 shows the line-up for the 3K75 and 3K80 as being: 25Z6G, 6F7, 6K8G, 6G8G, 25L6G

It is a very poor scan.

Vol 4, page 191 shows the line-up for model 3K75 as 25Y5/25Z5, EK2G, 6U7G, 6G8G, 25A6 and 302 barretter.

Photo uploaded.

We are looking at page 203; I am not particularly phased by the two 25V valves, remember that this one has no transformer. However, it is of the utmost simplicity to power it with a transformer, use a #80 & instead of a series string & use all 6.3V valves & change the OP tube.

My point is that the front end may well be the same? & The OP & rectifier are not rocket science.

remember that this one has no transformer

Stuart hasn't made that clear as yet. Assuming that the line-up he gave is correct for the set, then I'm expecting a transformer.

Stuart: I note that your own entries for the table model 3K75 on Radiomuseum mention versions with and RF stage (1939) and without (1940?).

I am assuming that this is wartime production and using the same design would be a factor. I am assuming in that as there is an #80 that it has a transformer. Most of the vibrator types did not use those valves, but with the voltages & circumstances a 6V & 32V Vibrator variant is not inconceivable, based on the transformer version, & that was done.

Thanks for your replies. Yes, I'd already considered that this might be similar to the AC/DC models mentioned, but I specifically wanted to know the model number, so I could add it to Radiomuseum.org. It does have a transformer. Anyone know?

It is quite clear when you look at the model listing, that there was a whole lot of chopping & changing going on, probably to maintain production in some form. WD had a habit of scarpering off with 6B8 & others, which I suspect is responsible for a reverting, in that period, to earlier based valves.

If you look at 3K00 it looks to be reflexed but has an 80 & 6AG6: So a reverse engineer may reveal a very similar front end coupled to a continually varying PSU & a bit of tweaking.

I have in the past repaired a set where the RF was one years & the audio the next model, so anything goes during the War. HMV actually has a mod on one of its sets because of WD & changed the circuit to accommodate a procurable, Philips valve.

One of the things I use my AutoCAD for is assisting in reverse engineering sets with no circuit like STC chassis 59. The first thing to create is a layout diagram ( Autocad for sockets etc). It's tedious, but if you want the wiring diagram........................

Hi Stuart, as soon as I saw the photo I recognised your set as the same breed as the 3K15 Kriesler I did a bare chassis rebuild.
That's in the special projects section on this site.
Cheers, Fred.

Model 3K15 published line-up: 80, 6K8G, 6U7G, 6G8G, 6V6G