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 Kriesler 11-7 with ring-in valves
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 Return to top of page · Post #: 1 · Written at 8:11:37 PM on 13 April 2019.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 784

I have had for quite a while a Kriesler 11-7 with a broken dial glass. Having recently acquired a replacement, have now set about researching the radio.

The valve lineup stamped on the back of the dial plate is:

ECH35 6SQ7 6SK7 EL33A 6X5GT

which looks like the first of Issue 2 or 11-7F, referring to the documentation in

https://vintage-radio.com.au/home.asp?f=2&th=467#4129, Post 3.

All very good, but the valves fitted are:

6J8G 6SK7 6SQ7 EL8N 6X5.

I don't think 6J8 is a direct replacement for ECH35, and there does not appear to have been modifications made at the valve base.

EL8N is a bit of a rare bird, not appearing in any of my valve manuals, and appears to be the octal version of EL8 and is noted in radiomuseum as a low power version of EL3 (EL33, 6M6). So it might be a suitable valve, at least during restoration, if its characteristics are right. (Again there does not appear to have been modifications made at the valve base). Maybe it was used in a battery version of the 11-7 to conserve power.

However I am not a member of radiomuseum and I was wondering if anyone would be good enough to winkle out the data sheet which is available to members.

Or if anyone has any comments on this radio.

Thanks gents.


 
 Return to top of page · Post #: 2 · Written at 10:08:17 PM on 13 April 2019.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 3510

Not uncommon to find 6J8 & ECH35 swapped or 6J8 & 6A8 swapped The 6J8 pin1 is NC and ECH35 it is the "Metalisation" which is its shield pin1 is grounded. They do run in each others spot but bias is different & that also applies to how they behave.

Its a Heinz 57 varieties job possibly due to the war. 6M5 was the latter version yours is the 1948 version.

I can tell you all these wondrous things as I have worked on them, its In AORSM's and I have a copy of the "Technical Service Manual". Note that the grid stopper & grid leak on the OP valve will likely be cactus. Do check resistors as you toss all of the Waxed paper caps and electrolytic caps. Plate resistors on Det / First audio have an attrition rate: Do check.

Two in 8 normally have a good OP transformer. Crack a 9V battery across the OP transformer primary (screen & plate).


 
 Return to top of page · Post #: 3 · Written at 5:42:19 AM on 14 April 2019.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 784

Thanks for all that Marcc.

Good to hear about the 6J8 - it is not down as a replacement for the ECH35, either direct or otherwise in internet sources that I found, though I do remember that it has been used as a replacement, probably here.

I will certainly check the resistors as I go, but I want to make any necessary changes required by the valves fitted. Most but not all of the paper and electrolytic caps are already replaced, but none of the resistors, so will look out especially for your particular suggestions.

Have printed out the Technical Service Instructions given in the link above as well as other stuff from the net - pretty comprehensive with regard to the various models up to 11-7T. Dial stringing instructions and all so am pretty well set up there but would be happy to have your "Technical Service Manual" if you wouldn't mind posting or emailing.

Have made a list of the valve lineups up to T in the act of finding out if EL8 is mentioned anywhere, which it isn't. Some minor discrepancies there which I will discuss when I post it.

Haven't taken a meter to it yet but the transformers and choke will be the first to be checked as they could be a show stopper for a while. 6" speaker cone in a sorry state but repairable I think if it passes your battery check.


 
 Return to top of page · Post #: 4 · Written at 7:18:31 PM on 14 April 2019.
Normf's Gravatar
 Location: Erowal Bay, NSW
 Member since 19 June 2018
 Member #: 2256
 Postcount: 65

Hi STC830
Have a copy of the circuit for 11-7F issue 2,


 
 Return to top of page · Post #: 5 · Written at 5:51:22 AM on 15 April 2019.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 784

Thanks Normf.


 
 Return to top of page · Post #: 6 · Written at 3:28:36 PM on 15 April 2019.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1242

Kriesler in particular was known for swapping valve types around due to supply shortages.


 
 Return to top of page · Post #: 7 · Written at 4:16:34 PM on 15 April 2019.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 316

And the opposite Ian, when they had too many of one type.
For example the last of the Kriesler valve radio’s used 6GV8’s as an audio output valve.
Ex B/W TV production.
JJ


 
 Return to top of page · Post #: 8 · Written at 6:31:42 PM on 15 April 2019.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 3510

Its amazing to see where some valves end up. 6BL8 frequency changer was a widget that ended up in RF & Audio 6A6 was a bit like that & HMV used an #807 as an audio OP & the switcher 6CM5 was used by Philips as a Line amp OP often with 4 to 6in PP.

Kriesler 11-7 Technical Service Instructions


 
 Return to top of page · Post #: 9 · Written at 2:17:11 PM on 16 April 2019.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1242

Yes JJ, those 6GV8s were the ones rejected on the TV line due to picture roll during warmup (a well-known issue with the 79-23). Philips wouldn't replace them (claimed they were in spec) so they got used in the mantle radios instead.

Production of those radios ceased not long after the all solid state 49-7 chassis, having proved itself in a 17" portable, was migrated to the full size B&W TVs.

Marc, the 6BL8 was promoted as a do-anything valve with lots of application circuits released by Philips and Mullard in the late 50s. Look at the Astor BSK chassis! I particularly like the 6BL8 as a video output circuit, with the triode serving as a cathode follower driving the CRT cathode. Elegant and efficient. Astor and Pye both used this circuit. Philips used the same idea with transistors in the KT3 and KL9 colour chassis.

In the immediate post-war era valve makers were awash with 807s and so they dropped the price to 2 shillings and sixpence and released appnotes on how to use them for other things. Some early TV transmitters used lots of them in parallel.

The 6CM5 was/is far from ideal as an audio power amp unless you don't care too much about distortion figures, which is why they found their way into PA amps.


 
 Return to top of page · Post #: 10 · Written at 6:57:04 PM on 16 April 2019.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 5267

Document uploaded to Post 8.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 11 · Written at 5:37:08 AM on 17 April 2019.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 784

Thanks for the data, Normf & Brad.


 
 Return to top of page · Post #: 12 · Written at 11:47:52 AM on 19 April 2019.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 784

Re the 11-7E, been looking through old HRSA Radio Waves for articles on the 11-7 in case there are any wheels that have already been invented.

As far as wheels already invented two encounters in Radio Waves with 11-7s with no silence on zero volume control setting. This is due (at least with E & F) with component problems around the 6SQ7, particularly the cathode resistor bypass capacitor.

(Above removed from Post 6 of "Kriesler 11-7 valve lineups by model number" thread to here to remove confusion.)


 
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