Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Tech Talk

Forum home - Go back to Tech talk

 Astor Mickey, unknown valves... What model? Help?!?
« Back · 1 · Next »
 Return to top of page · Post #: 1 · Written at 2:34:05 AM on 10 December 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

Hello fellow collectors.

I have just bought an Astor Mickey "Bread loaf" Style radio from the early fifties. It looks Identical to the "HQ" models as shown on the Radio Museum website, only dark brown, however mine has a "6G8G" in a Goat shield, that and the 6V6GT are the only valves with readable ID...

I am reasonably certain that the rectifier is a 6X5GT as the pins correspond to the schematics I have, but that 6G8G is odd-ball for those schematics and the first valve- detector? Is a little baseless valve, whereas the others are all octal, having bakelite bases.

Can anybody help me find the missing valve types and possibly the model number/ variation? I'm hoping to find a schematic as it has a few issues, hopefully minor. I think the rectifier tube is NVG, as with it unplugged, I have 205v at both plate pins, (3 & 5) yet when I plug it in, pin 5 drops to about 95v, so I'm guessing an internal short perhaps, unless somebody put the wrong rectifier in it, but I doubt it as it was sold as "working" but when it arrived it was making a loud buzz but no music or otherwise and the bulb in series in my extension cord glowed too bright for my liking, so I turned it off and re-capped it plus a couple of resistors..

Anyhow, if anybody has an Idea of what I actually have here, please let me know.

Thank you. Jamie.


 
 Return to top of page · Post #: 2 · Written at 5:24:12 AM on 10 December 2016.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1179

The schematics you require are already on this site:

https://vintage-radio.com.au/docs/astor-hq-1-4.pdf


 
 Return to top of page · Post #: 3 · Written at 3:23:12 PM on 10 December 2016.
Gfr53's Gravatar
 Location: Harston, VIC
 Member since 28 February 2009
 Member #: 442
 Postcount: 145

G'day Jamie,

The valve lineup for the HQ is 6A8G/6BE6G 6B8G 6V6GT and 6X5GT. Sometime in the production run a substitute was made for the
mixer. Not an unusual move when the store runs out of supplies and replacements are in short supply.

The 6G8G has the same pinout as the 6B8G and its characteristics are close enough to substitute for the 6B6G. Most likely done at a
repair shop.

Are you sure that the 6V6GT and 6X5GT are in the correct sockets? Both are in GT envelopes and could have found the wrong homes.
Just a wild guess but if these valves were swapped, pin 5 on the 6V6 is g1 and pin 3 is the anode. Would make an interesting experiment
to see what would happen if one was prepared to sacrifice a 6V6!!!

Astor HQ

1951 6A8G 6B8G 6V6GT 6X5GT
1952 6BE6 6B8G 6V6GT 6X5GT
1952 6BE6 6AD8 6V6GT 6X5GT


Cheers, Graham...


 
 Return to top of page · Post #: 4 · Written at 3:38:10 PM on 10 December 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

Well funnily enough Graham, when I first got it home, these valves were in fact in each others sockets, I'm guessing this is perhaps what fried the rectifier and possibly the 6V6...


 
 Return to top of page · Post #: 5 · Written at 4:22:18 PM on 10 December 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5239

Also beware of 6X5 that is a valve notorious for heater cathode shorting, in some forms of it.


 
 Return to top of page · Post #: 6 · Written at 9:43:37 PM on 10 December 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

Yes Marcc, I've ordered another one, as I have 205v at each plate pin without the valve plugged in, from the transformer, but with the 6X5 in, there's only 95v on pin 5, huge voltage drop, if that's not evidence of short, I don't know what is, anyway I've ordered new ones (6X5 and 6V6GT, just to be sure, and a 6B8G as I couldn't find a 6G8G anywhere and Franks Data sheet lists the 6B8G as a substitute, but I'll probably only have it s a spare, as I like chasing up spares if I can find them... Probably being a bit pedantic! But when the bug bites...


 
 Return to top of page · Post #: 7 · Written at 10:08:25 PM on 10 December 2016.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 2011

The valve lineup for the HQ is 6A8G/6BE6G

6BE6G ?? are you sure?

6B8G works fine to replace 6G8G.


 
« Back · 1 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.