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-   -   Motorola 77X-M22 (http://www.videokarma.org/showthread.php?t=260088)

bandersen 11-22-2013 11:36 AM

Motorola 77X-M22
 
I could resist hitting the $39 BIN on this blonde AM/FM Motorola circa 1948.

http://farm3.staticflickr.com/2865/1...3f77e12c_c.jpg

http://farm6.staticflickr.com/5479/1...02958c77_c.jpg

It uses a variable cap for AM and three variable inductors for FM.
http://farm6.staticflickr.com/5512/1...84048da7_c.jpg

It's been partially recapped in the recent past judging by the caps used. It works fine on AM but only got sound for one brief instance on FM. Wonder why they didn't replace all the paper caps ?
http://farm4.staticflickr.com/3814/1...85eb45ba_c.jpg

Not only does it look nice on it's own, it's also a great match with my 1948 blonde VT-71 :D
http://farm8.staticflickr.com/7394/1...0a39ddbe_c.jpg

egrand 11-22-2013 03:40 PM

Very nice! Lucky for you I didn't see it first. That's the nicest one I've seen.

bandersen 11-22-2013 04:09 PM

Thanks. It turns out I had my variac set to only 105 VAC :o I brought it up to 117 and the FM started working just fine :)
http://farm6.staticflickr.com/5535/1...be5a4ab5_c.jpg

bandersen 11-22-2013 04:39 PM

I spoke too soon - the FM band is dead again. I definitely need to do some troubleshooting :yes:

dieseljeep 11-22-2013 07:57 PM

Quote:

Originally Posted by bandersen (Post 3087804)
I spoke too soon - the FM band is dead again. I definitely need to do some troubleshooting :yes:

I just looked at the schematic in Riders 18. It's interesting that the FM IF frequency is 4.3 MHZ, like the pre-war FM sets. The coverage on your set is 88-108 MHZ. The schematic shows a 12AT7 as a 1st and 2nd converter.
Your pictures show where some of the caps were changed, but not all, including the 'lytics.

bandersen 11-22-2013 08:55 PM

I got the radio from this ebay seller: http://www.ebay.com/sch/Radio-Phonog...&_ssn=akachuck

Quote:

This comes to us from the estate of a lifelong collector in the San Francisco Bay area. Watch our listings for thousands of interesting items as we continue going through this place which has been stacked to the ceiling for years!
So perhaps that previous owner did the partial recap :scratch2: For sure I'll replace the rest when I get a chance.


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