March 4, 2010 at 6:05 am #1658Gerry O’HaraKeymaster
Just finished work on an RCA GR10 (RCAF version of the AR77). The work comprised a good cleaning, re-capping (using mainly using NOS Aerovox caps – all pre-tested ok), replacing a couple of resistors that had drifted significantly out of tolerance, cleaning the switches with De-oxit, installing a line fuse, etc. It is now burbling away happily on WWV at 5MHz on a bit of wire in the basement on soak test before I check alignment fully (it is not too bad – <100kHz out on 5MHz WWV). I have not fully tried it out on all bands, but it is better than I thought it would be considering its relatively simple circuit. The twin shutter dials (main tuning and bandspread) were a bit fiddly to get working correctly – they were gummed-up with hardened grease and dirt, plus, if you look at the vertical mounting plates on the photos below, plastic residue from the dial ‘glass’ (Plexiglas). Once working, I noticed it was a bit ‘deaf’. This was traced to the first IF stage – it was a strange fault that took a little time to resolve: zero volts on the screen grid and the S-Meter not working. After a frustrating hour or so checking associated resistors and capacitors and the tube, the problem was evetually traced to a small sliver of metal that was shorting the tube socket pin to ground (very frustrating as it was almost invisible). Once it was removed, the S-Meter functioned correctly and the gain came up to what I would expect. Overall, the set is not in too bad a shape – I decided to leave the old, yellowed Plexiglas dial glass in place as it adds real ‘character’ to the dial, vernier and S-Meter (check out the photos) – you get that lovely cosy feeling in a darkened room while tuning around the bands. The crystal filter works a treat and CW performance is pretty good, but it is best on AM – really good audio quality. Final tune-up and a little cosmetic touch-up on the front panel and I am done.
Click on the photos for a larger image.
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Download DSC00189 [1024×768].JPG. (Caution: This file may not be virus scanned.)September 22, 2011 at 8:08 pm #2543JSTvintageForum Participant
Just picked up 2 of the AR-77’s from Tom in Welland.
Haven’t had any time to check them out this week but hoping on the weekend.
Other than the cabinet style construction instead of a rack mount of yours, the only obvious difference is the Red color filters over the frequency scales.
One receiver is missing the shutters for both dials. Any chance you have any spare parts?
I also have a real restoration project with an ACR-175 that was stored in a garage and invaded by bugs and perhaps even mice.
It’s now clean but rusty so I’m thinking of a complete chassis strip down and replacement of all tube sockets.
Before I go that far, I need to have a closer look at the dial mechanism and see if it is worth continuing.
I suspect that the same dial was used on the tabletop consumer radios of the same vintage, so maybe some parts are still around?
Great article on your work.
John VE3PCNSeptember 25, 2011 at 9:54 pm #2558rfenergyForum Participant
I think I worked on this model of Rx up in Holberg in the early 1960’s.If it is the model I am thinking of,they only covered the top end of the BC band.
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