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 Post subject: Polytronics Poly-Comm 2
PostPosted: Jul Mon 18, 2011 2:44 am 
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Location: Dayton Ohio
This seems the best place to put this, though its not a "Communications Receiver" per say.
It is a 2 meter AM transceiver from the early 1960s.

I was at the Milford Hamfest near Cincinnati in June and this little (well, little is relative) radio caught my attention and I couldn't let go. Happens to me alot don't you know :?
Evidently, Polytronics had a brief flash of glory, then went bust. They made a 6 meter version of this as well as a combo 6 and 2 meter which I understand didn't perform very well.

Probably their biggest business were CB radios.

Image

Looking it over, it is a triple conversion superhet with a crystal controlled "converter" in the front. The 1st IF is actually in the 6 meter band tuning 50-54 MHz. Which is then converted to 9.9 MHz and finally to 455 KHz. It also uses FIVE Nuvistors in the front end.

Interestingly, the Gonset Communicator IV also has a triple conversion receiver with tunable 1st IF as well. The Gonset does seem to be a bit more refined than the Poly-Comm 2.

Powering it up with a Variac, the receiver is troublesome with motorboating and other stray "birdies" . I will have to do a significant amount of contact cleaning, especially the Nuvistor sockets and I would prefer to replace the electrolytics. Problem is, there isn't much room in this set to stick new electrolytics under the chassis. ALSO, as this is 1960s, the multi-section electrolytic cans are much smaller per capacitor size than 1930s electrolytics were, so re-stuffing is going to be difficult, if not impossible. I'm not sure how I will accommodate this issue.

I notice that most of you are now using Caig Deoxit for contact cleaning. I've been whittling away at my reserves of Channel-Master Shield spray for contact cleaning which won't be around much longer. I see Deoxit doesn't have a lubricant, so what do you do, add a silicone spray after applying Deoxit? I feel controls should have a lubricant of some sort. CM Shield does a wonderful job! Too bad its long since discontinued :cry:

Anyhow, here is an ad from the July 1963 issue of QST for this radio,

Image

A larger version can be found in the gallery.
http://antiqueradios.com/gallery/d/1466 ... y1963a.jpg

I'm typically slow at restorations anymore as my job consumes most of my time and energy, which is so very unfortunate. I have many projects to work on and so little time... Oh well.

-Steve

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 Post subject: Re: Polytronics Poly-Comm 2
PostPosted: Jul Tue 19, 2011 4:09 am 
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Joined: May Wed 06, 2009 7:01 pm
Posts: 916
A thorough cleaning (with deoxit), some cap replacement, and some alignment go a long way in a Polytronics. Those nuvistors represent the height in tube technology, but they run hot and the pins and sockets must be clean. My 6 meter version has been the transceiver of choice for check in to the local weekly 6 meter AM net for the last couple of years. I place a computer fan on top at the back left corner of the rig to pull the heat out. I plug in an external speaker since the internal speaker can best be described as "tinny".

Pics of the Poly-comm 6 can be found here
http://www.ohio.edu/people/postr/bapix/Polycom6.htm

The Communicator II is the stand-by rig. The Polytronics has a full transceive VFO, a narrower bandwidth and is just a bit more sensitive, but both rigs do a fine job.

-- Rich


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 Post subject: Re: Polytronics Poly-Comm 2
PostPosted: Jul Tue 19, 2011 5:01 pm 
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Joined: Jan Mon 18, 2010 2:13 am
Posts: 22773
Location: Dayton Ohio
Thanks for the reply, Rich!
I figured those Nuvistor sockets might be troublesome as the second mixer made alot of noise if I wiggled it.

Another problem I found is the T/R relay. Its a 4PDT and some of the contacts are severely pitted. It wants to stick in the transmit position and not return without tapping.

I don't see any paper capacitors except one in the power supply section. Unless there were issues with the ceramics, I'll leave well enough alone and replace all electrolytics.

I'm glad to hear the performance of these are pretty good! It seems like a well built radio!

-Steve
KA8RIZ

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-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Polytronics Poly-Comm 2
PostPosted: Jul Tue 19, 2011 7:28 pm 
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Joined: Nov Sat 07, 2009 11:37 pm
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Location: Sayreville, NJ 08872
There were actually three versions of the 6 meter unit. Black knob, white knob, and black knob with added switchable preamp. The 2 meter unit had two versions, black knob and black knob with added switchable preamp. The latter wasn't around long before production finally ceased. All were drifty, heat generators, and with the obvious lack of document controls, many units in the field had undocumented changes. I still own the Measurements Model 80 generator, with the Polytronics metal tag riveted to the cabinet, that was used for final test and inspection on the manufacturing line.

Polytronics had several high end CB type models (23, Senior 23, 30, Pro) and a number of other models. They OEM'd the Osborne 320, Lafayette HB-333, and probably others in the early CB market. They were also into the CB Business band market with several products and accessories.

Pete

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