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Author Topic: Heath RX-1/To re-cap or not  (Read 2807 times)
AB2MA
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Posts: 47




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« on: December 29, 2006, 06:41:57 AM »

Just wondering everyones thoughts on recapping this reciever.I'm sure the almost 50 year old caps are out of spec.Also the 100kc crystal tube is broken,Heath part #404-6.Any idea where to find one?Tnx,AB2MA
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KA5N
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Posts: 4380




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« Reply #1 on: December 29, 2006, 08:44:09 AM »

With recapping older gear the problem is not so much that the capacitors are out of spec as that certain types of caps become leaky (with voltage).  Certain types of caps don't go bad as often as other types.
Electrolytic capacitors get dried out and no long act as capacitors.  These usually need replacement. Ceramic or mica insulated capacitors have a very long lifetime and usually don't need to be replaced.  Caps
used for bypassing or audio coupling which were called paper capacitors (wax paper is the dielectric), or Black Beauty caps which have a ceramic case which is shiney black and others with orange or other colors often go leaky.  These caps will often have oil leaking out of them and should be replaced.
Modern electrolytics are much smaller than the original caps and when the metal can types are replaced one can often core out the guts and put a modern cap inside and retain the original look.
I would approach the task by replacing the electrolytics and audio coupling caps first.  Then the bypass caps of the Black Beauty variety.  Then I would carefully align the receiver and determine what, if any, faults exist and correct those.
The 100kHz crystal in a glass tube may be a bit hard to find.  A metal cased crystal can be used.  I am not sure but the pins on a metal can crystal may fit
the 7 pin miniature socket.
This should be a good project as the RX-1 has open construction and should be easy to get to all the parts.
Good Luck Allen
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AD5X
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Posts: 1614




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« Reply #2 on: December 30, 2006, 04:07:10 AM »

I do a lot of boat-anchor rebuilding, and I've found that re-capping right away gives you the least amount of grief.  I recap the electrolytics and paper/wax capacitors.  I haven't found any bad ceramic or mica caps in the dozen or so radios I've rebuilt.  I've also found that resistors that dissipate much power have generally changed quite a bit in value and also need to be replaced.

For radios where I want to keep the original look, I leave the stand-up electrolytics in place, and just mount the new electrolytics below the chassis on terminal strips (disconnecting the wires from the old electrolytics of course).  Where I don't care about the original look, I remove the electrolytic can and replace it with a piece of pc board material placed over the original hole, with new capacitors vertically placed on the pc board material.

A good place to buy high voltage caps is Mouser Electronics.

Phil - AD5X
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AE6RO
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Posts: 161




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« Reply #3 on: December 30, 2006, 04:19:46 PM »

I thought the RX-1 was a Mazda sports car equipped with the problematic Wankel rotary engine. No, I didn't start New Year's Eve early. AE6RO
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G3RZP
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Posts: 1145




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« Reply #4 on: January 03, 2007, 03:32:14 AM »

I've found that the small (1/4 watt) carbon resistors have generally drifted high, often by as much as 30%. Strangely, most circuits will accept it, but you do lose some performance, and I test and change them.
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AB2MA
Member

Posts: 47




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« Reply #5 on: January 07, 2007, 01:02:17 PM »

Thanks to all,I've decided to recap the rx-1.tnx,Stan
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