[Milsurplus] URC-35

[paul alexander]

Eugene--

The symptom of tripping the breaker could be caused by a bad DC-DC
converter.  I would pull that module and check the two power
transistors on the bottom of the module.  While you have the DC-DC
converter open, look at the circuit boards and see if you have some
burned areas.  I would also look for shorts on the output of the AC
supply line.

The URC-35 and WRC-1 DC-DC converters were not compatible and I do not
know why they were made this way.  My guess is the two design teams
did not talk to each other.  I agree this is counter intuitive, but,
being a design engineer in a company where the left hand does not talk
to the right hand, I understand how things like this happen.

Yes, the converter is repairable, with difficulty.  The difficulty
lies in the inaccessability of the converter while installed in the
radio.  See my previous post.

Yes, there is a converter made specifically for the URC-35.  I cannot
recall part numbers, as that was too far back in my memory.  It was
nearly impossible for us to get them in the Navy and it will probably
be difficult for you to get them, too.

Feel free to ask questions on or off list; I will help as much as I can.

Paul
wb9ipa



Message: 3
Date: Mon, 18 May 2009 17:03:17 -0400
From: "W2HX" <w2hx at w2hx.com>
Subject: Re: [Milsurplus] URC-35?
To: "'Joseph Pinner'" <kc5ijd at bellsouth.net>,   "Military Radio Radio"
       <milsurplus at mailman.qth.net>
Message-ID: <000001c9d7fc$153b7b80$3fb27280$@com>
Content-Type: text/plain; charset=us-ascii

Question on this radio. I have one too. Mine was also kinda working (no side
band reception but AM ok) and it quit. I haven't even opened her up yet, but
this DC converter failure sounds interesting.

Can anyone confirm if a symptom of the amp power switch refusing to switch
on (keeps tripping the breaker) is a typical symptom of DC converter
failure?

Also, question for Paul: You mentioned that the DC converter used in the
WRC-1 is insufficient for the URC-35. If I were to look out for a
replacement DC converter what would I look for to avoid or look for to get?
Is there a particular part number I should try to get?

Also it would seem counterintuitive to me that the WRC-1 supply should be
insufficient for the URC35. With a separate Tx and Rx of the WRC-1 I would
have thought that it would have higher power requirements and thus a
sturdier supply.

BTW: Are the DC-DC converters repairable? Or is it best (or even possible)
to just get a replacement?

73 Eugene W2HX