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Re: [TenTec] proper caps for Omni V?

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] proper caps for Omni V?
From: Joe Roberts <jroberts@io.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 20 Feb 2008 01:21:55 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Look for 105 deg C, Low ESR, High Frequency caps. Find caps designed for 
bypass and decoupling in digital circuits--switching power 
supplies,logic boards, and the like.

Check the Mouser catalog--I think they are currently listing some 
Chemicon brand parts of this nature. I also used a bunch of Nichicon 
Type PL which is a now obsolete series with decent specs.

Many manufacturers provide "motherboard" grade caps--Rubycon MCZ, Sanyo 
Oscon...best place to find these is ebay surplus. Search "motherboard 
cap" You won't find these in all required values but for some of the 
higher C decoupling caps, like at the input to the logic board, these 
would be great to use.

There is often some leeway in cap value but this needs to be determined 
on a case by case basis. Obviously, QSK and AVC time constant caps, for 
example, must be the same value as the original (unless you want to 
change the time constants--not a bad idea for SSB AVC).

While you are working on the IF/AF board, do the LOGIC BOARD and the 
DISPLAY DRIVER board. In fact I'd do those first. The reduction in 
internal noise when you redo these boards with good fresh modern caps is 
remarkable.

These are a few electrolytics behind the heatsink...make sure you 
replace those also using good 105 deg C parts.

A few other Omni V owners on the list have done this rebuild and all 
report fantastic results. With modern caps, you can make that radio 
better than new. Except for the recently discussed shortcomings in 
computer interface, I'd put the rebuilt Omni V on the table next to 
anything.

Joe N5KAT





Steve Berg wrote:
> 
> I have taken the Omni V off the desk since I got the Corsair II PTO back 
> from Ten Tec, and I want to replace the electrolytics on the audio/IF 
> board.  It has been many years since I specified a capacitor, and those 
> were chip ceramics, so what brands and models have the appropriate 
> qualities for this sort of service?
> 
> Thanks,
> 
> Steve WA9JML
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
> 

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