From: Garey Barrell 
Subject: Re: [drakelist] R4 and T4X injection issue, transceiving


Gene -

RG-58 is 28.5 pF per foot, giving a total capacity of 
about 90 pF for the 38" length of the Drake cables. 
I've never tried it, because of it's size and bend 
radius compared to the audio cable used for the rest.

I know it works for the S-Line, and is what I use 
there.  But the S-Line was designed for RG-58 cable in 
the RF circuits.  The Collins cables are 48" long also, 
which makes the bend radius less of a problem.

RG-58 will probably work ok for the Drakes as long as 
you do the Injection alignment with the rigs connected.

Belden 8421 audio cable is 16 pF per foot and works 
just fine.  It has a foam dielectric and is the same 
size and flexibility as the audio cables.

73, Garey - K4OAH
Atlanta


Gene McCalmont wrote:

> Good Morning Ken
> Garey Barrell's suggestions (K4OAH) are right on target. I too have
> experienced the same problem as have most of us on the list. Another option
> you may try is to substitute your current injection cables with RG-58.
> Mouser sells these cables with molded RCA plugs already attached. Although
> the capacitance is not quite on design target, it's close. Switching to
> RG-58 and repeaking the set cured my problem nicely. I also use this cable
> combination on all of my Collins equipment with equally good results.
> 
> Good luck and 73 de
> Gene
> 
> W5DDW
> Gene McCalmont
> 270 Oakridge Road
> Argyle Texas 76226
> (940) 464-4474 Office
> (214)-502-0322 Cell
> 


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