[ARC5] Collins stuff and RCA jacks

[Richard Knoppow]

----- Original Message ----- 
From: "Geoff" <geoffrey at jeremy.mv.com>
To: "Howie DeFelice" <howied231 at hotmail.com>; 
<arc5 at mailman.qth.net>
Sent: Tuesday, May 14, 2013 6:31 PM
Subject: Re: [ARC5] Collins stuff and RCA jacks

    No one has mentioned the spring contacts of the RCA 
plug, the body of the male and center contact of the female. 
Even dicounting corrosion both tend to become stretched with 
use and make poor contact. While its possible to compress 
them they usually have become fatigued and won't hold the 
compression very long.  RCA connectors have been shown many 
times to have good electrical properties but were never 
intended to be heavy duty.  I think they were originally 
designed for auto radio use or something similar (Carl may 
know for certain).  In some applications they are not 
connected and disconnected much and will  have a long life. 
However, they are no where near as rugged as NC/BNC/UHF and 
similar connectors. For high power there are better 
connectors than any of these but they are not very common.
    A more modern example of a very simple connector that 
has good electrical properties is the common F connector 
used on TV cable.  These work up to several hundred megaherz 
but are not very rugged. There are quick connect versions 
without the threaded section but they are not very reliable, 
at least in my experience in a network TV plant. I don't 
know if there is a 50 ohm version but the integrety of the 
cable is preserved throughout the connection so probably the 
same connector would work for both 75 and 50 ohms.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com

>> Having spent most of my life as a field engineer, my 
>> experience has been that  the chassis end of a BNC 
>> connector is not very rugged unless the cable end is 
>> plugged into it. It was routine to find the chassis end 
>> bent to the point of not being usable. In extreme cases 
>> it was just broken off at the base. It's hard to beat the 
>> ruggedness of an RCA connector.
>>
>>
>> -Howie AB2S
>
> RCA rugged? Thats a real stretch.
>
> Heathkit had so much trouble with them in the SB-200 that 
> they issued a field bulletin about replacing with a BNC 
> and in later production went with a SO-239. And yes a 
> ceramic chassis mount was used.
>
> Who cares about impedance bumps at HF since the PL-259 is 
> such a small fraction of a wavelength to be meaningless? 
> The same holds at 6M and 2M even at the 1500W level 
> providing some cheap import POS isnt used for the male and 
> female. The connectors barely get warm on 2M even in a 
> contest.
> At 222 MHz the impedance difference is noticable on a Bird 
> and when I went from 400W to 1500 it was strictly mil spec 
> N's.
>
> Carl
>
>
> Ive found the RCA's to be a constant source of problems 
> when servicing Collins, Drake, Heath, and other gear using 
> them.  For the aggravation they give with seating and 
> corrosion it is better to replace them...they werent 
> designed to be still used over 50 years later.
>
> Just my 2 cents from someone who has been steadily fixing 
> this stuff since they were new.