The RCA phono connector doesn't seem to be a bad choice.  In fact, it is looks pretty darn good considering the cramped space of the rear apron of the KWM-2.  See:
https://wv0h.blogspot.com/2014/11/rca-phono-connector-characteristic.html
It might be worth noting that only one of the Collins supplied RCA phono cables for the KWM-2 was meant to be used as RF coax.  The rest are just for interconnecting the KWM-2 to other equipment with no regard to impedance.
Regards,
Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy


On Wednesday, November 29, 2023 at 10:47:17 AM CST, [email protected] <[email protected]> wrote:


The RCA was a bad choice but as Ken mentions Collins had a cult following. I would replace the RCA connectors with BNC connectors.

Mike N2MS

> On 11/29/2023 11:28 AM EST Ken <[email protected]> wrote:
>
>
> Yes.
>
> The ceramic-insulated RCA connector is far more likely to not introduce an impedance "bump" at the connection, unlike the SO-239 which does: but since the PL-259 is almost ubiquitous at the ends of RF cables, I suspect THAT is the main reason so many of us change our Heathkits to the SO-239.
>
> In the case of Collins owners, the initial cost of their rigs coupled with their overweening "respect" for Art's designs preclude them from "desecratimg" those rigs in the interests of convenience.
>
> In addition, of course, the PL-259-to-RCA converter is so un-reliable that it must be treated carefully to ensure constant contact, especially when the use of RG-8 sized cable is involved.
>
> Ken W7EKB
>
>
> Sent via the Samsung Galaxy S21 5G, an AT&T 5G smartphone
>
>
> -------- Original message --------
> From: Mike Morrow <[email protected]>
> Date: 11/29/23 06:11 (GMT-08:00)
> To: [email protected]
> Subject: Re: [Milsurplus] Nomenclature Tags
>
> The US military purchased the KWM-2A as the RT-718/FRC-93.
>
> The KWM-2A was introduced in 1961. Just by itself...no power supply, microphone, speaker, or any other accessories...it sold for $1,250. That is equivalent to $13,000 today.
>
> The Collins S-Line used RCA phono connectors everywhere except the RF output of the 30L-1 and 30S-1 amplifiers. For almost 60 years it has amused me to see ham "engineneers" very frequently replace the same quality ceramic insert phono sockets on Heathkits with SO-239 sockets in false belief that the SO-239 is a superior RF connector. Yet, one almost never heard of a Collins S-Line owner doing likewise. :-)
>
> Mike / KK5F
>
> -----Original Message-----
> From: Bruce MacMillan <[email protected]>
> Sent: Nov 29, 2023 12:05 AM
>
> A former co-worker used to work for Collins in Australia. He said on more than one occasion a KWM2 would have S/N's removed before it was "gifted" to a friendly party.
>
> Bruce
> M0SOE
>
>
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