Re: {Collins} RCA Connectors

This topic seems to come up every now and then, and all arguments why Collins engineers might have chosen these RCA connectors are sound and clear ... except hat I never saw the most convincing one (at least for me): For the KWM-2 they also designed the 351D-2 Mobile Mount. The M-2 just slides in and mates with the connectors for power supply and antenna switching, as well as for power out (J1) and NB antenna (J28). The latter two most easily done with RCA connectors.

Just my 2 cents worth
Ernst DJ7HS

Am 2016-08-31 um 16:20 schrieb James R. Bartlett:
I have a TNC fitted to my 32S-3 and find it very good. like an N connector
but smaller.
Works very well and it is single hole fixing.
I think the TNC is a much neglected connector. In a lot of cases i would
prefer it to the BNC type
of connector, easy to fit as well. and 50 ohm..
Just my 2 cent worth

On 31 August 2016 at 15:04, Glen Zook via Collins <collins@xxxxxxxxxxxxx>

There are single hole BNC connectors that are the same diameter as the
hole in the KWM-2- series and S-Line.  However, r.f. wise, the RCA
connector is just as good as, maybe even better than, the BNC and
definitely better than the UHF series (SO-239).

I have told this story numerous times before, in all sorts of places:
 Here in Richardson, Texas, which was the "new" corporate headquarters of
the Collins Radio Company, there was a particular Texas Instruments Company
engineer, who worked in the R.F. Laboratory, who was also an amateur radio
operator.  He was constantly "making fun of" the fact that Collins, and
Heath, used RCA connectors for r.f. applications.  He was especially fond
of making these comments to the numerous local amateur radio operators who
were employed by Collins Radio.

Finally, several Collins employees challenged him to prove that the RCA
connector was inferior to other common r.f. connectors.  He accepted the

The engineer took numerous examples of the UHF (SO-239 / PL-259), Type
"N", BNC, and RCA connectors and tested them on frequencies ranging from
1800 kHz through 1296 MHz.  He did not make any tests on frequencies higher
than the 1296 MHz band.  A couple of weeks later, he came back, hat in
hand, with the results.

He found that all of the connectors were "OK" up through the 10-meter
band.  The UHF series started showing problems at 50 MHz and those got
worse at 144 MHz.  By the 432 MHz band, the impedance "bump", etc., made
the UHF series unsuitable and things got worse as the frequency increased.
However, the "lowly" RCA connector held its own along with the BNC and Type
"N" connectors all the way to 1296 MHz and he suspected that this would
hold true for even higher frequencies.  The only thing was that both the
BNC and RCA connectors were limited in power handling compared to the Type
"N" because of the size of the coaxial cable that were commonly used with
the connectors.  The BNC and RCA were used with RG58/U sized cable whereas
the the Type "N" connector could be used with larger diameter cables.

Glen, K9STH

      From: Bill Riches <bill.riches@xxxxxxxxxxx>
Cc: COLLINS@xxxxxxxxxxxxx
 Sent: Wednesday, August 31, 2016 5:50 AM
 Subject: Re: {Collins} RCA Connectors

I have replaced bad RCA connectors witha BNC panel mount.  Not as much of
a butcher job and a trouble-free connector.

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