[Drake] R4B antenna connector

Sun Jan 9 21:09:32 EST 2011

My complaint with RCA connectors isn't with the RF characteristics but instead with the physical quality and overall quality has to take into account all relevant characteristics.   Although I don't plan to modify the connectors on my gear I sure wouldn't undo someone else's change to a BNC connector.  I have no problem with RCA connectors on my audio equipment that rarely gets moved around or unplugged but  I am certainly glad Tektronix and HP didn't use RCA connectors for their test gear!  :)

Rodger WQ9E

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From: Glen Zook <gzook at yahoo.com>
Sent: Sunday, January 09, 2011 7:34 PM
To: WQ9E at btsnetworks.net, Charles Ring <w3nu at roadrunner.com>
Subject: Re: [Drake] R4B antenna connector 

Actually, the RCA connector is better than a UHF (SO-239 / PL-259) connector and just as good as a BNC up to at least the 1296 MHz band.

Collins, Heath, Drake, etc. used them in their amateur radio equipment and Motorola and General Electric used them in their commercial two-way equipment.

A "ways back", there was an amateur radio operator here in the Richardson, Texas, area, that was employed in the Texas Instruments r.f. laboratory as an engineer.  The "new" Collins Radio corporate headquarters was also here in Richardson.  The TI engineer used to "make fun of" the fact that Collins used the RCA connectors.  Finally, several of the Collins engineers dared him to make some scientific measurements of the RCA connectors.  The TI engineer took them "up" on the dare.

He made measurements on the UHF connectors, on the RCA connectors, on Type "N" connectors, and on BNC connectors from the 160 meter band through the 1296 MHz band.  These measurements included losses, impedance "bump", power handling capabilities, etc.  He was very surprised at the outcome.  The UHF connectors did pretty well up through 30 MHz, then the performance started to drop off considerably as the bands increased in frequency and by the 70 cm band they had dropped off in performance as not to be suitable for any serious work.  The other 3 connectors all performed very well up through the 1296 MHz band where he stopped the experiments.  The RCA connectors did at least as well as the BNC and Type "N" connectors with the only limitation being that the Type "N" connector could handle more power.  But, at the power levels that Collins was utilizing the connectors their performance was well beyond even being satisfactory.

The TI engineer came back, hat in hand, and admitted that Collins had made a good choice in using RCA connectors.

There have been other experiments made under laboratory conditions that show the RCA connector to work very well in r.f. applications so long as the power level is kept below around 200 watts to 250 watts.  Now the connectors used were NOT the "el cheapo" plastic RCA connectors that come from Radio Shack and other "consumer" outlets.  They had metal shells and were definitely of better quality than the plastic types.  Metal shelled RCA connectors are readily available from Mouser and other suppliers at very reasonable prices.

Glen, K9STH

Website:  http://k9sth.com

--- On Sun, 1/9/11, Charles Ring  wrote:

I agree. I really dislike using RCA connectors for RF, a bad old practice afaik used only on ham equipment to save money. I have replaced some with SO-239 and some with BNC.

On 1/9/2011 6:42 PM, WQ9E at btsnetworks.net wrote:

I have a couple of R-4B receivers (and several others of the 4 line family) and have worked on several more and all had RCA jacks.  I have never seen any documentation for a different jack on the R-4B although I vaguely recall that some of the SPR-4 receivers were sold on contract with a BNC antenna connector.  I am fairly certain your R-4B was modified by a previous owner.

I would just leave it as is since the hole probably was enlarged to take the BNC connector AND the BNC is a better connector anyway.  I especially dislike the RCA antenna jacks used on some Heath and Collins gear.

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