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Re: AM antenna switch for 5kW ?
To: CRTech <crtech@crtech.org>
Subject: Re: AM antenna switch for 5kW ?
From: Kevin Kidd <kkbroadcastengineering@gmail.com>
Date: Sat, 12 May 2018 15:08:12 -0500
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In-reply-to: <alpine.WNT.2.10.1805111649050.3300@Lyle-Dell-D630>
References: <alpine.WNT.2.10.1805111649050.3300@Lyle-Dell-D630>
Lyle,

At MW you can get by with almost anything that allows the load to look something close to 50j0.  The newer solid state, no knob transmitters are much more finicky about load than any tube TX but as long as you keep the unshielded parts of the connections to a minimum, you should be able to use almost any kind of relay or switch that will handle the current and voltage.  Contact gap is an issue if the RF voltage is expected to be high...

I have recently seen manual ham antenna switches rated for full legal ham radio power used to switch between 1kw transmitters.  I have also recently seen Potter & Brumfield relays used in place of and in conjunction with, KTL RF contactors in the same cabinet...

AM is pretty forgiving as long as you use good grounding and engineering practices.  Keeping someones fingers out of the hot and moving parts is almost more of a problem.

Kevin C. Kidd, CSRE/AMD
Lawrenceburg, TN
AM Ground Systems Company  -  WD4RAT
kkidd@kkbc.com  --  866-22-RADIO -- 866-227-2346
www.amgroundsystems.com

On Fri, May 11, 2018 at 7:20 PM, RADIO DOCTOR <lylehenry@fastmail.fm> wrote:
What remote control switches are being used for AM nowadays?  Shielded for coax or open relay(s) on a panel/board?  Controllers?  Automatic?

4 Port would be nice so dummy load would be connected to the transmitter that's not on the air.

The transmission line is a 1/2" late 1980's version of the current 1/2" CableWave (RFS) LCF12-50J.

What's best for jumpers?  Should I bother with connectors or just wire it up?  Transmitter will probably be 7/8" EIA output, but DIN connectors might be nice for hooking everything together.  Is there a 7/8" EIA to appropriate size DIN adapter.  I've never used DIN connectors anywhere.

Being an FM Guy, I've rarely dealt with real AM.  Always tried to keep AM at least 50 dB down :)

Thanks mucho for your comments and suggestions.  ...Lyle


FMeXtra digital SCA systems - encoders and receivers
SCA/FM/FMeXtra radios: fixed & tunable-wood cases-nice sound
Sidekick SCA generators - 67/92kHz-checked and calibrated
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  Lyle Henry, CPBE  THE RADIO DOCTOR  K9DKW  Los Angeles, CA
SCA Consultant:  Brazil, China, India, Mexico, Taiwan, SE Asia
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References: AM antenna switch for 5kW ?
(RADIO DOCTOR <lylehenry@fastmail.fm>, 12 May 2018 00:20:15 -0000)
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