Towertalk
[Top] [All Lists]

Re: [TowerTalk] Terminate unused ports on remote antenna switch?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Terminate unused ports on remote antenna switch?
From: "Lux, Jim" <jim@luxfamily.com>
Date: Tue, 10 Aug 2021 18:26:19 -0700
List-post: <mailto:towertalk@contesting.com>
On 8/10/21 4:40 PM, KD7JYK DM09 wrote:
For my situation, I am planning to install 1 kw dummy loads to the unused
ports and see what happens. I was hoping that someone would provide some
realistic input to this situation. And, of course, you are welcome come
here and lend a hand....

I'm open for some real suggestions.

Your idea of dummy loads is very good.  If something stupid happens, you have some protection.  I've used loads on unused ports of various devices since the mid-90's, and on very rare occasion, have mistakenly switched to an unused port while transmitting.  Aside from noting not what I expected happening (not hearing anything/nobody hearing me), there have been no other issues when doing this.

Personally, I recommend terminating the ports with a load that can handle full power.  Far better to be safe, than sorry!


That would get pretty expensive, pretty quick.   The MFJ-261, which takes 10W forever, or 100W for 15secs, is $35.  Stepping up to the MFJ 264 for $90, it takes 1.5kW for 10 secs, and 100W for 10 minutes. Plus the cost of a barrel connector or short jumper cable.

Terminating in a short (assuming your Tx will protect itself) at least limits the maximum voltage.  Into an open, you might happen to get a very high voltage, which might arc or otherwise couple to another port.

There is, of course, the time honored "big incandescent bulb" approach - 100W is about 100-120 ohms (hot) and 10 ohms cold. 60W is 160-180 ohms hot, 1/10th that cold.

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
<Prev in Thread] Current Thread [Next in Thread>