[TowerTalk] Terminate unused ports on remote antenna switch?

[Lux, Jim]

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.