[Milsurplus] OT: Coaxial Relay ratings

[W2HX]

Ok thanks, everyone. So I plan to switch before an antenna coupler (tuner) so the relay should see nearly 50 ohms in each direction (if the coupler is doing its job right).  In this case, do you think this 300W at 3GHz relay will suffice?

-----Original Message-----
From: Nick England [mailto:navy.radio at gmail.com] 
Sent: Friday, October 17, 2014 8:17 AM
To: Bob Camp
Cc: W2HX; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] OT: Coaxial Relay ratings

Right. SWR is THE major factor. One kw at 50 ohms is just roughly 250v at 4 amps. No big deal. I have a 500w Navy xmtr that uses a garden variety microswitch in the antenna lead. 

As Rob pointed out, if you are switching off-resonant antennas, open frame relays are the way to go as you may be talking several kilovolts. 

I suspect even at 30mc the impedance bump of a relay is no big deal. 

Nick
(phone email acct)


On Oct 17, 2014, at 7:18 AM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
> 
> As mentioned elsewhere, SWR is also a consideration. Some relays will be rated for X watts at 1.00001:1 SWR, others will be rated for X watts at 2:1 SWR. Without the full data sheet on the relays and data at your frequency of use, it’s a guess. 
> 
> Bob
> 
> 
>> On Oct 16, 2014, at 11:12 PM, W2HX <w2hx at w2hx.com> wrote:
>> 
>> Hello all,
>> 
>> I am looking to switch full legal limit coax feed to 3 antennas remotely. I am looking at some surplus coax relays to do this. One that I am looking at uses "N" connectors and the spec sheet says it is rated for "300W cw @ 3000 MHz & Sea Level).  Well, I am not too far from near sea level, but my question is, can anyone hazard a guess about how the power rating might change from 3 GHz to 30 MHz? I know that UHF/PL-259 are better connectors for higher power than "N." There is no information on power rating vs frequency on the data sheet (this is a Transco product).
>> 
>> thanks
>> 
>> 73 Eugene W2HX
>> 
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