[Elecraft] Re: Question re K3 diversity reception

[Ed Gray W0SD]

Wayne,

What about Snow static on the main antenna and danger to the rcv?  It is 
fairly high voltage and I assume not much current? I had a bunch during 
the 10 meter contest.  Those of us in the north country hear it snapping 
in the antenna switch quite regularly if not grounded during the winter 
time.  I have never had trouble with previous radios but wondered since 
I have read comments about induced power from a passing thunder storm so 
in these cases you should unhook the K3.

Ed W0SD



wayne burdick wrote:
> Jerry Flanders wrote:
> 
>> At what approx. RF voltage level sent back into the rx from the second 
>> antenna do we need to worry about additional protection like external 
>> switching or shorting?
> 
> The short answer is: the voltage resulting from input power high enough 
> to trigger the COR (probably 0.5 to 2 W in most cases). This will vary 
> widely because the impedance of the sub's antenna on the *transmit* band 
> may be totally different from its Z on the sub's receive band. At very 
> high impedances, strays from the coax and the COR circuitry itself come 
> into play. If you use the KAT3's non-TX antenna as the sub's AUX source, 
> the small amount of leakage between ANT1 and ANT2 can also affect the 
> COR trigger level; this will depend on the load Z and will vary from 
> band to band.
> 
>> Also, what do I hear when the COR activates? What sound? Is this a 
>> reed relay?
> 
> You'll hear about the same thing you hear when you switch from CW to SSB 
> mode (this throws a relay on the KREF3 module), except it will follow 
> the keying. It's not a reed relay, but it is small, and rated for very 
> long mechanical life. Still, I recommend not pushing it. If you hear it, 
> you should improve the antenna isolation on that band.
> 
>> I operate SO2R and occasionally need to measure to verify safe RF 
>> level into the second rig and would also like use my 2nd K3 
>> (synch-tuned) for diversity rx while tx'ing on 1st K3. An actual RF 
>> voltage level I can use as a measurable limit would be a very useful 
>> parameter.
> 
> What I mentioned above is the best I can give you. If you can keep it to 
> 10 Vpp or less, I think you'll be OK, but I'd still advise testing 
> things before you operate in a contest.
> 
> 73,
> Wayne
> N6KR
> 
> ---
> 
> http://www.elecraft.com
> 
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> 
> 
> ------------------------------------------------------------------------
> 
> 
> No virus found in this incoming message.
> Checked by AVG - http://www.avg.com 
> Version: 8.0.176 / Virus Database: 270.9.18/1851 - Release Date: 12/16/2008 8:53 AM
>