[CQ-Contest] 10/15 interaction

Joe nss at mwt.net
Thu Nov 6 12:15:40 EST 2014

How about using one of these?

Then you are good on any band too?

The Original Rolling Ball Clock
Idle Tyme
On 11/6/2014 9:18 AM, Randall K Martin wrote:
> Over the years, I've managed to clean up most of the cross band 
> interference that occurs when I operate my SO2R station running high 
> power. The one exception is that I cannot use my 10M monobander to 
> transmit while receiving on my 15M monobander. This is not surprising, 
> since they are only separated vertically by about 8 feet. Transmitting 
> on 10M must be dumping significant power back into the 15M transmitter 
> (an elecraft K-3) since it causes the COR relays to click and I get 
> the "HI RFI" error. When this happens, I immediately stop transmitting 
> and flip the 15M rig over to a tribander on a second tower. Normally, 
> I'm able to remember not to do this, but in the heat of a contest, I 
> forget. What I find odd is that I can transmit on the 15M monobander 
> while the second radio is connected to the 10M monobander and there is 
> no "HI RFI" problem. In fact, very little interference.
> Here's my question. I'm contemplating purchasing a high power band 
> pass filter (4O3A) to prevent the interaction. I'd prefer not to buy 
> both a 10M and a 15M filter if I don't have to. My intuition tells me 
> that I should be able to add the filter to the 10M transmitter. Any 
> thoughts on this? Is there some other path in which the RF could be 
> reaching the 15M rig that would render the band pass filters ineffective?
> I have dunestar 100W band pass filters on both rigs, placed between 
> the rig and the amp. I know that adding separation between the 
> monobanders would help, but my tower configuration isn't really 
> amenable to adding more separation.
> 73
> Randy K0EU
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