Topband: K9ay loop not performing

[N4ZR]

Thanks everyone who responded - I think I know enough to proceed.

I had wondered about the need to open the shield side of the coax - I 
have 16 turns of RG-400 on a Type 31 core right at the base of the 
inverted L.  If the darned rain/snow ever stops, I think I'll 
temporarily re-connect the shield and compare, but my expectation is 
that a single pole will do the trick.

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 12/10/2019 1:54 PM, Guy Olinger K2AV wrote:
> The need to disconnect the feedline shield is to block common mode signals.
> A K9AY approved **EXCELLENT** common mode block (not a regular "balun" with
> likely awful blocking on 160m), or (GASP) an isolation transformer will
> take care.
>
> In the case quoted, with the coax center contductor opened, the
> stinky-on-160-blocking "balun" is how the noise gets in. Further since Pete
> saw a 4 S unit drop by simply disconnecting the TX wire, it's likely that
> his common-mode provision, even if not intended as such, would appear to be
> satisfactory, and therefore a double pole relay (lot more expensive) is not
> called for.
>
> 73, Guy K2AV
>
>
> On Sun, Dec 8, 2019 at 7:30 AM Rob Atkinson <ranchorobbo at gmail.com> wrote:
>
>> If you open the tx antenna feedline for rx, from my experience, you
>> need to completely open the entire feedline, namely the coaxial cable
>> shield as well as the center conductor.   coaxial relays that maintain
>> conductivity of the shield when N.O. won't detune/isolate the tx
>> antenna.  I use a pair of open frame relays for this.  Fortunately on
>> 1800 kc the Z bump is almost nonexistent.   What will govern your
>> choice of relay is tx power and tx time, and whether or not you
>> require QSK.  I do not, but if you do, you may have to consider
>> something like multiple paralleled reed relays tor speed and power, or
>> vacuum relays.
>>
>>
>> 73
>> Rob
>> K5UJ
>> _________________
>> Searchable Archives: http://www.contesting.com/_topband - Topband
>> Reflector
>>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
>