K9AY Antenna - Remotely Variable Termination

Clifford Buttschardt cbuttsch@slonet.org
Wed, 27 Jan 1999 11:48:55 -0800 (PST)

Good comments.  I just built a variable termination for another fellow who
has the K9AY already performing.  I used an old fashioned RAYSISTOR,
something the Raytheon sold many years ago.  A homemade termination was
also built using a grain of wheat bulb coupled to a Radio Shack CdS cell
with a drop of clear salad oil!  This worked even better as the ON
resistance was much lower.  Both devices were shunted with a 1500 ohm
resistor which produces a high resistance limit.  In the latter case, the
variable termination is to be used with a Flag or Pennant antenna on 160
meters.  Incandescent lamps appear better as they do not produce RF noise.
Cliff Buttschardt  K7RR/W6HDO

On Wed, 27 Jan 1999, tracey gardner wrote:

> Hi All
> Further to my last message on the K9AY, which Andre' kindly put
> out for me.
> I forgot to mention that I am using a remotely variable termination,
> similar to Steve Byan's unit, on my K9AY.
> However I subscribe to the KISS principle and the variable
> termination that I'm using consists of a discrete LDR and LED 
> combination in a bit of plastic tubing and not the Vactrol which
> isn't available over here.
> The remotely variable termination makes all the difference to the
> K9AY as you can optimise the null on the offending station.
> 73s Tracey G5VU