[Elecraft] New P3 TX Monitor....unusual behavior with SWR (at times)

[Randy Farmer]

Having the LP-100A on the antenna side is by design. I'm not much 
interested in monitoring the antenna VSWR in real time, but I do want to 
know the power being delivered at the tail end of the station RF lineup. 
The "light show" on the KAT500 and the KPA500 (if it's being used) as 
well as the internal indication in the K3 gives plenty of redundant 
information about whether or not the antenna tuner is doing its job. The 
unique vector measurement capability of the LPA-100A also makes it good 
for maintenance checks. I periodically run the utility program to have 
the LPA-100A measure the various antennas across their operational bands 
and compare the results against historical data. This lets me see any 
changes that might have occurred -- these changes would be masked by an 
antenna tuner between the LPA-100A sensor and the actual antenna.

I actually use the KAT500 almost exclusively for tuning my 80 meter 
inverted L, which is too long electrically but mechanically impossible 
to tune properly. Although all my other antennas are resonant on their 
respective operating bands I also leave the KAT500 on line to use as a 
"line flattener" on 160 and 40 meters if I should operate outside of the 
normal CW bands these antennas are tuned for.

73...
Randy, W8FN

On 8/13/2015 12:30 AM, Phil Hystad wrote:
> Randy,
>
> If your LP100A is on the antenna side of your KAT500 then you are putting your LP100A in the region of higher SWR if your antenna is not close to resonance.  I think you would want to put your LP100A in the inboard side of the KAT500 so that you are properly showing the “tuned” SWR on the LPA100A and your readings will be more accurate I believe.
>
> If you want to know the antenna side of the SWR, what the KAT500 refers to as the Bypass SWR since it is the SWR you see if you bypass the KAT500, then you can use the KAT500 utility program to display that.
>
> I am not seeing the problems you describe.  For example, when I run without the TX Mon Sensor in place, there are absolutely no SWR problems at all (look again at the configuration below that I have).  I should also note that today I did not see any problems with the SWR spurts I originally reported even with the TX Monitor sensor inline.
>
> 73, phil, K7PEH