[Elecraft] Ameco PT-3

[Tom W8JI]

> When the antenna is connected and disconnected the noise floor moves just 
> barely.  You can tell, but it requires a critical ear.

That is too little. That is about how my K3 behaves on six meters on SSB 
bandwidth! On the narrowest bandwidth you use, you should hear a very well 
defined noise increase, several dB, going from a dummy load to the antenna.

>>A note about my antenna.  It is a HyGain 5BDQ trap dipole and the SWR on 
>>it is 1.2:1 into about 200' of LMR240.

Since feedline loss and SWR in receiving is set by the receiver, SWR in the 
feedline on receive has nothing to do with transmit VSWR (where the antenna 
is the load). I've never measured the input impedance of the K2, but it 
could be you have an impedance mismatch between the K2 receiver and the 
feedline, which would result in feedline losses aggravating the feedline 
loss problem.

What the 1.2:1 SWR indicates is the antenna mismatch is around 1.4:1 and 
feedline loss on transmitting is about 2.5 dB.

I have no idea what the K2 looks like for SWR on receiving, but many 
receivers I've measured are pretty far off 1:1 SWR. If the K2 looks like a 
2.5:1 SWR (which is a reasonable upper limit based on other receivers I have 
tested), feedline loss would be 3 dB plus you would have an additional .12 
dB mismatch loss at the antenna (the source).

Sounds to me like the K2 you have needs more sensitivity if a dipole with 4 
dB or less system loss won't firmly set noise floor.

73 Tom