Kevin,
There is one possibility that your 51 ohm load (measured at DC) is not a
good 51 ohm pure resistance at the frequency you were measuring. Borrow
an antenna analyzer and test your load at the frequency of operation.
If that load does measure as a 51 ohm pure resistance (X value equals
zero or very low), then you have a KAT2 problem, but if it is not a pure
resistance, then your results will be misleading because the generator
was not looking into its output impedance and the voltages and currents
being fed into the K2 will be not as expected.
That does not say that your KAT2 is not causing a problem, it *only*
says your test results may be inconclusive.
73,
Don W3FPR
On 7/10/2013 9:41 PM, Kevin Cozens wrote:
Greetings, all.
For some time I've suspected my K2 of being partially deaf (ie. not as
sensitive as it should be). I bought an XG3 a while ago and finally
sat down to check my K2.
I set up the K2 following the XG3 manual. Volume control set to was
slightly before 12 o'clock so I had maximum volume possible before
there was audible distortion heard in the speaker, I used a 400Hz
filter as I don't have a 500Hz one set up, and I removed the KAT2. I
took measurements at the speaker terminals with the speaker disconnect
as the volume was quite loud with the speaker connected. On 40m, S+N
was 532mV and N was 19.2mV for a receive sensitivity of -135.7dBm
(approximately).
I installed the KAT2, tuned in to a dummy load on ANT1 that measured
51ohms on an ohmmeter, and set the KAT2 to calS mode. I ran the test
again without changing any controls from the first test. The speaker
volume was only 55mV, about 1/10th what it was without the KAT2.
Calculated senstivity was around -128dBm.
Sensitivity seems a bit lower with the KAT2. Perhaps I should have
upped the volume setting but I thought I should try and do a more
direct comparison to the bare K2.
Center conductor of ANT1 to KAT2 output is only 1 ohm so there is
nothing obviously wrong at DC levels. I don't like the 10 fold drop in
speaker volume with the KAT2 installed with all other things being
equal. Is this considered "normal" or is this an indication of a
problem in my KAT2? Any thoughts what to look for if this 10 fold drop
in output is not normal?
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