Tom Childers, N5GE wrote:
>
> This beat note experience is one of the reasons I got a K3. My Orion II
> always
> had a 6Hz difference between the A VFO and B VFO. It was very irritating
> after
> having Kenwoods and Yaesus that did not suffer from that problem.
>
> I am still waiting for my KRX3, but when I heard about the offset
> possibility I
> changed my order for the KRX3 from a 2.7 KHz filter to a 2.8Khz filter
> (the
> others ordered are all 8 pole filters) and replaced the 2.7Khz filter in
> the K3
> with a 2.8Khz filter.
>
I experienced the same problem with my Orion but it had a constant 2.3 Hz
offset.
It's absolutely unnecessary to use only 8-pole filters in the K3 for
diversity. In the case previously cited here by Doug N6TQS, his 2.7k
offsets were only off by 10 Hz so it would not cause any problem to set both
to the same offset (i.e. 10 Hz out of 2700 Hz is 0.4% and not significant).
Don't be deceived in thinking 8-pole filters actually have zero Hz
offsets...they don't! Several others (W0YK for one) have reported narrow CW
8-pole filters with offsets of 40-80 Hz. In a "250 Hz" (actually 370 Hz)
8-pole CW filter, this can be significant (i.e. 80 Hz out of 370 Hz is
~20%). Also, if you go through the process to zero them, there is no
guarantee that any two 8-pole CW filters will actually have the same offset.
When I ordered my new K3 with KRX3, I did not order matched 2.7k and 500 Hz
filters, thinking that the 2.7ks would not be far enough off to be
significant and hoping the 500s would be about the same since they would
probably come from the same manufacturing batch. The 2.7ks were off by 30
Hz so I split the difference and set both offsets to a number between, as
Lyle suggested. The 500s just happened to be identical. If they had been
off significantly (e.g. 50 Hz), I might have returned one and asked for a
matched filter at the additional $30 cost.
My KRX3 works perfectly in diversity with no beat using only 5-pole filters.
73, Bill
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