[Elecraft] 472KHz/500KHz

[Edward R Cole]

There is another caveat to keep in mind when using the K3 in
transverter mode.  Sensitivity will be subject to the ham band
BPFs, so a preamp may be needed if the "IF" freq. falls well
outside the BPF passband unless a general coverage module (KBPF3)
is installed.  The KBPF3 works fine if the KXV3 is in TEST mode
but the K3 is not setup with a transverter band, ie. you're
parked on 10.500 MHz for 500 kHz conversion.  However, when using
a transverter band (ie. direct freq. readout using IF=10, RF=0),
the KBPF3 is not switched in when it should be.  I have brought
this to the attention of support/development since it is clearly
a bug and there should be no need for a preamp with the KBPF3
installed.  In the meantime, I use IF=14 and RF=0 for a
transverter band and get direct freq. readout.  The 20M ham BPF
is wide enough that there isn't a significant amount of
attenuation at 14.500 MHz.

Having both 3.5 MHz and 10 MHz would be good additions to the
transverter IF selections.  The former because there are numerous
converter circuits published or were/are commercially available
based on 3.5 MHz, the latter because it is a defacto reference freq.

73 - Eric NO3M (WD2XSH/46 - ARRL 600M Experimental Group)
----------
Eric,

Thanks for reminding that a KBPF3 is needed for general frequency use 
in TEST mode.  I chose to install one when I bought my K3/10 because 
I was going to operate on 500-KHz with my K3.  It is not operating in 
transverter mode but in TEST mode as RF output is at the transverter 
output RF jack and not at ANT.  So there is no need to use 
transverter mode.  Frequency would read 10.472 when on 472-KHz.  I 
think that much easier than having to build a stable xtal LO on 
either 3.5 or 7.0 MHz.  I bought my OCXO on e-bay for $42 and drifts 
about 1-Hz every 4-6 months.  But that is just my opinion.

73, Ed
My prototype transverter uses a SBL-1 mixer from mini-circuits and a 
2N3906 buffer amp into a three-pole filter.  That has enough RF to 
drive my 500-KHz linear amp.  Others will need to come up with 
linear's to provide at least 25w to take advantage of the expected 1 
ERP limitation on 630m.  With my antenna efficiency 100w => 4.15w ERP 
on 500-KHz.