[Elecraft] XV144 transverter firmware

[Edward R Cole]

Pierre-Francois, F5BQP:

Substituting the xtal LO with a PLL will solve the frequency drift 
issue.  One caveat is making sure the PLL has low phase-noise as that 
affects ability to handle strong adjacent frequency signals when 
trying to copy weak signals (which is why you are using JT65).  One 
of the shining parameters of the K3 design.

I had DEMI transverters long before I acquired my K3/10 (and KX3) so 
have continued to use them.  I have heated xtal osc on 144 and 222 
but use a PLL on 432, 1296, and 3400 MHz.  Recent re-design by DEMI 
has improved xtal LO frequency stability while the xtal oscillator 
has excellent phase-noise performance.  I see about 7 to 10 Hz drift 
on the 101 to 194 MHz xtal oscillators in the new L-series of DEMI 
transverters.  But LO's for higher bands multiply the xtal oscillator 
frequency which also multiplies drift.

For 432 and higher I found using the N5AC ApolLO PLL's worked well in 
DEMI transverters.  The N5AC Apol series is not the lowest in 
phase-noise so that could be a real concern for those doing VHF-plus 
in high density RF environments.  So  one should consider phase-noise 
when deciding on a PLL.  W1GHZ has a new VCXO design that exhibits 
lower noise than a PLL. Of course this is for the experimenter ham who DIY.

I do think there will be a increasing use of PLL in VHF and higher 
equipment due to demands of digital modes and need for better 
frequency stability on the higher bands.

One issue is the need for an external 10-MHz reference.  That is not 
hard to embed into current equipment.  I did that for a 432-MHz 
transverter customer.

73, Ed - KL7UW
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