Hi Antonio, I have a rough, untried paper design.? " bands is
probably OK, as you can assign one band to vfoA, and the other to
vfoB, otherwise you are in for a LOT of knob twiddling, or a
factory reset when you change bands. I have settled on 2 adjacent
bands, covering less than an octive. Say 30 and 40m or20 and 17m.?
This allows you to use a low pass filter configured for the higher
frequency.? I will make the capacitive trimmer a front panel
control, and call it a preselector.? It should cover 2 adjacent
bands. If you want to change the coils on each band, I would
re-configure the rf input tuned circuit as a 2 torroid pair, and
just change one of the torroids for each band,? The fixed torroid
would be wound with say 10 tri-filiar turns. 2 of the windings are
arranged as a push-pull input to the mixer. The 3rd winding
connects to 10 turns on the 2nd core that is to be switched. Th e
2nd core also has a resonant winding on it, for the band in
question. This eases the switching a little.? this is just a paper
excersise, it will be a while before I get around to doing
something about it.? It would be nice if Hans modified the
software to allow larger ncremental tuning; in addition to the
10,50,100 Hz /step, we add MHz or 100KHz steps.
73
Alvey
On 04/12/17 15:28, Antonio Fernandez
wrote:
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Hi group,
While I wait for the shipment and delivery my QCX
I was wondering if someone has considered or experimented with
a dual band (adjacent bands, e.g. 20 and 17m) version of the
QCX.
I wonder if compromises could be made on the LP
and the passband tuning filters to accommodate the 2 bands (20
and 17m). ?For the class E amp two h/w switchable L4 coils
could do the trick.
Has anyone done experiments along these
approaches?
Cheers,
Antonio, ea4le/kc2hax
