Re: Ideas for AM, NB FM Demod and CW filter board

ajparent1/kb1gmx
 

if the board does 10W SSB then am will be about 2.5W, not so much on that.
The bands I see AM on or are 160, 75 and 40M and rarely on 10M but 2.5w
will not cut it.  Generating  AM in a SSB system requires doing low level
AM adding parts.

For FM you need to cut back on power as it 100% duty cycle.  The only place I see any 
HF FM activity is 10M, the rest is VHF and up.  That and a way to modulate one of
the oscillators.  

Adding AM and FM to a ubitx is a bad way to go.  For AM RX you could use a chip but
then you need agc. Listening to AM without AGC is really poor.   Some AM/FM RX chips
exist but they must be upstream of the 12mhz filter (too narrow for both am and
FM as you need a 6-8khz wide filter for that.

The uBitx is well developed for SSB and CW why make for costly and complex for modes
not often used and might make for a better separate low cost radio. 

Now using it with a transverter to get SSB on VHF and UHF is simple and a good match.
For FM work on those bands (2m and UHF) there are so many cheap radios that do that
well enough so don't bother.  Here a BaoFeng is under 30$ and does everything I can
want at 5W and it fits in my bag.

Can it be done, yes the FT817 and IC703 prove it can.  Inexpensively not so much.
I'd expect doing that would turn the board form a 110$ to a 200++ very quickly.
Also with used FT817s out there for about 400$ (they do 6,2 and 432 as well)
as all mode cost and compliance with regulator agencies becomes an issue.


Allison

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