20 metre transmitter kit suitable for data


Cormac Gebruers:

I'm getting stuck into a new project that will involve a 20 or 40 metre QRP transmitter (a few watts is sufficient) capable of transmitting DominoEX.
I do a fair bit of construction but I haven't gone down the homebrew transmitter route before so the space is entirely unknown to me; I'd appreciate a steer from anyone to either a good transmitter design or (even better) a suitable kit.

Thanks in advance
Cormac, EI4HQ
[Cobh, IO51uu / UTC+1] NNNN++++

Dale Hunt:
I'm not familiar with the modulation type of Domino, but unless it is a keyed carrier mode
such as Hellschriber then it will require a linear transmitter chain.  If it is designed to be
fed into the mic circuit of a rig, then any transmitter designed for SSB should be adequate
for the purpose.  (The main issue will be VFO stability.)

Cormac Gebruers:
Noted with thanks - it is as you describe so I'll add VFO stability and linear requirements to the list...

Dale Hunt:
If you are only operating over a narrow frequency range, using a crystal oscillator in place
of a VFO may be adequate.  (Some digital modes are much more critical for frequency
stability than others.)

The BITX design may be a good starting point.

I'm not that familiar with the kit offerings currently available, but here are a few
designs to consider.  Just about any SSB transmitter strip using a CB output transistor
is probably going to work, then question then becomes the VFO/XTAL oscillator.


Dale Hunt:
And here is another link - there are a number of circuits of interest in both the 40m
and 20m sections;



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