Both on my version and G6ALB's version the measured RF power out was in excess of 200mW, which is around 2-3dB more than I had crudely measured. The RX sensitivity on both was such that below -100dBm (around 2uV) was audible in our earpieces in a quiet room. Backwave carrier on TX was rather too high at around -10dBm. Second harmonic was also only around -6dB, so a low pass filter is really a necessity apart from casual short tests.
It does seem that the simple design is reproducible and its performance not at all bad for something this simple. The only major shortcoming is the chirp.
3 comments:
Hello Roger
For a two transistor rig the sensitivity is excellent.
I am thinking of some circuit ideas based around chirpy.
Thanks again for a simple design.
73's Tony
A T-50-6 should do here as well as T37-6 ??
What do you think Roger??
Tony B
Tony B
You can google the online calculator for the T37-6 work out the inductance from the number of turns and then recalculate it for the T50-6. and keep the tapping ratio the same. This should work just fine.
I have just wound 20 turns of 26SWG enameled wire on a 1 inch nylon washer that dips with a GDO and 50pF variable cap at 30 MHz the circuit loading should bring it
down to 28 MHz .
All best with your chirpy.
Tony
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