Re: Qrp-labs and a Huff and Puff circuit board
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Mike
Several years ago when I was experimenting with H&P designs I found that a Vackar
VFO was better for my H&P uses.? In addition to being stable, the output is low impedance
and seems relatively immune to changes in loading.? But of course each person will
have his/her own preference of oscillator designs.?
The edge detection part of H&P seems to work better if compared signals are square,
or nearly so.? This works well with tube type oscillators because they have higher
voltages that can be made almost square with simple diode limiters at lower voltage
levels.
Arv _._
On Tue, Apr 9, 2019 at 1:53 PM Mike Donovan < mdon01@...> wrote: One more issue with the Heathkit vfo/DX-60b problem is that the vfo outputs 7 mhz for 40-10 meters.? The radio x2 x3 or x4 to get the correct frequency.....so, a 100 hz drift on 40 meters becomes a 400hz drift over the same time period on 10 meters.
The HG-10 can be more stable than it was designed by completely rebuilding the vfo (re: temperature stable caps, removing heat, etc) but an accurate Huff and Puff implementation would fix it completely, once set up properly.
I am starting on a homebuild PTO vfo using a kit from qrpguys, that I hope to use as a test bed for making a stable 5mhz PTO for an a.m. transmitter build.? I might just throw my hands up in the air, in the end, but I would like to see what I can do.
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