On 04/01/2017 10:11 PM, Robert Toegel wrote:
With idea of a VFO that can do 3 - 7 and 7 - 20, how about making aI've done that. It works well fi the VFO is stable as the drift
really stable VFO at the 3 - 6 range and switch in a doubler circuit
for the higher range? Don't know if that would be good enough but
it's just a thought.
I've built VFOs with a temperature compensation circuit that workedThe differential cap makes it much easier.
well if you adjusted it carefully. Really nothing more than a high
negative coefficient cap and a high positive coefficient cap fed to a
differential capacitor in the tank circuit. Tune for minimum drift.
Used to test it using "Circuit Freeze" when that was available.
I also have a couple of Atlas rigs too and they (mine) wereNot all were. The bones are good.
On Sat, Apr 1, 2017 at 6:50 PM allison <ajp166@xxxxxxxxxxx
Lately I have been playing with Atlas 210X traceivers and they use
switched frequency VFOs
with the 10M range going to 23mhz. With good temperature
compensation they are
amazingly stable. Granted many made it from the factory with poor
but I have two that will hold within 100hz an hour after 10
minutes at room temperature.
*From:* Ashhar Farhan
*Sent:* Friday, March 31, 2017 11:24 AM
*Subject:* [minima] Re: Finally getting around to building my
A simpler scheme than the Si570 is to use a lower frequency IF
like 11 MHz.
Make a solid JFET VFO in a shielded box that has two sections,
one that goes from 3 MHz to 7 MHz, the other that goes from 7
MHz to 20 MHz. Then, just add a very simple Huff and Puff.
This scheme may look basic, it is not. The phase noise of such a
system will beat the best of the radios on the market.
It is not exactly easy either. First, you need a very nice
tuning capacitor with slow motion drive. Next, you will need
good mechanical skills to build the VFO.