Re: QR2S - Osc freq too high
- I'm having a difficult time pulling the oscillator down to 10.140 Mhz. With variable cap 138 set at maximum C, I added some additional capacitors. Here are my results:
0 pf 10,140,435 Hz
10pf 10,140,408 Hz
37pf 10,140,345 Hz
"Frequency" setting is at 0
--- In GenesisRadio@yahoogroups.com, "Nick" <nick@...> wrote:
> Very good - you are (alomst) spot on.
> If you have installed fix value cap in place of C138 then replace it with
> trimmer (this is the third, spare trimmer
> whic was included for that purpose).
> Alternatively just add 5-8pF in parallel to C138.
> Happy QRSSing!
> 73 Nick VK1AA
> >Here are the frequencies I see with C138 set for lowest frequency. These
> >are accurate to well under 1 Hz.
> Setting Measured (hz)
> 0 10,140,436.16
> 10 10,140,447.88
> 50 10,140,502.62
> 100 10,140,628.24
> 128 10,140,700.93
> 200 10,140,879.27
> 255 10,141,014.95
> I think I would like the lowest frequency at or below 10.140 Mhz.
> Oven Temperature set at 45.
> Measured temperature of Q12 using simple thermistor digital thermometer:
> 42.7 degC