the 1 Khz drift is more of a construction problem that a design problem.
I would suggest that you try the following:
1. make all the components connect to each other with short leads and without any 'jiggly' wires.
2. put an epoxy glue over the coil and stick the coil to the board with a drop of expoy.
3. put a sheild around the vfo (i know it is too much work).
4. Are u connecting to the tuning capacitor with flexible wire? use a short stiff copper wire or a resistor tail end.The ground end should be directly in contact with the chassis.
5. Make sure that your regulator is actually regulating. Check the diode (i have often mistakend 1N4148s for other zeners).
Unfortunately, an open VFO on a work-bench is rarely stable. Especially, if your coil has an low permeability like the tap washers.
- farhan
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On Thu, 3 Feb 2005, pa2rf wrote:
Thanks for advice dear Chris,
Saw on the forum that the BITX17 already seems to exist!
OK, past couple of days I started to setup the power supply unit
capable of delivering the required voltages.
Also did some trials with a VFO working from 8.060 - 8.180 MHz. (+ 10
MHz IF will give the proper range) Frequency range seems to be ok but
stability is bad. After 20 minutes waiting freq shift of 1 KHz still
exists. I think I will order some components for a HuffAndPuff
circuit for stabilizing purposes.
Or maybe a FET Hartley oscillator. We'll see.
Bye for now and till next time.
Dank voor je reactie Chris. Leuk om te zien dat andere om druk met de
bitx in de weer zijn.
73 de Ron
pa2rf
--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:
Dear Ron,
splended idea to make it for 17 mtrs.
In your message you asked for suggestions, you want to have more
suggestions then all the postings in this newsgroup, including
Photos, Files etc?
Can you be more precisely what else you need?
By the way, you can show your progress in this newsgroup, you do
not
need an other website for it.
Best regards,
Chris.
Dear bitx20 homebrewers,
I intend to build the BITX for the 17m WARC band (18.068-18.168
MHz). My ultimate goal will be to work psk31 with this splendid
rig.
Has anyone suggestions to convert bitx20 to bitx17. VFO must be
changed of course and RF filters... I intend to keep my progress
updated on my website (see below).
73 de Ron
PA2RF
pa2rf@y...
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