Dear Ashhar,
It is an honour to me? to chat to the designer of the bitx ! Compliments for the extensive info on the internet. I like the KISS (keep it simple stupid) principle a lot. I appreciate all your good advice.
I have made some notes behind each of your hint&tip:
. make all the components connect to each other with short leads and without any 'jiggly' wires.
--That's what i did
2. put an epoxy glue over the coil and stick the coil to the board with a drop of expoy.
-- here i can made an improvement ! Now the fixed value coil floats above the pcb
3. put a sheild around the vfo (i know it is too much work).
--message understood. Yes shielding?improve the situation?
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.
--yes i used a short thick copper wire to the capacitor's hot end. The ground end is directly soldered onto the pcb
5. Make sure that your regulator is actually regulating. Check the diode (i have often mistakend 1N4148s for other zeners).
--yes it is a stable voltage is measured after the zener.
?
I have used ceramic capacitors and will replace them the the polysterne ones for better performance.
What is your opinion about working with digimodes (like rtty and psk31) with the bitx, Ashhar? Is there any experience in this field ? A 10 Hz stability requirement for psk31 is very though!! (altough i managed to get an old kenwood ts515 with tubes working on psk31..)
Ron
pa2rf
http://home.versatel.nl/laar60
Ashhar Farhan wrote:
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
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" 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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