Comments are moderated before they will appear on the website, this is a manual process and may take some time. Please be patient.
Author Name is a required field.
Email Address is optional, but without one I won't be able to contact you back. It is never shown or linked on the website. You can always just email me if you'd rather not post a public comment. I generally reply in-line with a comment rather than email you back, unless I want to discuss something in private or off topic. Please check back to see when I reply.
Website URL is optional, if supplied the Author Name will be hyperlinked to this URL.
You may use wikitext in the body, preview may be handy here. Don't worry if you can't figure them out, just give me a hint what you want linked to what and I'll do it during moderation. Wikitext is not BBcode!
Spammers: Please don't bother wasting your time scripting up posts to this form. Everything is moderated, your post will never be seen on the web even transiently, there is no way to even view it by its internal ID, it will never be indexed. I will simply delete your post in the moderation interface. If I'm your target audience you're really on the wrong track; I'll never click on a URL in your garbage. The post content is not emailed to me (and I don't use a Win32 mail client anyway), I view the posts in plain text in the moderation interface so no clever tricks of any kind will make anything you type be interpreted by anything other than me, a human. Just give up and go elsewhere please!
17th December 2011 17:22
Mike,
Glad you got it working OK mate. :)
Regards,
Alan
15th December 2011 23:14
Just a note to say thanks for posting this little receiver and your help Alan. I had great fun making this and its performance is surprising.
cheers
mb
25th November 2011 12:13
Many thanks for the coil winding clarification. The oscillator is working fine and I have now wound the ferrite ring coil.
cheers
mb
12th November 2011 23:25
Mike,
Yes, all three windings are the same number of turns. The winding is trifilar, you twist three wires together first, then wind them as one on the core. Separate them afterwards using a meter. The dot shows the phase, pick an end all three wires from that end are the one with the dot.
Regards,
Alan
12th November 2011 00:11
Alan,
Thanks for posting this - I will give it a try. I new to this stuff ... are all the windings 6 turns on the mixer ferrite ring?
thanks
mike
3rd July 2011 18:13
David,
I just dug it out and counted the turns; 92.
Regards,
Alan
18th May 2011 18:19
What values did you use to get the pto to tune 3.4 to 4.00 mhz?? how many turns on the coil?? would like mine to cover the complete 80 meter band but doesnt right now.thanks alot
10th July 2008 19:27
Erik,
I don't think the PTO will be stable enough on 20 metres, however you could try it. You could also try running the PTO at a lower frequency and multiplying it up (but this will also multiply up its instabilities), or mix it with a xtal oscillator to generate the LO.
The later is probably your best bet, say with the PTO at 4-5 MHz and the xtal higher. Add a BPF to reject the other products and isolate only the one you want. An alternative might be a sub-harmonic mixer like the Poliakov design which needs an LO at half the RF frequency, a PTO at 7 MHz is fairly stable if well built.
The rest of the circuit should work fine on 20 metres by just changing the filtering but the front-end amplifier might be improved and as the band noise is lower on 20 metres it could be worth it. If I was building this radio again I'd use a double-tuned LC filter in the front-end and probably Sallen-Key filtering in the audio amplifier.
Regards,
Alan
9th July 2008 22:57
Hello Alan,
Ik admire the KISS approach in your projects. No difficult parts standing in the way of construction. That's very attractive to the would-be homebuilder like me.
I would like to build a decent 20m band direct conversion receiver. Can the 80m scheme be ported to 20m? Will the PTO be stable enough?
Thanks for any helpful suggestions!
Erik
ON4ADV
6th December 2012 21:46
Mario IZ0IRH wrote...