I have rebuilt / changed mounting and wire routing several times seems to have greater effect than anything else. filter, shielding etc like the old days of computers caps everywhere lol. just my observation.
On Apr 14, 2017 2:13 PM, "electronic design via Groups.Io" <electronicdesign=
[email protected]> wrote:
Hi Allard,
thank you for your time and info's. Now everything is clear. I also suspected VFO frequency being on the low side of IF.?
Thank's again! Happy Easter!
73! Adi
YO2LIW
On Friday, April 14, 2017 11:28 PM, Allard PE1NWL <pe1nwl@...> wrote:
Adi,
I watched your video and compared to my own BITX.
With 2mA drive strength (and antenna disconnected) I have similar results as you have: 1 extremely strong birdie at 7199 kHz and a few faint ones at lower frequencies. The tuning clicks are increasing as I tune towards the 7199 birdie (same as in your video).
When I increase the drive level to 4mA, the birdie at 7199 is almost disappeared. There seems to be very little effect on the faint birdies at lower frequencies, but I find them broadly acceptable. Also the tuning clicks do not increase anymore in certain band areas.
Further increasing the drive level to 6mA or 8mA does not make any difference in my case.
So playing with the drive level only seems to affect the birdie at 7199. The other, much weaker, birdies are not affected.
When I connect the antenna I often receive several strong images from SW broadcast stations. Playing with the drive level doesn't have any effect on them. The images are resulting from the basic concept of this rig (VFO frequency at the low side of the IF). You need to move the VFO frequency to the high side of the IF to get rid of them. But then you must also shift the BFO frequency by about 3kHz to the other side band. I tried it, it works. No images whatsoever!
73, Allard PE1NWL
lee hyde