Looks like you have interchanged the ground and antenna wires!
Black is ground everywhere in BITX40. Brown is the center pin of BNC or
SO239.
Let us know!
Good luck
Raj
At 07/07/2017, you wrote:
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Hi all,
I moved my Bitx40 board to a smaller enclosure and somewhere along the
line I ended up with massive breakthrough from AM stations.
This happened even with the VFO unplugged from the board.
The breakthrough stopped (surprisingly) when I grounded the centre
contact of the antenna input. 7mhz? SSB signals came through
fine!
I experimented with a couple of capacitors across the antenna input
instead of the grounding, and finally used a 100pf capacitor.
Now the receive is great, no AM breakthrough at all and a reduction in
noise. Signals still getting through fine.
Transmit seems ok (on a nearby receiver), but I haven?€?t tested power
output.
I?€?m not sure how that all worked. I have Peter parker?€?s improved
audio transmit mod. Also removed the 1uf capacitor between pins 1 and 8
of the LM386
and replaced with resistor/capacitor.
Any thoughts?
John
VK2VOL
Raj vu2zap