At last, I have radio silence ... oh joy. And it is not very difficult to achieve, either.
Problem one:
I had a cheap Chinese dc converter on the PAW, which was hugely noisy. Bad move.
Squelch on setting 14 (max)
Solution one:
I fitted an Anker dc converter instead. Much better.
Squelch on setting 10
Problem two:
I had a cheap Chinese dc converter on the radio, which was hugely noisy. Bad move.
Squelch on setting 10
Solution two:
I fitted the dc converter that came with the radio - which was a bit better.
But then I fitted a voltage regulator instead of a dc converter - much better.
Squelch on setting 6.
Problem three:
Some interference was still getting in from the Anker converter powering the PAW. Grrr....
Squelch on setting 6
Solution three:
Fit a thrice-wrapped ferrite core to the Anker Feed Line.
Squelch on setting 2.
Harmony and bliss.....
.
Notes:
a. The new voltage regulator for the radio is VERY RF quiet, but not very efficient. Not too bad on receive (1 W), but only about 65% efficient on transmit (11 W). So it is wasteful of energy, and needs a heat-sink. You could also run the PAW from a voltage regulator, which would be fine if you have a generator, but no good if you run on batteries. So for battery opps, the Anker is the only choice.
b. However, while the Anker is a great unit, it is still pumping some RF back down the 12v cables that feed it, turning your whole electrical system into an RF transmitter. Bad news.
The huge ferrite core I used came with the radio, and is meant for the 9v lines that feed the radio. But it made little difference there. So I took this core, and thrice-wound it onto the 12v cable feeding the Anker, and the radio interference dropped immediately.
I then tested a 2m long 12v cable to the Anker. All the cable leading up to the ferrite core was RF quiet, while all the cable on the Anker side of the core was RF active. (You only need to bring the Anker feed-cable next to the radio feed-cable, and you get interference.) So by placing the ferrite core right next to the Anker, the amount of cable causing interference is minimal, and the radio goes quiet.
So I am now running on squelch 1 with the PAW off, and squelch 2 or sometimes 3 with it on (some frequencies are more naturally noisy than others.)
Happy listening....
P.S.
The voltage regulator is a T-220 9v unit (L78S09CV). Cost 43p from Farnell.
Plus two capacitors, which were about 2p each.
And a simple circuit that even I could understand and solder....!!
Note: This voltage regulator is not big enough to run a PAW, and is of the wrong voltage...
RE
