In article , mike
writes:
On 23 Sep 2003 05:09:01 GMT, (Avery Fineman)
wrote:
Silly me, I put them all in parallel.grin. I am a mechanic with some
electrical knowledge, but not much electronics. So the resistor should
be in series with the diodes to limit current.
A side effect I noticed after installing the 1N914 diodes was images
scattered across the bands. For example, wwcr on 3200 was also on
2300. Another gentleman posted me link in the antenna group where he
found the same thing happening.
Might the resistor in series with the diodes reduce this side effect?
The effect should not be there with or without diodes, with or without
any resistors...unless there is some VERY big RF source out of the
receiver's tuning range that is supplying energy to the diodes and
thus causing the "mixer" effect.
It might be possible if you have some Local Oscillator energy leaking
out to the antenna connection, but even that is unlikely given "modern"
(in the last couple of decades) receiver design.
The diodes should not have any effect on anything but a few millivolts
of any signal arriving on your antenna. A non-conducting diode simply
shows a junction capacitance to the rest of the world. That's a minor
reactive discontinuity to the antenna connection.
It might be possible that some unusual circuitry in your receiver presents
a DC Voltage at the antenna port. If so, it might cause one of the diodes
to conduct. It would be better then to AC-couple the back-to-back diodes
to the receiver through a capacitor of 0.001 to 0.01 uFd to eliminate that
possibility. You should be able to measure any DC potential at the
antenna port with a high impedance multimeter.
Len Anderson
retired (from regular hours) electronic engineer person