A year ago I had a low-band VHF interference problem that was caused by a solar
charge controller. Switching from an MPPT style charge controller to a less
efficient PWM charge controller cleared up the problem. Might be worth double
checking by disconnecting the panels since the charge controll
Thanks - no battery chargers on site as all solar powered. There are solar
charge controllers, though I think I have discounted these.
No fluros either.
All equipment was switched off for a test, so any SMPS should have been off.
Cheers,
Brett
--- In Repeater-Builder@yahoogroups.com, DCFluX
Hi Mike,
thanks for your post - I'll think about this a bit more. There is no isolator
on the TX - will add one (and BP filter) when I next go to site this week.
The radio is synthesised.
Regards,
Brett
--- In Repeater-Builder@yahoogroups.com, "wb8vlc" wrote:
>
> "I have inserted a 6dB pad
Hi John,
I thought we may have a dubious TX issue - either spurs or as you say something
unstable or oscillating.
I replaced the TX. It had no impact on the problem. The issue appears to be
external to the TX.
Also I have terminated the duplexer into a 50ohm load and looked at the RX port
Paul,
no fluro lights on site. Actually no lighting at all - the site is solar
powered so little capacity for lighting.
No repeater ocntroller - the RX is directly connected to TX via a very simple
(passive) audio and PTT circuit.
I believe it is an IM product because the RX requires a CTCSS
Eric,
all cables are double shielded. No adaptors are used. There is no isolator on
the TX side. Connectors are silver plated, with gold pins.
Antenna is a single folded dipole mounted about 15m above the equipment
shelter. TX power into the antenna is approximately 15W. There are solar
p
Look around for a switch mode power supply that uses 600kHz as the
switch frequency. SMPS Battery Chargers are popular for causing this.
Also florescent twist lights are really good for making desense on
VHF.
"I have inserted a 6dB pad in the antenna port of the duplexer and found that
the IM products drop 12dB, and also curiously, the frequency of the products
change. Removing the pad reverses this effect."
The above says that it's a 2nd order mix, F1+F2, F1-F2, 2F1 or 2F2.
Since it looks to be
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