Thanks to all who have responded. A quick up date.
Putting the dummy load on the TX port of the repeater (replace the
duplexer with a dummy load) has shown that the repeater works without
cycling - so my initial thought of something going on inside the
repeater is out the window... (Thanks Doug)
If is was spurious TX trash while the transmitter was coming up, then
after we overcame the desense with the service monitor and the TX
stabilized, then when we turned the service monitor back down, the TX
should have stayed on, but it didn't and started to cycle again
Still racking the grey cells,
Rick, N5RB
--- In [email protected], "pontotochs" <pontoto...@...>
wrote:
>
> Hi,
> I've checked the previous posts on this issue, but I am hoping that
> there is more light to be shed.
> We have a VXR 7000 that has had issues for a while as a two meter
> repeater.
>
> In the shop we set it up with its DB 4026 duplexer and 50 ohm dummy
> load and monitored the output power with a Bird thru line watt meter.
> We used a service monitor to inject the RX signal to get 10 dB
> quieting (approx 0.2 micro volt). Put the unit into repeat mode and
> the repeater will cycle (go in and out of transmit) until the RX
> signal is increased about 20 to 25 dB (approx 3.6 micro volt).
>
> Looking at what is coming in the receive port with the transmitter
> is keyed is about -75 dBw (50 watt out with about 95 dB of isolation)
> at the TX frequency, and there is little to no hash at the RX
> frequency - seeing the noise floor of the spectrum analyzer (-120 dB).
>
> Put the 7000 into base station mode, hooked up second signal source,
> set first signal source to give 10 dB quieting at the RX frequency
> (0.2 uV), set the second signal source to emulate what we saw from the
> duplexer (79 mV at TX frequency) and there was no desense. Increased
> the simulated TX voltage to better than 1 volt and still no desense.
>
> My thought is that something has gone bad internally within the
> 7000. Is there something else I need to try?
>
> Thanks in advance for your help.
>
> Regards,
> Rick, N5RB
>
