greenfin2002 wrote:
> am using a 440 hub repeater to link 2 vhf repeaters. everything worked
> except the normal squelch crash. i then added audio delay boards to
> fix this now when i unkey from vhf repeaters i hear an echo. usally
> the last 2 or 3 letters of the last word that was spoken. looking for
> ideas. thanks pat
You're delaying the audio and the keyup toward the link hub, and then
delaying again at the link hub, so your receiver at the two 2m repeaters
is hearing that last few hundred milliseconds of audio coming back from
the link hub after all the delays.
I saw Kevin's reply and noted that he said the Maggiore's have very slow
squelch circuits.
One thought came to mind:
In your CAT controllers, are there any macros like in the S-Com
controllers? (I know nothing about CAT controllers.)
If so, you could trigger a macro to disable the receiver that listens to
the link hub's transmitter when the main receiver port goes active and
KEEP it disabled for a couple hundred (however many you need)
miliseconds after the user unkeys on the 2m repeater? That would keep
you from hearing your echo come back.
Of course, all this delay adds up to really slow switching and
turn-around times for a conversation end-to-end if you have to do
something like that.
Another design flaw with that option is that the above would also make
it impossible for you to send any control DTMF to the 2m repeater from
either the link hub or the other 2m repeater while it was transmitting.
What CTCSS encoders and decoders are you using? If you could use
something that would transmit a proper "reverse-burst" on the link
radios to the UHF repeater, and the tone decoder there also knew how to
decode it, and it would slam the receiver closed as soon as it heard the
phase-shift, you could remove the audio delay board at the hub repeater
completely. No squelch crashes would happen there, and you'd be getting
rid of your user squelch crashes at the user repeaters.
This assumes that the UHF hub is only used for linking, and no users
talk through it. If you did the "reverse-burst" thing and people on
non-commercial radios talk through the hub repeater, you'd hear a
squelch crash on them, but not on the users from 2m.
Nate WY0X
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