> "wmhpowell" <w...@...> wrote:
> I'm looking for some Quantar "engineering level" help re: an
> interesting simulcast issue.
Does it have to be Quantar?
> I live in an area where I can hear several of high band our
> simulcast Quantars. The whole thing was installed and set up
> by Motorola including GPS stabilized time bases.
All that and $3 can sometimes get you a decent latte.
> I'm monitoring with a true "monitor": wide band IF and little
> limiting. When the dispatcher drops a dead carrier I hear little
> in the way of hetrodyne or "grunge" as it should be.
Hopefully meaning the carriers are close to each other and not
moving around a lot.
> However, when the dispatcher drops alert tones I hear a
> hetrodyne that decreases in frequency over the duration
> of the tone.
During the tones present or after the tones go away?
> My guess is that the tone is somehow pulling one of the
> VCOs in a Quantar exciter because of a lack of DC restoration
> in the modulator: a capacitor is charging and slightly
> shifting frequency.
Why would you guess that?
> I consider this to be abnormal and undesirable behavior -
> especially in a system of this caliber.
How about any Simulcast System...
> I haven't done any field tests yet. I suppose I can set up
> 2 service monitors: one to receive in the AM mode and the other
> to provide a reference carrier and then send tone to each
> transmitter, in turn. That, at least would let me isolate
> the problem to one, two, ?? radios.
Not where I'd first go/test...
> Has anyone else experienced a problem like this?
Yes
> Any Motorola engineers out there?
Can I be an Authorized Kenwood Service Station and Dealer Instead?
Or is a retired from Motorhead Field Service person OK?
> Our local tech is also baffled so I'm reaching out for ideas.
> Thanks,
> Bill Powell
Keyboard player for Lynyrd Skynyrd?
Getting serious for a hopefully brief moment...
How is the tx audio making it's way to the repeater/base stations?
Have you checked and compensated for group delay on those paths?
Got milk?
s.
