[Motorola] Flaky Quantar Antenna Relays

[Eric Lemmon]

Jay,

Interesting!  What is the part number of this relay?  Armed with a
failure-prone part number, I may be able to find and SRN.  Please also
answer the other questions I posed earlier.  My company has six Quantar
UHF machines in service at another location, and they have been
trouble-free.  (But those are repeaters, which don't have T/R
relays..;-)

One thought just occurred to me:  If the TX delay is set to zero, or to
an interval that is too short, the PA may turn on before the T/R relay
is fully in the TX position.  There should also be a delay on the back
end, to allow the PA output to decay before switching back to receive. 
If these delays are not correct, relay destruction is almost
guaranteed.  I have not set this parameter up myself, since there are no
Quantars at my location, but I think it's worth looking into.  Have
lightning or power surges been ruled out?

73, Eric Lemmon WB6FLY

"Coote, Jay" wrote:
> 
> Eric,
> Another failed today.  This one was fresh out of the box, a warranty replacement.
> In this case the relay N/C coax center pin shorts to ground.  I had another like that
> 4-5 months ago, as well as one that would not close.
> 
> -----Original Message-----
> From: Eric Lemmon [mailto:elemmon@impulse.net]
> Sent: Friday, September 19, 2003 9:03 PM
> To: motorola@mailman.qth.net
> Subject: Re: [Motorola] Flaky Quantar Antenna Relays
> 
> Jay,
> 
> Since the Quantar is the high-tier flagship radio that Motorola offers,
> you should get your replacements free of charge from Motorola.  If you
> don't let them know about the high failure rate of these relays, they
> can't work on the fix.
> 
> I'm curious:  What is the failure mode of these relays?  Is the coil
> burning out, or are the contacts burning?  What power level is used?
> What band is used?  And the $64,000 question:  Is there a ferrite
> isolator connected between the PA output and the relay?
> 
> 73, Eric Lemmon WB6FLY
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