[Motorola] Quantar Base Station Antenna Relay problems?

[Eric Lemmon]

Jay,

I recall that the MICOR T/R relay on base stations was controlled in a
manner that energized the relay first, and then enabled the RF power
amplifier after a short time delay.  Likewise, the PA was shut down before
the T/R relay signal was removed.  The purpose was to ensure that the T/R
relay was fully closed before RF power was applied to it, and that RF power
was off before the relay was released.  This practice seems reasonable and
proper, to avoid arcing of the contacts.

Although I do not claim to know much about Quantar stations, I have learned
from a Quantar buff that there is a "right way" and a "wrong way" to
energize the T/R relay in a base station, and the latter way tends to burn
up T/R relays.  It might be worthwhile to review the wiring of your T/R
relay coils to ensure that the time delays are working properly.

73, Eric Lemmon WB6FLY


-----Original Message-----
From: motorola-bounces at mailman.qth.net
[mailto:motorola-bounces at mailman.qth.net] On Behalf Of Coote, Jay
Sent: Thursday, September 20, 2007 10:44 AM
To: motorola at mailman.qth.net
Subject: [Motorola] Quantar Base Station Antenna Relay problems?

Over the years, we have gone through a lot of antenna T/R relays in
Quantar base stations.
The failure alarm is two beeps, indicating a low PA... probably the
relay not always making full contact on transmit.
It seems like these relays are finicky-
 
Any observations?
 
Thanks,
Jay