[1000mp] ARB-704 and Yaesu Mark V

[Kelly Jones]

I can testify that even though the Mark V *should* not have a issue with
older amps, I experienced this very problem.  After about 6 months connected
to my LK-800, about 1 in 25 unkeys the relay would "stick" and appear as
though the attenuator had been engaged.

I didn't think much about it until another 6 months had passed and it would
occur about 50% of the unkeys.  I was certain the problem was in the amp's
keying circuit as I could not reproduce the problem using a VOM on the relay
jack on the back of the radio.  However, when I had a friend over looking at
my amp, just for fun we tried his meter on the radio.  Low and behold, we
could reproduce the problem with his meter, but not mine.  His just happened
to draw more current than mine I guess.

After a nearly $200 repair bill I put a ARB-704 between the radio and amp.
2+ years later, no problems have resurfaced.

GL & 73
Kelly - N0VD
 

-----Original Message-----
From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
On Behalf Of Bob Martin
Sent: Tuesday, November 28, 2006 10:41 AM
To: 1000mp at mailman.qth.net
Subject: [1000mp] ARB-704 and Yaesu Mark V

Why you need the ARB-704

 

Amplifiers can damage radios if the amplifier has too much relay control
voltage, voltage spikes, or excessive current on the relay control line.
Such damage often appears as "stuck" or "sticky" transmit relays in exciters
or shorted transistors on transmit control lines. In most cases where the
radio is damaged, the system transmits normally but the external amplifier
stays locked in a "transmit" mode. This prevents receive signals from coming
through the amplifier with normal levels whenever the amplifier is in the
"ON" or "OPERATE" position.

 

Above is the reason I have placed the ARB-704 between my Yaesu Mark V and my
AL-80B.  However I was told that the Yaesu Mark V will not allow this type
of damage to occur and my having the buffer between the rig and the amp is
overkill.  What is the real true?

 

 

 

 


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