At 04:09 AM 3/18/2007, you wrote:
Hi Group,
Can anybody out there enlighten me on the power amp failures on
the earlier Kenwood TKR-750 Repeaters? I recall that Kenwood was
scrambling around changing these under warranty when the 750 was
first released.
I have just removed one from service that was only pushing 15 Watts
@ 7 Amps (Set for High power).
This particular repeater has already suffered dry joints around
the PA stage which was not the cause of fault this time.
Can any Kenwood dealers shed some light on this common problem and
suggest the replacement P/A part number for around 150-160 MHz?
<---I have yet to see a Version 2 PA fail whereas with the pre
Version 2 repeaters, PA failures were not uncommon (Version 2's have
been out for around 2 years now and the easiest way to ID them is the
programming software used - KPG-91D). Then again, if you had a pre
Version 2 set for high power in repeater mode, I am not one bit
surprised it blew up - you do know they are rated for continuous duty
at the 25 watt level only, yes?
Interestingly we replaced the -750 with a Vertex VXR-9000 repeater
and commissioning tests revealed about 3 dB better sensitivity than
the 750's for 12dB Sinad.
<---Perhaps the dealer you acquired them from didn't properly align
the front end - in well over 100 TKR's that have flowed through us, I
have yet to see one that didn't meet SINAD spec once they were tuned
to the customer's channel(s).
Ken
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