[CQ-Contest] Need a Yaesu FT-100D VHF/UHF amplifier repair source

N6KI Dennis Vernacchia n6ki_73 at sbcglobal.net
Fri Sep 1 20:05:58 EDT 2006

Does anyone know anyone that knows something about designing and repairing 

This person would have to be a super-tech or have some design experience as 
here is the situation.

A ham friend has a FT-100D HF/VHF/UHF mobile transceiver. He blew up the 
VHF/UHF output
device. Yaesu no longer has these Motorola devices in stock and apparently 
Motorola is no longer
making them. There is NO direct substitute device.

This device is the output stage for 2 mtrs and 70 cM bands ( 50W on 2 mtrs 
and 35 W on 440 mHz I believe )
It is not one of the common modules ones sees in most VHF/UHF mobile Xcvrs.
A call to RF Parts in San Marcos yielded a device that has same form factor 
and as good an
electrical parameter match as one could find.

A local ham who does a lot of servicing and has a great deal of test RF 
knowledge and test equipment, installed
the substitute device but, unfortunately the device does amplify but due to 
parameter differences etc - it also tends to go into
oscillation and tries to destroy itself. This is a common event in 
VHF/UHF/Microwave amps
when trying to substitute a device that doesn't exactly match the original.

What is needed is someone that has a good RF test equip setup and knowledge 
to figure out
what circuit mods would be needed to stop the oscillation ( if even possible ).

If someone can solve this problem, there are plenty of FT-100D rigs with 
blown VHF/UHF devices
that need someone who can effect a repair. according to info from Internet 
user groups.
When you send your FT-100D into Yaesu with this problem, I understand you just
get the rig back marked not repairable. I guess Motorola bailing out on 
making the device
....probably a minimum quantity issue, has now cause a nasty ripple in 
Yaesu's repair ability
to affect a repair.

I bet there a bunch of owners of the FT-100Ds with blown VHF/UHF PAs
that are not happy campers at the moment !

Any help appreciated.

I have no pecuniary interest in this matter

73, Dennis N6KI
San Diego

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