[1000mp] Re: Mark V high SWR with amp

[Michael W Elliott]

For all those who answered my post I wish to thank
you.
I got some great advise and used them as part of my
problem resolution.

PLEASE EXCUSE ANY GRAMMAR OR SPELLING ERRORS.

Short recap:  My Yaesu Mark V had high (full scale)
swr while my Alpha 99 output and Bird Wattmeter showed
good swr.

Here is the outcome.


I eliminated the Nye Viking tuner to make the testing
simple.  Basically had the rig to amp to Bird
wattmeter.  When I felt I had determined the problem
solution I finally re-introduced the Nye Viking Tuner.


 


So here goes.

1. I talked to Yaesu and because the rig was ok in
normal power output the problem pointed to the amp or
another place in my set-up. 

2. I next talked to Alpha and explained my situation
on the Alpha 99.  I talked to Glen at Alpha.  He
indicated there was a 50 ohm resister located
underneath the bottom of the amp and to start there.
You take the bottom cover off underneath and you will
see it immediately.   This resistor is connected to
the SO-239 for the input side.  This resistor is about
3 to 4 inches long (black) (you can't miss it).  It
seems one end of the clips holding the resistor in
place completely came off.  Now the clip was still
attached to the resistor but not to the chasis. This
would be the end opposite of the SO-239.  This may
have happened in transit last September when I shipped
the amp back to Alpha for a problem that was under
warranty and fixed. For whatever reason the clip was
dangling or hanging down on one side. Again, the
resistor was still in the clips on both ends but only
one end was held by a ceramic standoff on the end of
the SO-239 and not grounded or connected directly to
the chasis.  I tested the resistor to be certain the
value was still good and re-attached the clip with
resistor in place to the chasis.  

3. I grounded all equipment to the tuner. The tuner to
a number 4 wire to my ground rod.

4. I am awaiting a Line Isolator from Radio Works
coming in on Monday 2/12/05 to be sure to eliminate
the  possibility of stray rf on the coax.  Guess I am
going all out now.

Post testing:
I tested the Alpha 99 and it appears to be doing ok
with the Mark V.  Mark V shows low swr as it should
with matched antenna set-ups or by using the Nye
Viking tuner for 75/80 meters sloper. 

Now on the Alpha 89 I believe I also helped eliminate
some marginal jumper cables and it also appears
happy..

Thanks to all who responded.  I got a lot of great
info from you guys.

INCIDENTLY:  In talking to Yaesu you Mark V guys who
run an amp using the Alpha 99 or 87a might want to
check your output power from the transceiver and move
it down to 100 watts max output from the rig. The menu
option values are 10/75/200 watts but my Mark V puts
out 25 watts more than what the menu says.  Look in
your Alpha 99 / 87a Manuals to see the caution about
running anything over 100 watts through the 99 or 87a
because of damaging the resistor - even if it is in
stand-by.  My Mark V puts out 250 watts with no
modification done on the transceiver.  I have even
called Yaesu and it said it is not uncommon for the
Mark V to put out 225-250 watts out from the box.


73s
Mike

--- Michael W Elliott <kq0b at sbcglobal.net> wrote:

> I have started to notice a high swr reading on the
> input side (transceiver) while running with amp.
> This
> problem is becoming more persistent.  The SWR meter
> goes full scale on the Mark V.  Rig internal tuner
> is
> off in the menu so that is ruled out.  This does
> does
> not happen using 200 watts output. I have checked
> the
> swr with 250 and all is fine.  Once I turn the amp
> on
> and transmit I get the swr problem in the rig - does
> not matter if cw or ssb.  
> 
> I see no problems on the outboard meters with a
> Bird,
> Nye Viking or even on the amplifier output meters
> indicating output swr problems. Everything looks
> normal  there.  
> 
>   
> I seem to remember a thread sometime in the past
> about
> a similiar problem.  Can someone recall or give me a
> clue to the problem.
> 
> So that I do not waste a lot of time on the
> reflector
> please respond directly.
> 
> Thanks
> Mike
> 
> 
> 
> 
> =====
> Michael W. Elliott
> THE INSIDE ADVANTAGE -
> RETIREMENT - LEISURE, REST and ONLY ELECTRONIC MAIL
> PAYMENTS
> Servant to Bridgett, Collin and all my Creditors
> St. Louis County Missouri
> 

=====
Michael W. Elliott
THE INSIDE ADVANTAGE -
RETIREMENT - LEISURE, REST and ONLY ELECTRONIC MAIL PAYMENTS
Servant to Bridgett, Collin and all my Creditors
St. Louis County Missouri