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Re: [Amps] K0HM Electronics Repair and Alpha 9500 repair

Subject: Re: [Amps] K0HM Electronics Repair and Alpha 9500 repair
From: Jay Bromley <>
Date: Mon, 23 Oct 2017 01:26:24 -0500
List-post: <>
Hi Larry,

Sorry for the delay in posting this.

I’ve had my 9500 serial number 400 since 2011 and it has been pretty much
flawless.  I had a 10m tuning issue when I first got it, that was corrected
by Brad K0HM over the phone.  I also had it upgraded by Brad before the
warranty went out.  That consisted of several parts, resistors, diodes,
etc.  The main mods was to the Hall Effect sensor and adding a new blower
bearing plates to each side of the blower motor.  The new ball bearing
plates finally solved the blower issue that sounded like a rumble after a
while or unbalanced blower.  These bathroom blower motors were always
problematic until the new ball bearing plates were designed.  The new ball
bearings replaced the sleeve bearings and the side plates are much thicker
if I remember right?  The later 9500’s had a completely different blower
assembly.  After the blower mods, the firmware was upgraded to 3.03.  All
this warranty work was done by Brad K0HM when he was working for Alpha
Power.  I loaded up the amp and took it to Colorado for the upgrade.  When
I saw Brad early that morning he said he would call me in a few hours just
to go hang out around the area.  Within 2 hours he called saying to come
pick up the amp.  It would have taken me a good day to do the work Brad did
in less than a couple of hours and I am no slouch in the soldering
department!  When I got there he was testing the amp at full power showing
me how much faster the new Hall Effect Sensor was on tuning the amp.  I
loaded up the amp and headed for home without saying an extra night as

Now on to just a few weeks ago.  My 9500 is out of warranty, Brad is now
gone from Alpha and the filament on my Chinese 8877 opened up.  I called
Brad at K0HM’s Repair Service and told him the symptoms.  He confirmed my
thoughts and suggested I take the tube out to test the filament to be sure
that was the issue.  Sure enough the tube filament was wide open!  After
getting a new tube I learned my line voltage is way too high and that
caused my filament voltage to be on the high side as well.  Not sure if I
would have got more life out of the old tube or not, there has been quite a
debate on this list and others on this subject.  BTW, the filament voltage
was 5.6 volts and higher at times!

Back to service, I haven’t used Alpha service since they have changed
hands, so I can’t comment on that.  However Brad K0HM has called me back
even on Saturdays, in the evenings, etc.  I leave a message or an email and
he always gets back to me usually the same day!  The last time he walked me
through adjusting the bias on the new tube over the phone.  Never did he
suggest I send the amp in like some companies would have done!  I can’t
recommend Brad K0HM Electronics Repair highly enough for 9500 service or
any legacy Alpha amps that need work!  I will continue to use Brad until I
can’t get parts for the 9500 or Brad retires and moves on!  I have been
using Alpha amps since the mid-1970s and have got to know Brad going on 20
years or so now.  Not only does Brad K0HM not only does great work, but I
trust him.  Those qualities are very important to me!

The 9500 continues to work, even quieter and smoother than new!  The first
amp I’ve ever owned that I have confidence in day in and day out.  73 de

> On Oct 17, 2017, at 7:31 PM, Larry P. Greenberg <>
> I am getting ready to send my early model 9500 in for update and
repair.  I would like to get an idea of your experiences with Alpha factory
service and also Brad’s service, K0HM.  Which is better, turnaround time,
price and, in general how satisfied were you with the updates and repairs.
Feel free to answer privately but also feel free to answer publically as I
am sure others would be interested.  I am getting the impression from the
list that Alpha have made improvements recently.  My 9500 continuously
hunts for resonance and the idling plate current is high.  Also, the serial
port doesn’t work but the USB port works.
> Larry, WA9MAG
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