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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 23:53:52 -0500
List-post: <>
Hi Jim,
Right at the tubes socket pins.  73 de jay/w5jay..

On Mon, Oct 23, 2017 at 7:29 AM, Jim W7RY <> wrote:

> Where did you measure the filament voltage?
> 73
> Jim W7RY
> -----Original Message----- From: Jay Bromley
> Sent: Monday, October 23, 2017 1:26 AM
> To:
> Subject: Re: [Amps] K0HM Electronics Repair and Alpha 9500 repair
> 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
> planned.
> 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
> w5jay/jay..
> On Oct 17, 2017, at 7:31 PM, Larry P. Greenberg <>
> wrote:
>> 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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