[Elecraft] KPA1500 fan mod done - MUCH better

[exbpi at comcast.net]

Dave,

So, are these mods documented somewhere on the Elecraft site? I have been unable to locate them. Further, I can't even get Elecraft to respond about when they will provide schematics for the KPA1500.

Thanks

Mike
K7PI


-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of Dave
Sent: Thursday, June 4, 2020 22:41
To: Eric Norris <norrislawfirm2 at gmail.com>
Cc: elecraft at mailman qth. net <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] KPA1500 fan mod done - MUCH better

Yeah PSU fan noise is on par with the fans in the Flex 6700 now. PC is almost completely silent. Thinking of locating the amp, radio, and 4O3A 2x8 antenna switch in my garage in a half height server cabinet. Then I could hear myself think, but maybe I don’t want to hear myself ;-)

The two chip resistor mod on filter board was fun. I have experience with surface mount rework so no big deal. One resistor was the size of “16” onthe date on a penny (2016).

Other mods - they installed zener diodes tonthe gates on the LDMOS devices to protect against overdrive. That is one thing the LDMOS devices do not like.

Mybamp uses a pair of NXP 1K50H devices which I feel are more rugged than BLF188 and 189s. I heard early amps used the 188s but no proof of that.

Have fun! 

73
Dave

Sent from my iPad

> On Jun 5, 2020, at 1:10 AM, Eric Norris <norrislawfirm2 at gmail.com> wrote:
> 
> 
> I had completely forgotten that I did this mod, and the two resistors mod.  That, and the piece of grit or whatever that was stuck in one of the PSU fans making it scream like a banshee, took the KPA1500 PSU fan noise from being intolerable to unnoticable.  
> 
> Good times!  Ain't it grand!  
> 
> 73 Eric WD6DBM
> 
>> On Thu, Jun 4, 2020, 4:59 PM <rocketnj at gmail.com> wrote:
>> Hi All,
>> 
>> 
>> 
>> Received the new LED board for my KPA1500 power supply. Easy to swap 
>> out, six plugs and two screws. You can move one plug at a time to the 
>> new board so there is no chance of screwing anything up. To put the 
>> screws back in I suggest a Phillips screwdriver with magnetic tip. It 
>> took more time to remove the 16 screws from the top cover than to swap the board.
>> 
>> 
>> 
>> THANK YOU Elecraft!
>> 
>> 
>> 
>> 73
>> 
>> Dave wo2x
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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