[Heathkit] RE: Heathkit Digest, Vol 55, Issue 19

[Robert P. Ward]

To the list and Joe

Hi Joe

	Don't think you will find the original parts kit to change the
power supply to an "A" model.
I recently installed a crowbar circuit in my Heath supply. I used the
schematic form ARRL Handbook, titled 28-V high current supply. The 20 A
secondary fuse will have to be moved to "see" raw voltage and add the
crowbar,
I used a 15V zener in my design. Also added a BIG diode from the regulated
output to the "raw" DC input to handle back-flow. Simple but it works..

		Bob   NQ3N





Message: 5
Date: Thu, 21 Aug 2008 18:58:11 -0700
From: "Joe Hatvany" <joekb7svi at verizon.net>
Subject: [Heathkit] HP-1144 PS
To: <heathkit at mailman.qth.net>
Message-ID: <000d01c903fa$88bc02e0$7801a8c0 at joe>
Content-Type: text/plain; format=flowed; charset=iso-8859-1;
	reply-type=original

To the list

Does any one know if  I can find a source for parts to upgrade the(  HP-1144
PS to a HP-1144A ? As it happens my HP-1144 does not have the crowbar
circuit included, on the regulator board an did some nasty things to my
SB-104A's "A" & "B" boards, and possibly rhe Output Transistors when the
un-soldered   ground pin came loose from the regulator board. (poor kit
building )
Any and advice will be appreciated

Thanks &73
Joe KB7SVI