[Heathkit] Need A One Ohm Variable Resistor

[Gary H. Harmon, Jr.]

IP-28 manual number 595-1092-05 dated 1969 shows R-14, the ONE ohm variable
resistor, part number 11-124, as the HIGH CURRENT LIMIT control.  A
schematic I got off the web shows R-14 as a .18 ohm resistor with no pot.
Unfortunately, there is no date on the schematic.  It would be interesting
to know if the variable or fixed resistor is the later version.

73,

Gary H. Harmon, Jr. - K5JWK
6003 Archwood
San Antonio, TX 78239-1504
210.657.1549h / 210.884.6926c/t

"Retirement means every day is a Saturday except Sunday"
http://www.grissomroadcoc.org


-----Original Message-----
From: heathkit-bounces at mailman.qth.net
[mailto:heathkit-bounces at mailman.qth.net] On Behalf Of manualman at juno.com
Sent: Sunday, September 29, 2013 2:38 PM
To: krkaplan at cox.net
Cc: heathkit at mailman.qth.net
Subject: Re: [Heathkit] Need A One Ohm Variable Resistor

You all have to remember that the Heathkit schematics are directly related
to the manual they came out of. The majority of the Heathkit manuals have a
specific "595-xxxx" associated with them. If changes were applied to the
design of a piece of equipment or changes applied to the manual to reflect
printed errors or clarification of assembly processes which required the
manual to updated, a suffix dash number, "595-xxxx-01"
was added to the manual code. With each iteration of the manual, the suffix
"dash code" (-01, -02, -03, etc.) was increased. From what I can see that is
floating around the web, (i.e. same schematic in multiple places around the
web) you all probably have the original or first design released for
manufacture. I have here several original IP-28 manuals labeled 595-1092-02
and 595-1092-05 and they both have the "High Current Control" (1 ohm pot)
and take note that there were several other component additions to the
circuit. To answer your question Ken, the R designation is R14, Part Number
11-124. As Heathkit progressed through the years, they also decided to also
include the specific manual part code on their schematics and external
Illustration Booklets. This also helped reduce the confusion of multiple
documents or diagrams having different information. Unfortunately, there is
no way to tell by physically looking at a piece of Heathkit equipment what
manual iteration it applies to since Heathkit also issued separate service
bulletins to update a piece of equipment and sometimes they even included
separate update manual pages with the manual that came with the original kit
to update the manual and the kit building process.

Pete, wa2cwa
http://www.manualman.com

On Sun, 29 Sep 2013 11:23:05 -0700 Ken Kaplan <krkaplan at cox.net> writes:
> Pete,
> Do you know the R number? Perhaps my schematic is incorrect? R13 is 
> the
> 100 ohm "Current Control" pot. I don't see a "High Current Control".
> 
> Thanks,
> Ken
> 
> On 9/28/2013 7:23 PM, manualman at juno.com wrote:
> > In the IP-28, the 1 ohm variable is used for "high current
> control".
> > Clearly marked on the schematic.
> >
> > Pete, wa2cwa
> > http://www.manualman.com
> >
> > On Sat, 28 Sep 2013 21:27:23 -0400 Bill Cromwell
> <wrcromwell at gmail.com>
> > writes:
> >> On 09/28/2013 09:03 PM, W. Harris wrote:
> >>> Don't think I have ever seen a one ohm pot, but then there are
> >> lots of things I have never seen.
> >>>
> >>> Bill - K5MIL
> >>>
> >>>
> >> Hi,
> >>
> >> I saw one that was less than an ohm in some solid state audio
> gear.
> >> It
> >> was worn out and I could not find a replacement. I used the thing
> as
> >> a
> >> parts mule after that.
> >>
> >> 73,
> >>
> >> Bill  KU8H
> 
> 

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