[Heathkit] HW-8 tuning capacitor

Fri, 04 Apr 2003 13:45:03 -0600

How about a group buy, to take advantage of the considerable price break
when ordering a large quantity vs. Onzy and twozy.  Just at  thought.
73 Saad N5FF

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of John P. Cummins,
Sr.
Sent: Friday, April 04, 2003 12:11 PM
To: heathkit
Subject: [Heathkit] HW-8 tuning capacitor

I got this from QRP-L.  If it has already been posted, I apologize but I

know that are a lot of folks with HW-8s that would like to replace their

tuning caps.

Pickett, AD4S

...........................

I'd long ago given up hope of finding an exact, drop-in replacement for
the
VFO tuning capacitor in the HW-8. Every now and then someone asks how to
fix
the plates on theirs, since they sometimes fall off the shaft.  (The
problem
is caused by the amount of torque that the reduction drive can supply,
as
explained below, and continuing to turn the knob after the capacitor
hits
the end stops.) Although they can be put back in place it can be a pain
and
may not last forever, and it would be better to have a replacement
capacitor.

Suddenly, like a bolt out of the blue, I got e-mail yesterday from Larry
Baker, WB5OFD, telling me that he tracked down the company that made
them--still in business--and found that they can still supply the
capacitor.
He said he's looking at a lot of overtime coming up at work so I offered
to
post the info for him. He really went beyond the call of duty in
tracking
down the company, and HW-8 owners will be grateful for years to come :-)

And you don't have to own an HW-8 to take advantage of this, since the
capacitor can be used in any VFO that you might want to build.

Here's his info--

HW-8 VFO Tuning Capacitor

For anyone with an HW-8 collecting dust because of a broken VFO tuning
capacitor you may take heart, an exact replacement is available.

I recently purchased an HW-8 in which the rotor plates had become
detached
from the tuning shaft.  BIG PROBLEM.  Or at least I thought so.  This
HW-8
was destined to become a spare parts donor.  After removing the
capacitor
from the case I noticed the Heathkit part number 26-152 stamped into the
frame, as well as the letters ASP*7703.

After a few days of attempting to remember (talking with some old
timers) or
discover (search the web) who or what ASP stood for, I got lucky.

ASP stands for American Steel Packaging or American Star Products
depending
on what they manufactured and when.  As you can see from above, 26-152
ASP*7703 is a Heathkit part number and a manufacturer code.

ASP is now known as Oren Elliot Products.  They are located in Edgerton,
Ohio, and their plant facilities have been producing capacitors since
l925.
They are the largest domestic manufacturer of air-dielectric variable
capacitors.  Their web site can be found at www.orenelliottproducts.com.

With thanks to Mr. Steven Elliot I was able to obtain the following
information:

The VFO tuning capacitor in the HW-8 is a model NS-51, with direct
drive,
and two rotor and two stator blades with a 0.032" air gap.  It has CCW
rotation, mounting holes tapped for 6-32 threads, with a trimmer and
copper
stator blades.  This capacitor has a range of 5.2 pF to 15.1 pF.  The
trimmer can add 2-15 pF to both the minimum and maximum.

This capacitor, as well as others, was manufactured for the Heathkit
Company
product line over many years.

Mr. Elliot was also able to shed some light on how this capacitor could
be
easily damaged.  The vernier drive on the HW-8 is a reduction drive
(planetary) with a probable output torque of about 100 inch ounces.  The
26-152 can only stand about 20 inch ounces of pressure (at the end of
the
stop) before succumbing to damage. You would only have to exert an input
torque force of about three inch ounces on the VFO knob, with the
capacitor
at the end of its rotation, before possible failure.

I purchased the last 26-152 that was still in stock.  However, the good
news
is that Mr. Elliott can provide a newly manufactured replacement
capacitor,
identical to the original 26-152.  Contact him at:  Oren Elliott
Products,
telephone (419) 298-2306, fax (419) 298-3545, or e-mail: [email protected].
In
case this gets passed on to someone without e-mail, their postal address
is
128 W. Vine St., PO Box 638, Edgerton, OH 43517 USA.

Current pricing is:

1 capacitor:  $14.00
2 capacitors:  $11.50 ea.
5 capacitors:  $9.50 ea.

OEP also has a slightly different capacitor that may be suitable for use
on
the HW-8.  It has the same capacitance value; however the shaft is 0.25
inches longer and it has a built-in 8:1 planetary reduction drive unit.
This acts as sort of a viscous slip clutch, slipping when the capacitor
reaches its minimum or maximum rotation. Use of this capacitor would
help
prevent damage as described above but will necessitate a number of
changes
to the original Heathkit design. A new mounting bracket would be
required as
well as ensuring the VFO dial markings track correctly since this shaft
will
rotate 8 times faster than the rotor.  I will experiment with this very
soon
and determine if it is feasible.

If anyone needs an HW-8 VFO tuning capacitor, contact Mr. Elliot and
request
a direct drive, 26-152 replacement.    Please be sure to thank him for
supporting QRP ARCI and hams in general.

Larry Baker - WB5OFD [email protected]

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