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[TowerTalk] Problem with R-7

To: <>
Subject: [TowerTalk] Problem with R-7
From: (Joe Reisert)
Date: Tue, 01 Jun 1999 19:32:54 -0400

I am quite disturbed by messages like this one about the Cushcraft R7
Cushcraft. In this message people accused me of not answering or helping
with their pleas for assistance about the R7. I did design the R7 but I did
that in 1990/1991 and I left Cushcraft in July 1992. That is almost 7 years
ago! I went on to form my own commercial antenna company and am still busy
and affiliated with the new owners as I prepare to eventually retire and
really enjoy DX !

In the mean time there has to be well over 10,000 R-7 antennas in use
around the world since they built almost 5,000 in the first 15 months of
production! I haven't received even a single thankyou (no less monitary
compensation) for help rendered to R-7 users from Cushcraft since I left
there in July 1992. In the case of the letter below, I believe I did answer
same with the part value in question (more on that later).

Why do people insist that I should still help them after all these years?
After I left Cushcraft, I heard that design changes were subsequently made
to the R-7 antenna. People called me from all over the world with problems,
some of which resulted from changes that were made after I left. After
leaving Cushcraft, during the night I'd get telephone calls from the
Pacific that got me out of bed and calls from Europe that would get me out
of the shower in the morning before I left for my new work. Letters came
all the time. It got so bad, I had to send packets of same to Cushcraft and
ask them to please do their own customer service. They didn't pay the
postage either! 

Cushcraft had made changes to the R-7 and they had to own up to same. For
several years, it was tough to get even on the air as I'd get all these
calls from R-7 users with questions and complaints about Cushcraft service.

Furthermore, Cushcraft company policies apparently changed with respect to
replacement parts. I think the so called R-7 "matching network" went from
$75.00 to $150. At that later price, one can often purchase a used R7 for
about that price complete!

Anyhow, the part I think they are referring to below (if Cushcraft didn't
change same!) is the capacitor shunted form the upper toroid input tap to
ground and was a  27 picofarad silver mica or ceramic capacitor at 500
volts (I think). I don't have a spare but that value is not critical and
should be easy to obtain.

So please guys and gals, no more hate mail. I'd like to have a life of my
own and my charity to Cushcraft has to end. If the people are unhappy with
the R-7, contact Cushcraft. If Cushcraft customer service can't help or
replacement parts are over priced, than chose another antenna (or supplier).


Joe, W1JR

>>Hi Guys,
>>Got the below email, so am putting in on TT for help.  Please
>>to Joe, N3JW.  Thanks.
>>Ted Leaf, K6HI
>>Kona, Hawaii
>>From: Joseph Adams <>  Save Address  Block
>>To: Ted Leaf <>,
>>TO:             The Ham Gang
>>Subject:        Help!
>>We have been able to form a new ham club at a local school
>>Learning Center, across from Haney Tech) which serves
>>"difficult" students in
>>the middle to high school grade levels. The early success in
>>this venture has
>>exceeded expectations and young lives are literally being
>>Our problem is the station's R-7 HF antenna (a 40-10 meter
>>ground independent
>>vertical type) which has become defective. Attempts to
>>the defective
>>component have hit a wall (Cushcraft insists on us buying the
>>entire MN-7
>>matching network for $150, even though the unit is easily
>>serviceable <4
>>screws secure the cover>, and the ARRL and several individuals
>>have failed to
>>follow through with their promises going back almost 8
>>You appear to be the last hope and follows is our request for
>>project. Please contact me if:
>>1. You can possibly "id" the part. (description below)
>>2. You know someone who you think can help (persons @ ARRL,
>>Engr, or??)
>>3. You have an inroad with Cushcraft (around the Mktg Dept)
>>4. You know someone with an R-7
>>5. You could make an educated guess as to part and its value
>>from a
>>schematic of the MN-7 Network unit (I'll scan the info and
>>e-mail to    you)
>>6. You know where we might post this request on the Internet
>>Obviously, we are trying to avoid the very tedious and
>>time-consuming approach
>>of subbing and trying different values and parts in the MN-7!
>>Someone out
>>there has got to know the answer. (BTW, we e-mailed the
>>network's designer,
>>Joe, now retired from Cushcraft. No response)
>>Here's the general info. The antenna suddenly failed to show a
>>low (below
>>2.5:1 swr) on any band. It had been doing so. Checked the
>>system from
>>exciter, thru coax, connectors and connections, to the
>>Next, dropped
>>antenna and opened MN-7 matching network at the bottom of the
>>radiator. Found
>>"disintegrated" (not charred or burned) component located just
>>to the left and
>>between the two toroidal xfmrs on the circuit board.
>>This is the only component in this location and is easy to
>>It appeared
>>to be a high voltage type disc capacitor.
>>Electrically, this "unknown" is in parallel with the
>>output/input leg of the
>>two toroid xfmrs (between them) and the ground (coax shield
>>radials). Its the only component there, as otherwise it is a
>>direct connection
>>between the 2 xfmrs! This "thing" just connects from that leg
>>Thank you for taking the time to read this info and for
>>considering trying to
>>help us. We'll cover research expenses, buy the part from you
>>(if you can
>>supply) and otherwise make this worth your while.
>>Its for a good cause!
>>73, N3JW   850-747-5500(w)   271-2588(h)
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