[AMRadio] WTB - MURCH UT-2000A


Rob Atkinson ranchorobbo at gmail.com
Sat Jun 12 19:38:54 EDT 2010


Bob,

I don't dump a rig full power into a tuner and start adjusting it.  I
don't own a 610 but I agree that would not be good for the 610.   I
have never owned one of those Murch tuners (I remember the original
QST article though) so it may be true that the Murch won't handle the
full output of the 610 with a lot of modulation and a long
transmission.  Before giving up on it, it sounds to me like what you
are having difficulty with is the time it takes to find a match.  You
need some kind of low power signal source that is enough to get a
reflected power measurement, 10 watts say, or one of those SWR
analyzers.  I'd tune the 610 into a dummy load like you have been
doing and put the tuner and antenna on an analyzer so you have plenty
of time to mess with it.  If it is working okay you should be able to
find a way to transform your feed line to 50 ohms if there is nothing
bizarre about it and your antenna, then you can switch it off the
analyzer and switch the 610 on it and fire away and see if the Murch
arcs or gets hot.  I do that with all my tuners here because the
environmental conditions outside are always changing and affecting the
antennas a bit and they are always interacting with each other and I
have to mess around when I change bands and ground things or let them
float (I can never remember which, it varies with the band and the
antenna) so the analyzer is a must have before I start dumping power
into a matching network.  Sometimes I'll get a slightly false reading
because the analyzer is getting some signal from something else but it
gets me in the ball park and I can put about 10 w. into the tuner to
hit the reflected power null.   Of course none of this is any good for
ops who are running around chasing dx and contesting but it is fine if
you are like me and squat on one frequency for an entire evening hi
hi.

If none of this works, why not sell the Murch to the fellow who is
looking for one and fix yourself up a big L network if you are using
coax feedline.  Get yourself an aluminum box, a few 30 KV doorknobs,
an air variable cap like an amp load cap, roller inductor and a
ceramic switch for the doorknobs.  With a little wiring and testing it
will probably sit there and handle the 610 all day.   I did something
like that but I used banana plugs and jacks and jumpers and left it
open because I don't have kids or pets.

73

Rob
K5UJ

On Sat, Jun 12, 2010 at 5:22 PM, rbethman <rbethman at comcast.net> wrote:
> I don't care if Marconi himself designed it.
>
> It will NOT tune a BC-610 to ANY antenna!
>
> Even after setting the BC-610 to the 400W ME-165G 50 ohm dummy load
> first.  It would melt the final before it managed to "match" anything.
> 250THs don't grow on trees!
>
> I have the manual.  I have checked it against the schematic in the manual.
>
> I'd take one of the Heath tuners, the high power ones, ANY day over the
> Murch!
>
> I don't know how long others have been at this, but that has been my
> experience since 1980!  There is equipment, then there is purported
> "ultimate" that is nothing but junk.
>
> Bob - N0DGN
>
> On 6/12/2010 6:12 PM, Robert Nickels wrote:
>> The Murch UT-2000A is a commercial version of the classic "Ultimate
>> Transmatch" designed by Lew McCoy and featured in the July 1970 issue of
>> QST and numerous ARRL handbooks.    It's called "ultimate" because it is
>> able to match coaxial-fed antennas, end-fed wires, and with the addition
>> of a 4:1 balun, balanced feeders.   The manual is on BAMA and I can send
>> you a copy of the QST article if you need it.
>>
>> Add a good SWR/power meter and once you learn how to tune it,  the Murch
>> will match most anything you can hook to it, 160-10 meters, up to a KW.
>>
>> 73, Bob W9RAN
>
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