HI to all.
For what its worth, this 20--25 foot coax length figure is what Collins Radio
Corp
always spec'd fro connecting the KWM-x series radios to their amps. Read this
in
the setup and op manual for their 30-S one.
73,
Gary...wa6fgi
Joe Isabella wrote:
> Also, try lengthening the coax between the amp & antenna. Hi-Sierra
> recommends 20-25 feet of coax for their screwdrivers. I have a HB copy of
> the HS, and indeed it makes a big difference in how it tunes.
>
> Joe, N3JI
>
>
> "Carcia, Francis A HS" <francis.carcia@hs.utc.com> wrote:
> Noninductive metal film resistors can take a beating. I suspect you
> have a ground loop or loose connection. The amplifier input is not tuned so
> it should look like a passive load to the exciter. You may have lost a
> bypass cap or ground connection inside the amp when mr. elk hit you.
> You might try a dummy load to see if the tuning between the exciter and
> amplifier changes to get a match.
> gfz
>
> -----Original Message-----
> From: Paul Marbourg [mailto:zborg@comcast.net]
> Sent: Monday, October 10, 2005 3:15 PM
> To: amps@contesting.com
> Subject: [Amps] Metron MA 1000b Misbehaving
>
> Hi there.
>
> Shortly before ramming my SUV into two large elk while mobiling during the
> WA state salmon run last month, I observed something a bit odd with my
> trusty old Metron amplifier. While fine tuning my Hi-Q 160-5 antenna (while
> stopped along side the road) on 160 meters, I was monitoring the SWR between
> the TS-50 exciter and the amp's input, as well as between the amplifier's
> output and the remote-controlled shunt inductor feeding the antenna's base.
> I used a MFJ cross needle peak reading VSWR right after the exciter (with 4'
> run of RG58U then on to the amp) and a RadioCraft 3000 remote sensor right
> on the amp's output (with about a 10' run of RG8U to the shunt to ground
> roller inductor at the antenna's base). When I made a flat match between
> the amp and antenna, there was a somewhat elevated VSWR (1.5:1 ?) between
> the exciter and amplifier. When I made a flat match between the exciter and
> amp, there was a significant VSWR between the amp and shunt inductor at the
> antenna's base. Given the wavelength on 160 meters, I would not expect any
> significant variation in VSWR at the two different path insertion
> measurement points. Therefore, I am beginning to suspect that the input
> swamping resistors in the Metron may have aged to the point that their
> non-reactive resistance has shifted away from the 50 ohm network value.
>
> As I recall, the design uses four paralleled 200 ohm 2 watt metal film
> resistors for swamping and another set of the same for an input attenuation
> pad prior to the four port input splitter. Does anyone out there have some
> experience with repairing the Metron? I have yet to do a visual on the amp.
> May I presume to hold the four paralleled 200 ohm swampers as the primary
> suspects? These guys are reactively compensated with L1 & C3. Any history
> of C3 failure? I would expect to see heat damage on the swampers if they
> have been overdriven by accident/failure.
>
> Thanks & 73,
> Paul WN7T
>
>
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