[BC] Re: AM Loads

[Mark Croom]

When I put an AM-1A into WNWC a few years back, I rocked the common point
just a little bit to minimize VSWR as shown on the transmitter's metering,
which brought the ammeters and transmitter power meter to a set of numbers I
think were almost textbook I'm thinking even the trim setting on the antenna
monitor was just about where it had been years earlier the last time the
thing was swept. I also recall my reflected power numbers are very much like
Ron's--I can't imagine it was over six watts with full modulation, but this
goes back several years so my memory isn't as clear as it once was.

The phasor was supposed to be set up for 50j0 so I always assumed (with no
bridge or sweep generator available) that I had rocked it to 50j0. I'm not
going to lose any sleep over it, but it's an interesting exercise to think
about how maybe I rocked the phasor to match the transmitter somewhere "off"
of ideal.

Mark
MN

On Wed, Mar 25, 2009 at 4:22 PM, Ronald J. Dot'o Sr.
<ron.doto at comcast.net>wrote:

>
> From: <towers at mre.com>
>
>  I sounds like there is a mismatch in the X. Keep in mind that the X side
>> will transform with cable length to something not 50 ohm R at the TX.
>>
>> Sweep the load at the ATU input and the TX going into the line.  If there
>> is any mismatch on the X side beyond it's sweet spot, then it won't play
>> no matter if the R might be 50 ohms at the TX.  No BE TX will.
>>
>> You also might have a transmission cable problem...
>>
>> MM
>>
>
> The AM-1A TX output goes through 3/4" foam filled 50 ohm heliax to a rocker
> type antenna switch with the switch output heliax going to the ATU input a
> short distance away.  There is maybe 15' of heliax for the whole run from
> the TX output to the ATU input.
>
> Once the ATU is adjusted for min reflected things run fine so I doubt that
> I have a coax problem.  I have about 4 W reflected CW and about 6 W with
> full modulation.
>