[1000mp] Re: SWR Problems with Mk-V Field

[Mike Schatzberg]

Hello Carl:

I connect my SWR bridge couplers directly to the radios with a double male
connectors, I also do the same with my amplifiers, the couplers are
connected exactly in the same way.  I use no coax at all.  The coax used
between the coupler and the dummy load should be short and of high quality,
with good connectors.

When checking SWR with the Mark V, I find the most accurate readings to be
taken in CW mode, while sending a series of dits, with perhaps 30 watts or
so of output.  You will notice that the readings will be different for SSB,
if you try to take measurements in that mode also.

I find excellent agreement between my outboard SWR measurement and the on
board meter using this method.

Should you be driving an amplifier, the cabling between the amp and the
driver is another special case, in order to obtain the lowest possible input
SWR into your amp without the use of your on board tuner.  There is an
article on my website which addresses this issue which you may find
interesting.

73 and Happy DXing,

Mike
W2AJI
http://home.earthlink.net/~cherokeehillfarm/id2.html


----- Original Message ----- 
From: <carl at UDel.Edu>
To: <1000mp at mailman.qth.net>
Sent: Wednesday, January 23, 2008 11:05 AM
Subject: [1000mp] Re: SWR Problems with Mk-V Field


> Dear Ron,
>
> Thanks for the input!  Originally, I had 2 ft of RG-8 going from the
Mark-V Field to an antenna switch, and then 2 ft of RG-58 going from the
switch to the external watt-meter/SWR meter, and then 2 ft of RG-58 attached
to the dummy-load.  With your thoughts in mind, I went ahead and
disconnected all of this and attached the dummy load directly to the Mark-V
Field via 2 ft of RG-8, and everything stayed the same, except everywhere is
was 1.4:1 came down to 1.3:1, and on 10-meters, the SWR went from 1.3:1 to
1.4:1.  It may be that the on-board SWR meter is just sensitive to the coax
used (the coax is commercial, but obtained through a local CB supplier); on
the other hand, it might be an indication of a problem developing.  Just
wondering what others have experienced.
>
> Thanks again, Ron, it is greatly appreciated!
>
>
> Best Regards,
> Carl - K3NTH
>
> >
> >Message: 4
> >Date: Tue, 22 Jan 2008 19:15:11 -0500
> >From: W4LDE-Ron <w4lde at cfl.rr.com>
> >Subject: Re: [1000mp] SWR Problems with Mk-V Field
> >To: All about Yaesu 1000mp <1000mp at mailman.qth.net>
> >Message-ID: <4796870F.90402 at cfl.rr.com>
> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >
> >Carl,
> >
> >The change may be caused by the length of the coax between the rig and
> >the remote tuner.  I had a similar difference in readings using
> >manufactured coax w/ connectors between the amplifier and the rig and
> >the amplifier and the remote tuner.  See if you have some different
> >lengths of coax and see what readings you get.  I average about .2
> >differences after I changed the lengths.  Frankly I think that you will
> >never see the same readings and from your data below that meters are
> >within tolerances.
> >
> >73 de
> >Ron W4LDE
> >
> >carl at UDel.Edu wrote:
> >> I have a Mark-V Field hooked up to a G5RV and matched with a LDG
AT200Pro autotuner.  I noticed the other day that my autotuner and my
external watt-meter were claiming a 1:1 match, but the SWR meter on the
Field was claiming 1.7:1.  While I don't expect everything to always read
identical, I thought this rather strange.  I switched to a 50 ohm
dummy-load, and did some investigating using the dummy-load:
> >>
> >> 160m - 1.1:1
> >> 80m - 1.1:1
> >> 40m - 1.0:1
> >> 20m - 1.3:1
> >> 17m - 1.4:1
> >> 15m - 1.4:1
> >> 12m - 1.4:1
> >> 10m - 1.3:1
> >>
> >> All of these values were read from the SWR meter on the Mark-V Field;
the autotuner and my external watt-meter/SWR meter are reading 1.0:1 on all
bands  Might this be an indication of a problem, or have others noticed this
discrepancy?  Any feedback would be most appreciated!
> >>
> >>
> >> Thanks, and 73's!
> >>
> >> Carl - K3NTH
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> >
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