[TenTec] Low power output on Argonaut V

[George, W5YR]

I have probably posted too much on this topic, but the author alludes to a
point that can cause problems if not taken into consideration.

Most 'amateur' dummy loads are really not exactly 50 ohm resistive loads.
They are "close enough for government work" but still not exactly 50+j0
ohms. As a result when attached to a length of coax and thence to the rig,
whatever the actual impedance of the load is at the operating frequency, the
impedance at the input of that coax will be different, and the difference
may or may not be significant. As a result, an external SWR meter placed in
that line somewhere, even if perfect and few of them are that hams can
afford, will read one value of SWR and the meter in the rig can read another
value. Small differences usually, but differences nonetheless.

So, the point here is to attach the dummy load in the test being recommended
by the shortest possible connection. In this way, whatever the impedance of
the load is, that is for practical purposes the load the rig with see.
Sticking the load on 10 ft of coax can make a noticeable difference and just
confuse matters further.

Enough from me on this topic, but this is a rather subtle point that a lot
of folks might overlook when dealing with problems of this sort.

73/72, George
Amateur Radio W5YR -  the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"
<mailto:w5yr at att.net>





----- Original Message -----
From: <Wj5mh at aol.com>
To: <tentec at contesting.com>
Sent: Sunday, June 29, 2003 11:50 AM
Subject: Re: [TenTec] Low power output on Argonaut V


> In a message dated 6/29/2003 11:45:49 AM Central Standard Time,
> ghoffman at spacetech.com writes:
>
> > I'd start by assuming the internal meter is correct, and look for a bad
> > connection between the radio and the external tuner, power meter, etc.
> >
> > 73 de Gary, AA2IZ
> >
>
> Amen...  Check the obvious first.  Connect a borrowed (stand alone) dummy
> load directly to the Argonaut V output through a short, known good, newly
built,
> 50 ohm coax jumper, and see what the rig's meter reads.
>
> You didn't say what tuner you were using, but many have problems with
cheap
> female coax connectors.  Also, your coax jumper may be defective (ground
not
> connected).  Remember, you're external swr indicator is at the end of the
jumper
> inside the tuner.
>
> Good luck.
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec