Tim,
I did some more looking and tried the tune on other bands. All the
bands, from 6 to 160 tune the first time, and to low SWR, except
suddenly 80 m fails most of the time.
I am perplexed as to what changed.
Gary
On 12/19/2010 5:59 PM, Tim Ellison wrote:
See my comments below.
-Tim
*From:*Gary Warner [mailto:garyw...@gmail.com]
*Sent:* Sunday, December 19, 2010 8:20 PM
*To:* Tim Ellison
*Cc:* FlexRadio reflector
*Subject:* Re: [Flexradio] Automatic Tune
Tim,
Comments below in maroon.
Gary
On 12/19/2010 2:26 PM, Tim Ellison wrote:
What is the value of a successful tune in the ATU form? The default is 2.1:1
so 2.0:1 would be a successful tune.
It is set for 2.1. I set the target lower to 1.1, since I was
getting really good tunes and wanted to go for even better- got a
number of tunes at 1.1 and even 1.0, and still do occasionally, but it
usually takes many attempts to get any result lower than the 2.1
result. I get the "Tune failed" more often than not, and an
indication that the SWR >10.0:1.
*/[Tim] Setting the target low will take the ATU a longer time to try
and find a better match. It will also slightly increase the
probability of getting a Tune Failed too./*
What the ATU will match is based on the complex impedance presented to it and not a particular SWR value. If you are suddenly having problems, then I would first look at your antenna system; coax connectors, have you been having wet WX and freezing temps that can play havoc on connectors, etc..
Yes, we have been having a lot of wind and rain, but the antenna is a
horizontal dipole with a long ladder line. The ladder line
terminates under the eave of my roof and gets no rain, and the
connection is well taped and secure. How would a balun act if it
were a problem?
*/[Tim] The SWR could rise if the inside balun gets too wet. I have
one on a 20m dipole that is 1.3:1 dry and will present a 2.0:1 if we
get a hard rain. That one is exposed to the WX directly. I am just
too darn lazy to drag it out of the trees to fix it and the ATU does a
good job of matching it, so I am not too worried about the
transmitter. The ATU will do nothing for the losses, so it really
doesn't matter if it is 1.3:1 or 2.0:1/*
If all that is good, then there is a possible chance that the SWR bridge is out of calibration or there could be a hardware problem (blown diode). To test this, you can connect a dummy load and see what SWR value the ATU reads it as, which should be 1.0:1. If you have more than one dummy load, you can connect the together in parallel and see if you get a 2.0:1 SWR and it should tune it to 1.0:1.
There does not appear to be anything wrong with the radio, as I
neglected to mention that I can tune a vertical antenna every time at
well less than 1.5:1. The vertical shows intermediate results during
the tune that rarely exceed 2.0:1, but the horizontal will show
results all over the place during the cycle and sometimes in excess of
300:1. If something is broken, however, why does it still sometimes
still tune successfully?
*/[Tim] It depends on the complex impedance that the ATU is being
presented from that particular antenna system. If it is at the edge
of what the ATU will match, you can get the "hit and miss" behavior
that you are seeing./*
*//*
If you think it is a hardware problem you should Contact Dudley and have him triage the issue.
-Tim
-----Original Message-----
From:flexradio-boun...@flex-radio.biz
<mailto:flexradio-boun...@flex-radio.biz>
[mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Gary Warner
Sent: Sunday, December 19, 2010 5:11 PM
To: FlexRadio reflector
Subject: [Flexradio] Automatic Tune
Can someone tell me why my Flex 3000, which is running with SDR 2.0.16,
is suddenly having some difficulty tuning my antenna? It will go
maybe ten times where the tune fails, and then the next time it will be
fine at anywhere from a perfect 1.0 to 1.4 SWR. It is set to accept
2.0 as an acceptable tune, with a target of 1.1, but when it fails, it says it
is exceeding 10.0.
Gary
WG1I
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