Posted by
Cady, Fred on
Jan 04, 2011; 12:16pm
URL: http://elecraft.85.s1.nabble.com/Curious-phenomenon-with-doublet-on-80m-tp5885101p5888448.html
Hi,
I had a similar problem last year in ARRL SS where the power output
jumped around. Gary suggested doing the power calibration again. I had
little trouble getting it done in the Utility but doing it manually got
things settled down again. I'm not sure that this fixed whatever the
problem was (why did the calibration have to be done again) but it fixed
the symptoms as it hasn't done it again. Well maybe it did it a bit once
or twice at C6AKX this year.
Dunno. Try it.
73,
Fred KE7X
-----Original Message-----
From:
[hidden email]
[mailto:
[hidden email]] On Behalf Of Igor Kosvin
Sent: Monday, January 03, 2011 4:24 PM
To: 'Kok Chen'
Cc:
[hidden email]
Subject: Re: [Elecraft] Curious phenomenon with doublet on 80m
Hi Chen,
I did connect dummy load tonight. With the dummy load the SWR at the
problematic region is fine, but I see different symptom. When I activate
tune everywhere else I see on the display: top line "1.0-1", bottom line
"30 W". Which corresponds to my tuning power. Both lines are stable and
the power meter shows accurate 30W or so. At the problematic region the
top line alternates between "1.0-1" and "--" and the bottom line reading
is very unstable - the power jumps randomly from 18W to 48W, so is the
reading of wattmeter - it is also unstable. The returned power stays
pretty low though.
The meter bars on K3 also unstable. The SWR shows one bar and it is
blinking fast. The RF is jumping randomly.
I do not have presently neither VNA nor Antenna Analyzer. I guess though
that use of dummy load pretty much exonerates antenna or tuner. The
dummy load is just one big resistor with very low reactance.
73,
Igor, N1YX
-----Original Message-----
From: Kok Chen [mailto:
[hidden email]]
Sent: Monday, January 03, 2011 2:02 AM
To: Igor Kosvin
Subject: Re: [Elecraft] Curious phenomenon with doublet on 80m
Hi Igor,
You are correct that you should try to see if the K3 will work properly
into a dummy load at 3504 kHz.
Do you have an Antenna Analyzer or VNA?
If so, I would suggest tuning the MFJ to match the Kenwood rigs, then
remove the rigs from the tuner and use to antenna analyzer to look into
the MFJ's Tx connector instead of connecting the K3. The impedance that
you read on the analyzer might give a clue as to why the K3 can't work
into it.
Vy 73
Chen, W7AY
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