Hi Mike,
I've not been following this thread, but the first thing I would say is that
your friend probably feels as bad as you do. Personally, I would count
friendship way above a couple of tubes, or indeed, any equipment <smile>. I
have amateur friends, and yes, they occasionally suggest things that I know
are wrong, but then, I'm sure I often do the same. Neither of us are
'idiots', we just have differing experience.
If I was your friend, I too would think the problems must be with your
station, and I too would go looking for issues!
As I said, I've not been following the thread, but I can possibly answer the
differences between your vertical and a trapped vertical. Basically, you
are relying on the tuner to find a good match, whereas a trapped antenna
will attempt to give you resonance on the bands it covers.
The big question I would be asking, is what is the SWR for each band on your
vertical. This is the SWR without the ATU. It could be 2 to 1 on 40,
meaning the ATU is just tweaking the impedance, but it could be 30 to 1 on
75. I would not personally put high power into this, even if you can get a
1 to 1 match using an ATU.
As I say, check the antenna SWR on each band.
Best wishes, Kelvin Marsh - M0AID
Working to improve accessibility for radio amateurs with disabilities
www.active-elements.org
For accessibility evaluations of amateur equipment and MP3 manuals
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Michael Ryan
Sent: 07 April 2014 03:34
To: [log in to unmask]
Subject: Unun balen fed vs traps
Hi all:
I know this discussion has been posted to the list many times but I wanted
to gauge an opinion again.
Does anyone know if an Unun fed antenna, mainly a vertical, induce high
currents and voltages back through a coax feed line?
I'm getting an indication that my 43 foot vertical is now the cause of my
apparent tube failure and if don't stop using it, I'll blow the crap out of
the rest of my station.
My own tuner, after a period of a couple of months of use, started having
trouble tuning out a 75M 6/1SWR spike but behaved perfectly on 40/10,
including the DX contest with my amp running 600W CW with 50W of drive.
The tuner I have now, handles this antenna from 75M to 10, didn't try 160,
with my amps 600W CW no problem. My own tuner, is currently on a wire
antenna, handling the SSB output from a HeathKit SB-220, about 1200W, 75/10M
with no problems.
Put my tuner on my antenna, it will tune perfectly and handle 200W on 75/10M
but put 500W CW through it, the amp hissed. This may have lead to the 20M
issue a couple of weeks ago but I don't think my amp is made of cardboard.
LOL
Now how would a trapped vertical be different?
I'm very confused, discouraged and most of all scared.
I don't know what's to gain by BSing me but its starting to look like the
gentleman who's been a helping friend since I got my license is doing just
that or is simply wrong.
73:
Mike VO1AX
|
