Hi All,
My Cantenna has sat in a bucket since I built it many many years ago.
No seen it as yet from our house move last month, but have not seem any
oil stains as yet. I am sure the boss would have told me!
73
Tim
gm4lm
On 18/09/2015 19:00, Edward R Cole wrote:
Don't have much to say:
Had a Cantenna from Heath in the 60's - knocked over; spilt mineral
oil on the floor, threw can away!
I have acquired "dry" loads over the years rated into UHF and
sometimes to mw at flea markets and swaps. My highest power load is
500w Sierra with power meter and switch for 150 or 500w (probably good
to 1000-MHz). Have a couple Bird terminations rated 50w. Most can
handled double their rating for short duration.
The hardest duty on my loads is when optimizing the output of a new
unit where I'm keyed up longer than I should.
But I do have a question on how adjusting a tuner into a 50-ohm load
saves one from transmitting a signal once the tuner is connected to an
antenna that may not be 50-ohms. On 600m my inverted-L is Z = 0.8
+j680. Tuning into a 50-ohm load does nothing to help match the
antenna. The amplifier is solid state with input and output
transformers (no adjustment).
I think, unless you use a high power tetrode or triode, that no one
tunes amplifiers anymore. Solid state amps are broadband and need LP
filters to keep from amplifying harmonics. BTW my 2m-8877 is capable
of 2000w* RF output so pretty hard to find a dummy load to take that.
Fortunately the amp does not change much so very little tuning is ever
needed (of course I am on a small segment of one band about 200-KHz
wide). Of course the answer is to tune antenna at lower power and
hope the High Power amp will always be looking at 50-ohms.
I do not have a QRO 2m antenna tuner but the antenna SWR < 1.25 so
only the anode tuning needs a light adjustment occasionally (loading
has not be adjusted for 8 years). My "dummy load" has 19.2 dBd gain
and radiates well.
*I operate at 1365w CW which allows for about 9% variance in meter
accuracy to stay legal.
73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[email protected]
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