I can tell you this there is a world of difference between 800w and
2.5k or even 1.5k for that matter. I am in 0 land and very hard to
break the coasts on a good day at times so a little extra helps
break those pile ups.
Fred N0AZZ
Sent via the Samsung Galaxy S6 edge+, an AT&T 4G LTE
smartphone-------- Original message --------From:
[email protected] Date: 09/18/2015 1:16 PM (GMT-06:00) To:
'Edward R Cole' <[email protected]>, [email protected]
Subject: Re: [Elecraft] Product Suggestion - 500W Dummy Load
Forgive me in advance if this is a stupid question.
Is there any reason you have to tune at full power? It seems to me that
tuning can be accomplished easily with much lower power. The same
thing goes
for the ATU to the antenna. I don't see why we need more than a few
MW at
most for the ATU to Antenna link.
Rightly or wrongly when I was in the hobby the first time I ran a
TS-850
into an SB-220 to an MFJ roller tuner connected to an antenna switch
feeding: 80m inverted V, 30m/40m rotatable dipoles, and a triband beam.
Whenever I tuned on the inverted V or outer band limits of where my
antennas
where tuned I ended up putting labels on the ATU on cap position and a
number/clock combo that represented a roller inductor position for
each band
area I cared about. It ended up I rarely had to tune up anything one
the air
because I knew where the antenna tuning was using just the Rig and ATU;
tuned the APM into a paintcan MFJ load then switch it inline. I was
all set
and never had issues when I needed to kick in the horses.
Now my debate is 500w vs 800w... there's a larger difference between
500w
and 800w than between 800w and 2.5kw signal wise if I understand
correctly...
Jerry Moore
AE4PB, K3S - S.N. 010324
-----Original Message-----
From: Elecraft [mailto:[email protected]] On Behalf
Of Edward
R Cole
Sent: Friday, September 18, 2015 2:00 PM
To: [email protected]
Subject: Re: [Elecraft] Product Suggestion - 500W Dummy Load
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]
