Readability reciprocity is a very interesting question. Since I'm a 6M
operator, things might be a little different for me than on the HF bands,
but probably not all that much.
In contests, unless you are operating a really Big Gun station and are
solidly in the high-power category by choice, you can't run an amplifier
anyway and stay in the low-power class. So it comes down to basic DXing,
busting pile-ups, etc. How much power is enough? How much is too much?
The quality of the receiver has a lot to do with it, but an even bigger
consideration is your noise floor. Part of that is simple geography, and
part of it has a lot to do with the kind of antenna you're running. If
you're in a very quiet rural environment and using a fairly sharp yagi, then
you're going to be able to hear a pin drop on 6M. Couple that with a good
receiver, and you probably have at least a 6 dB receive advantage over 90%
of the guys you're going to be working, who are mostly going to be in a
typical suburban environment with plenty of man-made QRN. This is kind of
the conclusion I came to, anyway, and it's bearing out pretty well. I run
400W on 6M SSB/CW, and that seems to be just about right.
You really have to experiment. If you find yourself struggling to hear more
than 20% or so of your contacts, then I would say you're running too much
power. If you find yourself losing a lot of QSOs where you can copy the
other guys Q5, you're probably running too little power for your low-noise
environment. (And how I envy you!)
To the point of the original post, I agree that putting a 200W amplifier
module in the K3 would probably not be worth it, and putting 400W inside the
box is almost certainly unfeasible. Go with an external amp.
Bill / W5WVO
Martin AA6E wrote:
Brian has some good points. Personally, I think the jump to 400-1000
Watts from 100 is so great that you really need to think of a separate
amplifier. 100 W is clearly enough for 90% of QSOs (that I make,
anyway), and it would be a shame to compromise a good 100 W
transceiver package to allow for an internal QRO amp and/or power
supply.
After > 40 years as a ham, I finally broke down and bought a
used/upgraded SB-220 for my station. It has helped on occasion, and
it's kind of an interesting piece of gear in its own right. One
thing I have noticed, though, is that if I call CQ at 100 W, I get
nice replies. If I call CQ at 1000 W, I get lots of very weak
replies. That's the flip side of "reciprocity". Yes, it's good to
have a good receiver, but you may need to strain to work those
marginal Q's. (Actually, that's half the fun, especially if it's
Swains Island.)
73 Martin AA6E
Brian Lloyd wrote:
On May 10, 2007, at 10:06 AM, Elliott Lawrence wrote:
One thing that would help would be an additional option for a 200w
capable radio ---- the K3D!!! I wonder if that is a future
possiblity??!!
Do you really think that 3dB will be enough of an advantage? That is
all you will get when you go from 100W to 200W.
It seems to me that one needs at least 6dB to make enough difference
to make the effort worthwhile. 6dB seems to be the difference
between, "I know you are there but I can't quite copy you," and,
"QSL." If you started at 100W then you would need 400W to make that
difference. I tend to think that 10dB is about the right increment and
that
would be 1000W. That leads me to feel that if you need more power
than 100W you are going to need an external amplifier.
And then there is the issue of path symmetry. Path loss is going to
be the same in both directions. Given that most rigs out there are
in the 100W range the signal arriving at each end will be the same.
Hmmm. Oh! The K3 is likely to have a much better receiver than the one
the
other guy is using. So if he is using 100W and you have acceptable
copy on him you might need a 3dB-6dB improvement in your signal in
order to deliver an equivalent readability signal to the other end.
Interesting thought. Maybe a 200-300W PA wouldn't be such a bad idea
after all. 73 de Brian, WB6RQN
Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com
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