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Old October 5th 03, 08:54 PM
Roy Lewallen
 
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Working people with one watt can be challenging, but certainly not
impossible. In the course of a few years, I worked (and confirmed) all
50 states and 33 countries on 40 meters with about 1.5 watts output.

Your antenna height is a big handicap. 7 feet is severely
low for a 40 meter antenna. While you'll still be able to hear stations
just fine, it'll produce a very weak signal from an already weak
transmitter. If there's any way possible, make the antenna higher. I'd
strive for at least 30 feet if possible; higher than that is better yet.
Another option is to use a vertical. With even a poor to moderate ground
system -- even a couple of ground radials (more would be better) --
it'll do much better than the very low dipole.

A hot transistor combined with low output power makes me suspect that
the transistor is either parasitically oscillating or trying to produce
a lot of harmonic energy. That means that you could be producing only a
tiny amount of power on the desired frequency -- much less than even a
watt. Pull the antenna off your receiver and tune around. Does the
signal from your rig sound hissy or hashy? Are the signals at harmonic
frequencies as strong as or stronger than the signal at the desired
frequency? Set up a sked with a ham that's a few miles away (whom you
can locate through a local club), and have him tell you what your signal
sounds like. Have him listen for harmonics, birdies, or other signs of
instability.

Finally, you need to be aware that a crystal-controlled transmitter can
be a big handicap these days. People don't often tune off their own
frequency to listen, and they're likely to have a pretty narrow filter,
so you're not likely to get a response unless you're lucky enough to be
very close to their frequency. That said, your success rate should be
higher when calling someone than when calling CQ, since people are more
prone to respond to a weak signal calling them than to one calling CQ.
But only if you're on their frequency so they can hear you. I couldn't
get the link to the URL to work, so couldn't look at the transmitter
schematic. However, after you get the other problems fixed, consider
modifying the rig to VXO operation (where you're able to move the
frequency a bit) if it's not already VXO.

There's no reason you can't substitute HC-6 crystals for FT-243 in a rig
like this.

Roy Lewallen, W7EL


John Sandin wrote:
I am a new technician with code privileges. I built the following CW
transmitter for 40 meters:

http://cs.okanagan.bc.ca/ve7ouc/eng/...nsmitter2.html

It's a solid state 3-watter, based on an article in QST in June 1967.
I used a printed circuit board instead of wiring everything together
directly, as the QST article suggests. So, there are many wires
running from various parts mounted on the chassis to the circuit
board.

I'm getting very little output. After tuning the transmitter, per the
specs, and measuring the output using the method suggested by the
author of the web page, I figure I'm getting 1 watt or less. I am
running this into a dipole cut for 40 meters, which is 7 feet off the
ground. I'm using fundamental frequency HC6/U crystals for 7110 and
7125 kHz. I've been trying for 2 weeks, at all hours of the day and
night, and have had no indication that anyone hears me. I've called
CQ, and I've attempted to answer CQ's. Nothing, after about 100
tries.

I know it's impossible for any of you to know exactly what's wrong,
but I'd like to see what opinions I can glean here.

Is there any reason why I should use FT-243 crystals, as specified in
the article and on the website? I used HC6/U crystals because they
were easy to get.

One of the transistors (Q2) is supposed to be heat sinked. I have put
a large homemeade heat sink on this, using plenty of heat sink grease,
and it gets so hot I can barely touch it.

Also, the transmitter chirps a bit at the beginning of each
transmission, but settles down after a few strokes of the key.

Many thanks for any help you can give.


-John Sandin KC0QWE

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