[ARDF] US ARDF Championships: 2m AM receivers...

[Matthew Robbins]

Joe (and all),

    I just wanted to drop you a note about the Ackerly receiver.  When
I spoke to you on Friday, I was giving you my best guess based on the
events we did in Cincinnati, mostly based on Dick's and Bob's use of
both receivers side-by-side, plus Brian's trouncing of me with the
ROX-2, and my use of all of them in the parking lot at our events.

    One thing about all our recent practices (although I did miss a
couple, so I might be wrong), is that we didn't have any distant
transmitters, and that might be a deciding factor despite better
performance up close.

    After the 2m event on Saturday, which was very difficult in the
RDF-sense, there are a few more things to consider.  Please consider
my attributions to specific people as hearsay---I might have
misunderstood what they really said.

    1.  I seemed to do okay with the Ackerly.  I have figured out how
to get a decent bearing.  It's slower than I'd like, but it works. 
The trick is to rotate the antenna very slowly.  It seems like the Ron
Graham and other, analog receivers allow you to quickly point to the
transmitter.

    2.  Bob and Dick both used primarily the Ackerly, even though they
had the option of easily switching to the Ron Graham.  Dick said he
used the Ackerly 99% of the time.  I think that both thought the Ron
Graham couldn't hear the distant transmitters from a long way away.

    3.  Brian said his ROX-2 could hear all the transmitters from all
over the course, but about 1km or so east of the finish beacon, it
gave him squeaker tones that tracked MO.  I mentioned my Ukranian 80m
radio with the 4kHz/100kHz bandwidth switch, which on 100kHz gives you
whoopee tone even when you're off frequency (a handy feature), and he
might look for a way to do something like that.  I'm building a ROX-2,
so I'm interested in that as well.

    4.  I got the impression that the Ackerly attenuator display (and
the experience of several 2m AM events) kept me out of trouble a few
times, especially on the way to 5, where I stopped twice to check what
turned out to be reflections, and decided to continue east because the
signal strength seemed too low.  Another example is the start (on 2m),
where the corridor pointed (more-or-less) east toward 3, but I decided
to go north to the gravel road.  When 3 came on, it wasn't strong
enough to make me go after it.  I'm still not sure if 3 is the right
first transmitter.  I felt like going to 1 first gave me a lot of
information about the course that I wouldn't have had if I'd started
into the low area between the start and 3.  I meant to ask the people
with the Ukrainian and other 2m gear how it worked for them.

    I think the biggest lesson from the 2m course (for the people who
didn't already know), was that 2m AM is a lot harder than 2m MCW, and
you really need to practice with 2m AM.

Matthew
Cincinnati, Ohio, USA