[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Date: Sat, 26 May 2001 14:58:31 -0500

Hi Wayne,

Long time no talk to.  Glad to hear from you but sorry to hear that you
are having so much trouble. I have had a little success with the beacon
and with some QSO's with a simple setup but it has been difficult.  I was
originally very encouraged with my results with a Drake converter with
easy mods and a 21 turn helix.  That was back in January when the low
squint angles were happening at perigee.  Range was often 10K or less. 
Now minimum squint happens at a range of 60K.  If I remember my radar
range formula form many years ago, if you double the range it takes 12 db
more system performance to have equal performance.  Since we are dealing
with one way communications that would be 6 db instead of 12 but that
still means that the signal is 12 to 15 db down from what we were
receiving in January.

Since January I have installed all the G0MRF mods in the Drake and put up
a Trans System 3733 with the stub cut out.  I'm using both with the
original crystals.  Both are connected to a 21 turn helix.  I can hear
the beacon at maximum range and a good squint (less than 15 degrees),
usually about 4 to 6 db above the noise (sometimes a little stronger)
with the 3733 and 1 to 2 db out of the noise with the Drake.  I have had
a few successful QSO's with the 3733 with only about 3 db signal to
noise.  I can hear signals with the Drake but they are not strong enough
to copy.  I'm sure I would not hear the beacon now with the Drake without
the G0MRF front end mod.  I have a DEM preamp kit to put up and I think I
am going to put it in front of the Drake since it has one of the 2450 mhz
filters in it now.  I will keep you posted.

I'm sure that the "right" way to go is with a dish antenna and a
commercial converter if your interest is communicating.  My interest (and
the interest of several others on the BB) lies along the experimenting
line so I intend to continue my experiments because this is just too good
an opportunity to pass up.

I don't have any fancy test equipment.  I'm the radio equivilent of a
"shade tree mechanic".  I do have a couple of the 2.4 ghz antenna bridges
that I built from info in the AMSAT Bulletin and a weak signal source
that I built around a 16 mhz crystal (with point to point wiring would
you believe).  I may go to a dish antenna when I get through playing but
the use of the helix antenna has allowed me to tweak on the system and
get some idea of the results.  It's simple to build and easy to point so
it takes a couple of the variables out of initial testing.

Don't give up.  Keep plugging.  This really is an exciting time for me. 
I haven't had this much fun in years.  I don't think the standards have
to be commercial quality communications.  That's why it's called Amateur
Radio.  I gave up HF when the standard got to be 2KW into stacked full
size forty meter beams at 175 feet!

73's de Jess - W4MVB
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org