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

AO40 hamfest station

Last Sunday I set up an AO40 demonstration station at the North Shore Radio
Club hamfest in Grayslake, Illinois, USA (north of Chicago).  The operation
went reasonably well, considering what could have gone wrong.

I had no trouble setting up my portable AO40 antennas.  I had used the
portable antennas 3 times before at home, so I knew how to do it and I knew
that the antennas, tripod, and cables were working properly.  The downlink
antenna was a G3RUH 60cm dish, patch feed, DEM preamp, and TSI
downconverter.  The uplink antenna was a 7x7 element RHCP Arrow antenna on a
1m long boom.  The crossboom was a 67cm piece of painted wood attached to a
heavy-duty camera tripod.  Four bricks hung from a hook under the center
riser of the tripod.  The bricks weigh down the tripod so it's not prone to
blowing over in moderate wind.  The antennas were aimed manually.  For the
initial setup I used a compass and protractor to set the az/el.  But for the
subsequent adjustments I adjusted the antennas by listening to the beacon.
To do that I had a 40 foot headphone extension cord running out to the
antennas.  Adjusting az/el by ear is much faster and probably more effective
than adjusting the az/el by compass and protractor.  My 40 foot headphone
extension cord and 42 foot 9913FX uplink feedline proved to be barely long
enough for my setup.  The station was about 20 feet away from a door, and
the antennas had to be about 15 feet from the door to have a clear view of
the satellite at the beginning of the hamfest.

Inside, the station consisted of an FT-847, Astron power supply, external
speaker, Heil Proset, and 2 additional headphones.  I occasionally ran audio
to a speaker, but people could generally hear much better with headphones
because of the high ambient noise level at the hamfest.  Next to the station
was a 486 laptop computer running InstantTrack and InstantTune.  I used
InstantTune the entire time, even though the Doppler changed extremely
slowly.  InstantTune made it much easier to switch between SSB and CW.

I made only 6 AO40 contacts.  I was hoping to make more contacts, but it was
difficult because there were very few stations on AO40 to make contact with.
Also, I was running the AMSAT table by myself, and spent the majority of my
time answering questions, not operating the station.  Signals from AO40 were
fairly good when the hamfest started at 8 AM with a squint angle of 13
degrees.  But by 10 AM the squint was about 20 degrees and signals were
quite weak and there was virtually no activity on the transponder.  The
transponder shut off at about 11AM (MA130) when the squint was 22 degrees.
My first contact was with GW3XYW in Wales, followed by contacts with VE2DWE
(twice), VE3EAF, WD5GQM, and W4LWT.  The highlight of the day was the second
contact with VE2DWE.  That's when 11 year old Mark, KC9AUZ, made his first
satellite contact.  Thanks Luc for digging us out of the noise.  50W to the
7x7 yagi was a marginal uplink when the squint was 20 degrees.

Here are my tips for operating a portable AO40 stations at a hamfest:

1. If possible, locate your antennas in an area where most of the visitors
will walk near it.  It attracts a LOT of attention.  I put a sign on the
tripod saying "Come inside and see/hear the AMSAT OSCAR 40 satellite
station".  The sign also says "Warning: stay 5 feet back from front of yagi
(500W EIRP)".

2. Don't forget duct tape!!!  My feedlines had to cross a traffic aisle to
get from my assigned table to the door.  I used a LOT of duct tape to make
sure people didn't trip on the cables.  I also used duct tape on the AC
power cable which ran some distance on the floor.  And duct tape to hold the
AMSAT banner in place.

3. Put an identifying sign in front of your station.  My sign said "You are
welcome to operate the AMSAT OSCAR 40 satellite station".

4. Get announced on the PA system during the hamfest if possible.  I didn't
ask for that, but I was pleased when the hamfest organizers did announce the
station on the PA system.  Obviously they thought a live AO40 demo was an
interesting "feature" of their hamfest.  They knew I was there because I
made special arrangements to get a table with nearby AC power and near a
door with a view of the southern sky.

5. Get a helper.  It was extremely difficult for one person to demonstrate
station operation and answer general questions about satellites or the AMSAT
merchandise.  I didn't sell very much stuff, and I wonder if I would have
sold more if I (or a helper) was able to actively promote the merchandise
more.  I was expecting a very experienced helper, but he had to cancel at
the last minute.

6. Test all your stuff in advance.  I thoroughly tested my portable antenna
setup in advance.  I concluded that my original camera tripod wasn't rugged
enough for the windload of a 60cm dish.  So I bought a heavier-duty tripod
before the hamfest.  I didn't have any antenna problems at the hamfest.  But
I did have a minor radio problem.  I used the FT-847 internal CW keyer for
the first time (at home I use an external memory keyer), and it took me a
long time to figure out how to enable the keyer.  I thought it was enabled
in the menu, but it turned out to be enabled by a front panel button which I
had never noticed.  Yes, I felt like an idiot when I finally found the
"PROC/KEYER" button.

7. Bring multiple headphones and match the volume on the headphones (or have
a separate volume control for each headphone).  People will hear much better
than if you use a speaker.  And you won't be prone to feedback when

8. Get a table at the end of an aisle and put the station at the end of the
table.  Then onlookers can stand around 3 sides of the station.

9. Above the radio's frequency display, have a sign that explains your
antennas and especially your downconverter.  The most frequent question I
heard was "why are you receiving out of band on 123 MHz?".  My "you are
welcome to operate the AO40 station" sign DID explain that outside was a 2
foot dish outside receiving on 2401 MHz, with a downconverter mixing down to
123 MHz.  Apparently most people didn't notice it.  Perhaps because the sign
was facing towards the traffic aisle, but away from the operating position.

Unfortunately, the probability of a good AO40 pass occurring during the
typical hamfest is 20% or less, depending on the alon/alat.  It will be
impossible have an AO40 demo at other local hamfests on 09 June and 21/22
September.  But I should be able to run an AO40 demo for 4000 Boy Scouts at
the local "Scout Jam" on 19 October.  The footprint on Saturday night will
include Europe and the Americas.  This is "Jamboree On The Air" (JOTA)
weekend.  The purpose of Jamboree On The Air is to let Scouts talk to other
Scouts via ham radio.  So I hope that many other AO40 satellite stations in
Europe and the Americas will participate in JOTA.  I want to encourage
others to set up a portable AO40 station that weekend at your local Scout
Jamboree, or offer your home satellite station for JOTA if there isn't a
local Jamboree.

Wayne Estes W9AE
Mundelein, IL, USA

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org