I have survived another one.
I operated in my first VHF contest way back in the last century sometime
around 1980. Since then, other than the impact of digital modes, the
biggest difference I've noticed is the lack of gear bursting into flames or
the magic smoke escaping from high dollar parts during my more recent
contests. I contribute this to the effort I now put into keeping Murphy
out of my ham shack. I avoid the scourge of Murphy's Law through thoughtful
planning, careful implementation and avoiding costly last minute foolish
ideas. However, I still on occasion fall into the trap of making major
changes and updates to my station weeks or even days prior to a major
operating event such as VHF contests. Prepping for the September VHF
contest was no different.
During the fantastic tropo the past couple weeks I realized I was missing a
lot of contacts because I wasn't monitoring some bands while operating
others. There wasn't any good reason for this deficiency. I have multiple
rigs, they just aren't connected in a way to take advantage of owning them.
So, about two weeks ago I decided I need to change how my radios were
connected to the various antennas and amplifiers. After all, how hard
could this be?
Before The VHF contest, I was set up as follows:
. 50MHz is on my FT-2000 and a HF-6 1200w amp.
. 144, 432 & 1296MHz I use an IC-9700 with the DX Shop PTT multiplier.
Each band has a dedicated amplifier and a mast mounted LNA powered
from the radio RF connector with a bias-T.
. 144MHz - 1KW eb104 SSPA
. 432MHz - 400w eb104 SSPA
. 1296MHz - 70w AMSAT SSPA
. 222 is an IC-375A and a Larcan 1KW RF deck
222 & 50MHz were not an issue as they are each "stand-alone" for weak signal
operating. I also have a second of each rig I use as well as a second HF-6
SSPA.
Where there is no backup, and I where am limited is in the antennas. I only
have one 6m yagi and the other bands are multi antenna arrays on a single
tower/H-Frame that I use for both terrestrial and EME. My other (backup)
IC-375A is used for FM on a separate antenna. The other (backup) IC-9700,
also used for FM, was connected to separate 440 & 144 antennas for working
repeaters.
When I normally operate HF or weak signal modes, I use a (rare) NCS
Multi-Switcher that connects mic, CW, audio & PTT for up to 4 radios to a
single microphone/headset, CW key and PTT foot switch. This allows me to
"move" from rig to rig with only a single button push.
My goal was to be able to maintain the ability of working both FM and weak
signal modes as well as use both IC-9700s as weak signal radios during the
contest and any future band openings without swapping out cables and wires.
The intent was to do this without spending a lot of money and get it done in
time for the September contest in 10 days!
First, I needed a second PTT box for the other IC-9700 that I ordered from
the DX Shop in the UK. I had it in about 5 days! The rest was all cables
and wires. I ordered RCA to RCA cables from Amazon and had them in two
days. I also needed 10ft of Heil wire to connect the mic audio & PTT from
the NCS Multi-Switch to the backup IC-9700. This I ordered from DX
Engineering knowing I would get it in 3 days. However, the US Post Office
decided I was not getting it in 3 days. They decided to sit on it in
Richmond for 3 days and it arrived Friday, the day before the contest.
The biggest challenge was the switching bands/antennas/control between both
IC-9700s. I decided I only needed to be able to switch 2 bands, so I left
each radio connected to 2 meters as they already were and built a control
box to switch the 1296 and 432 bands of either radio to each SSPA and LNA
bias-T as needed. This lets me monitor/operate any 2-band combination from
the IC-9700s at the same time. To do all of this I used a $14 Amazon
circuit board with a pair of optically isolated DPDT relays, some miniature
toggle switches, a couple RF relays, a plastic project box and some power
pole connectors I had laying around. In hindsight, I realized except for
the RF relays, I could do all the switching with just 2 DPDT toggle
switches!
I had it all connected the day before the contest, and it performed
perfectly the entire weekend.
Apart from the lousy propagation this was a normal VHF contest weekend that
included at least one equipment issue. No flames or smoke, but an issue
requiring attention anyway. My antenna array H-frame is slightly out of
balance and if I let the elevation go above 72 degrees, it will not come
back down. This is something that is easy to fix, but I had been ignoring
it as watching the elevation and stopping the rotor before it reached 72
degrees was easy enough. However, while chasing some multipliers on EME
Saturday I noticed I was no longer being heard or hearing anyone else. It
turned out the moon had reached an elevation of 78 degrees and of course the
array followed and was now stuck and would not come back down. To fix
this, I had to lower the crank-up tower and get on my man-lift and fasten an
old cast iron window weight to the bottom of the H-frame. I should have
done this months ago!
VHF contesting is so much fun..
de K3SK
Dave Buckwalter
FM07 - Farmville VA
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