[NLRS] VHF Field Day modes

[Doug Reed]

One thing you should note about the FD rules is that voice, CW, and
digital are all considered separate band-modes and provide a way to
multiply your QSO points when station count is limited. Instead of
working a station just once per band, you can work them in 2 or 3
modes per band for up to 5x the points.

If your club is going to the trouble of running a VHF station,
consider adding a computer and sound card interface to that station.
You get one point for the voice contact, 2 more points for a CW
contact with the same station, and 2 more points if you can contact
them on a digital mode as well. Having the sound card interface also
sets you up to try meteor scatter mode which could increase you points
score when the band is otherwise dead...

So if you can operate all three modes, you could actually improve your
VHF point score 5X by making duplicate QSOs in alternate modes on the
same band. This is a perfect excuse for the VHF emergency services
crowd to use the FLDIGI software for real. I know that FLDIGI has all
the digital weak signal modes that you could want and you can
send-receive CW with it as well. Or you could use any other digital
sound card program you want.

There is also nothing that says you have to QSY to use the other
modes. CW and digital modes are OK anywhere in the band. So you could
call CQ on your frequency and mode of choice, and after the first Q is
made, ask if the other station has CW or digital modes and make those
Q's before you offer to QSY. Do the same on each band where you have
common equipment. You may find that CW or digital lets you make some
Q's you couldn't have made on SSB. I suggested PSK31 because it can go
14dB below the noise, WSJT can dig 24dB into the noise...

One nice thing about doing the sound card modes is that you never have
to leave SSB mode on the radio if the computer is doing the sending
via the sound card interface. And of course you can pre-load various
FD messages to automate the digital and CW Q's even more. I don't
think FLDIGI has a SSB voice keyer mode, too bad....

If you are going to do this, you might want to amend your listing in
the VHF-Blog to indicate CW and digital capability. I'd suggest
keeping your options to a minimum, perhaps just CW and PSK31 if on SSB
or CW and MFSK16 on FM? (It never made much sense to use CW or digital
with an FM voice rig, but it does meet the requirements of the FD
rules and it is FCC legal....)

Just be sure to reduce the digital audio drive levels to keep power
output low so you don't overheat your finals!!! Digital modes are
considered 100% duty cycle and most SSB rigs can't do that at full
power output. It is probably less of a problem with FD Q's since they
are short and fast, but don't blame me if you damage your finals
running too much power.....

I'm not expecting anyone to do this if 6M is open and hot. But in the
more likely case that the bands are quiet, this does offer you a way
to increase your VHF QSO points with a fairly simple station upgrade.

The most difficult part of this is getting the sound card interface
and a computer with software before next Saturday. Having a little
time to play and become familiar with the software would be a good
thing as well.... Radio City would be happy to sell you an interface,
they usually have them on the shelf. My personal favorite is the
Signalink USB because it is one cable to the computer and one cable to
the rig, but YMMV.

If anyone would like to build their own sound card interface for next
year, let me know. The main ingredient is two 600 ohm transformers and
some sort of isolated PTT keying circuit, and I can provide those to
anyone who wants to build the rest. I'm considering trying the KH6TY
interface (March 2011 QST) with a USB dongle as my next interface,
although K0BXB had an interesting suggestion in June 2011 QST....
<https://sites.google.com/site/kh6tyinterface/>

73, Doug Reed, N0NAS.