Many rovers fail to realize the advantages of using 2 operators
to increase their effectiveness. The present rules for ARRL contests permit 2 operators, as
long as there is only one signal-per-band at any given time. This means that you can have
your rover partner calling CQ and cleaning up on 6m, while you are busy racking up the points
on the microwaves. Perhaps more significantly, you can have one operator constantly combing
2 meters for needed stations much of the time. Of course this isn't as easy as it sounds.
Most multi-operator VHF contest stations have lots of cross-band QRM problems, and the situation
is far worse when all the antennas of a rover station are on the same vehicle. In general,
these problems are solveable, but not without some thinking and expense. First of all, you
should plan to have 2 radios, and a robust DC power system that can support both guys transmitting
at the same time. You will consume twice as much DC power, so you will have to either double
your battery stack, plan to operate half as long, or otherwise increase your capacity to supply
both operators with adequate DC power. In my case, I added a 2nd Jacobs DC-DC converter,
and fed it off of the existing battery string. I can get away with this, as I also have a
heavy-duty alternator installed, which can supply 170 Amps when I leave the engine running.
I think the basic step to dual-operator station design centers around adding filtering to allow
6 and 2 meters to run simultaneously. This requires a good low-pass filter on 6m and a
band-pass filter on 2m. If properly installed, this set-up will allow either station to
transmit without significant QRM to the other station. In my case, I had to add switching
to bypass the 2m filter when transmitting, as the filter is only rated for 200W, and my tx
power on 2 is close to 400W. 2m doesn't bother 6m at all. There are still some issues with
my 6m tx causing some QRM on 2m, but I think these problems are related to some loose hardware
on the antennas. My 6m halo is only 2ft above my mobile 5el 2m yagi. Loose metal-to-metal
contacts on your vehicle or antennas will create non-linear junctions, and cause a large
transmit signal to generate spurs and garbage, which can't be filtered out. Make sure
all coaxes are tight, and that there is no loose hardware anywhere near the transmit antenna.
Another consideration for dual-operator work is that of your microwave IF frequencies. I
find significant QRM on the microwave receiver (144.1 MHz IF) when transmitting on 2m
(usually 144.247 MHz or so). I plan to change the microwave IF frequency to 145 MHz. I don't
hear any 2m interference when the microwave IF receiver is tuned up to 145 MHz. Of course,
this will require changing out all my microwave LO crystals, but it should solve the problem.
Another feature which we have found highly useful is to add a band-sharing capability to the
2 radios. This means to add switching which will permit either operator to take over any
of the lower-4 bands. We found this capability very useful in the Sept 2003 VHF contest.
Both the antenna, and PA/preamp are shared by the 2 radios. I switch RF and PTT control
to the appropriate exciter, using DP3T toggle switches. LEDs indicate which op has the band.
It is necessary to switch the unselected rig into a 50 Ohm load, to prevent possible
disaster if the wrong rig is accidentally keyed, when not selected. A group of 4 transfer
relays, and 4 50-Ohm loads were used to implement this capability. It all fits into a die-cast
aluminum box about 8 x 8 x 3 inches in size. It would be nice to also share the microwave
equipment, but this is something I haven't had the luxury of thinking about yet. I'll be
happy to get the lower 4-bands under control for now. Don't forget that both operators will
need access to the rotator controls.
For most VHF contests, it is extremely important to find stations on 2m. Having 2 operators
really makes this easier. Perhaps one guy can stay back on 2m, while the other op is running
bands with the last customer. This technique was very successful for us in Sept 03. My
rover partner had a large number of stations calling in with requests for higher bands, and
he effectively queued them up, and kept them posted with the status of the microwave operations.
This held alot of guys around, who would normally have gone back to searching for QSOs on 2m.
I think this example is one of the best reasons to consider dual-op methods.
I have installed a miniature aluminum table on the passenger side of my van. It's not big, but
there's just enough space for my partner to sit his laptop, and have a little writing spave.
This is essential, if you want to capitalize on dual-operator techniques. Logging is important,
and you gotta give both operators the ability to do it conveniently. His FT-100 control panel is
"velcroed" onto the dashboard, and the aluminum angle brackets for the table are screwed into
the trim with wood-screws. It helps to have a dedicated vehicle to do this...hi. My partner
uses a headset with a boom-mic to help keep my loud voice out of his ears. This works well.
With some study of past contest results, and some experience, you will learn which stations
have multiple bands,and which stations you can expect to work from various locations.
This information is vital to effective contesting, as you can hunt these guys down, and work
them on other bands for a large point-return in the contest (also fun-points). I'm not suggesting
that you pass anyone else by in your search for these big-gun stations...just suggesting that
you learn which other stations have the capability to give you the big points, and hunt these
guys down! The more you operate, the easier this will become. Many guys lament about the
problems of hearing a desired station as he was just QSYing off to another band, where he
couldn't be copied any more. This is part of the life of a VHF contester, and you just have
to do the best you can. If you are on 2m, and getting ready to QSY with someone else, I
suggest that you stick around on 2 for a few more possible calls. Most other stations won't
mind waiting a minute or so for you to clean-up the 2m stations. If you're really lucky,
you can talk the other guys into QSYing with you, and then work the whole pileup again on
the higher bands. Of course this may require more adept antenna manipulations, as you go
higher in frequency. It usually works pretty well on the lower 4 bands, though. Having
2 operators makes finding stations on 2m much easier. It's amazing how many guys we still
miss, but now, at least, with 2-guys, we are much less likely to miss them. ("I never heard
you from FM15...where were you?").
Having a rover partner is very helpful with speeding up your set-up and take-down operations.
You can consider larger, more effective antennas if you have a crew of 2 installing things.
You will also find that you make less mistakes with a co-pilot participating in things with
you. A 2nd operator is extremely valuable with logging, as well. Sometimes we go to locations
where many guys are looking for us, and it's necessary to work them all quickly to keep everyone
happy. It's great to have one guy concentrating on logging, while the other guys works stations
at a rapid pace...not worrying about the paperwork.
Perhaps the best reason of all to consider dual-operator techniques is that of safety.
Especially on long expeditions, rovers get tired. Having a buddy along to talk with, and
discuss things is really helpful in staying awake. It's also a lot more fun to share
something that you enjoy with a like-minded person. 2 heads are definitely better than one.
....listen for the weak ones...73...de W3IY..........~~~~~~~