Run 'n' Gun "Roving", Paul Goble (ND2X)
"Roving" is mobile microwave operations from a vehicle, and all the pecularities that
line-of-sight communications brings with it. This is in contrast to portable
work that operates microwave from a fixed field site. From Paul's considerable
commitment to roving, he has come up with a list of issues to consider while
planning your op. (BTW, "rovering" is something else, maybe that dog can hunt.)
The line-of-sight aspect of mobile microwave operations can be fun, but brings
with it a number of issues not faced by VHF/UHF operators. This article is
a synopsis of my experience with roving. One thing for sure is that there
are lots of little things that can go wrong, but some planning ahead can
make roving an enjoyable and exciting experience.
I have put together a summary list of things that I have encountered on along
the way. It is a good checklist to go through before starting your first
Equipment should suit your operating style.
- GPS is absolute "must have" (Garmin units do 6-digit maidenhead grid location).
- Four roving functions - drive, navigate, operate, log (note "drive" is #1 - HI!).
- I prefer to drive and operate with someone else logging and navigating.
- The 35-grid effort was operating and logging separate from driving and navigating.
- Current rules allow only two operators for any given rover including the driver.
- I've asked the current "committee" reviewing such things to reconsider based on safety.
- I've also asked that roving be broken out between "Run 'n' Gun" and the portable guys…….
- Minimize use of transverters as much as possible.
- TS-2000X best thing going right now (Jan '04) with 6M, 2M, 70cM, 23cM.
- Simplify your transverter situation as much as possible.
- Use one IF radio for many xvrtrs.
- Use single-band, stand-alone, pre-adjusted IF radio-xvrtr combos.
- When using single IF radio, require no adjustments when switching bands.
- Any req't to adjust IF radio when switching amongst xvrtr chains WILL blow something up.
- Each xvrtr chain must be adjusted to take single IF radio output/input/PTT.
- Nothing wrong with OEM power wiring which came with radio (fusing, etc).
- Nothing wrong with stock mics, but external speakers often help.
- "Headsets" can be useful if one will work with ALL equipment installed.
- It's rare that all shouldn't be able to hear rcv as well as xmt (esp. a logger).
- BACKUP!! Redundancy is the one truly pre-emptive anti-Murphy measure.
- Carry backup for as much radio gear as possible (fuses, mics, etc., as well).
- Backup antennas, cables, adapters and other accessories just as important.
Use KISS (Keep It Simple, I'm Stupid) to create your mobile.
- Be careful of adding "operating desks or surfaces" to your vehicle.
- It doesn't take much to cut a human body in half - it's scary!.
- If you add a table in front of an existing seat, add full-up NASCAR 4-point harness.
- All equipment must be secured in place (flying equipment kills).
- Ideally, nobody is in front of any gear which is not BOLTED, SECURELY, in place.
- Equipment can be strapped down if secure enough in the right LOCATION.
- It's not necessary to modify the automotive electrical system.
- "size" your electrical load to stay within it's capabilities.
- You're not gonna transmit two high-power bands simultaneously.
- You're never gonna operate without the engine running, anyway.
- Plymouth Acclaim - 90A alternator, 1 battery, 400W no problem.
- F-350 Diesel - 130A alternator, 2 batteries, 400W less problem.
- Run BIG, stranded copper from both sides of the battery to the equipment.
- Fuse the positive side (I do 100+A) CLOSE TO THE BATTERY!!.
- Under 10 ft, could probably get away with as small as #4 AWG.
- For 14 ft, I run #1 AWG.
- Welder's cable is ideal due to flexibility and VERY durable sheathing.
- Use master battery cutoff switch for safety.
- If something shorts and the 100A fuse doesn't blow…..
- Once lost a PA to oscillation because it was hardwired to power.
- Use one power distribution "block" for radios (etc.) & another for PAs.
- A fused junction block is a good approach for radios + multi-cigar lighter ports.
- Multiple "cigar lighter" ports available from rad-shack for GPS, laptops, etc.
- A welder's cable connector junction makes an excellent disconnect for PA circuit.
- Do not overly integrate equipment.
- Complexity encourages Murphy.
- Carefully evaluate functions - which things, if integrated, will actually help.
- Thorough testing + as much use ahead of time to debug is necessity.
- Bandswitching could be a simplifying "integration".
- If equipment supports external control.
- DON'T FORCE IT!!.
Working the Disadvantages
Remember you're at a disadvantage in a "Run 'n' Gun" situation.
- One is constrained to omni antennas.
- It is simply impractical to try to point directional antennas while moving.
- GPS/laptop/antenna AZ drive to point directional antennas exists, but software doesn't.
- Even if software existed, how to enter distant end data is not clearly defined.
- So, stack as much as possible, but there ARE limits.
- Vertical space required - see 220 & 432 MHz arrays on "red".
- Slotted waveguide vertical beamwidth limits to 10-12 slot pairs.
- Run RG-214 or better (depending on band) to keep line losses down.
- Higher the frequency, "bigger" and shorter the cable.
- 3/4" holes won't take "N" connectors.
- Run as much power as you can muster; +4dB (from 150 to 400W) was astounding.
- Leading limitation I've encountered is man-made electrical noise.
- Use antennas with as little vertical response as possible.
- DSP in radios can help if signal is strong enough, but only real sol'n is driving away.
- If your radio has enough audio output, the Clearspeech NR speaker is amazing!.
- SECOND Leading limitation I've encountered is physical masking.
- Just over brow of hill from distant station.
- Those "hilltop cutouts" where they cut a gully out of the hill for the road.
- Rolling terrain (like on I-35 So of Austin, or I-10 around Kerrville) & trees.
Plan... with a Map
Don’t even THINK of going out without extensive map study.
- I find the DeLorme Topo to be most useful.
- Some find DeLorme Street Atlas more to their liking.
- Grid lines a must!.
- To maximize number of grids, minimize E-W travel, maximize N-S.
- Pick routes along grid dividing lines as much as possible.
- 35-grid effort had ONE E-W path (EN28-EN18-EN17-EN08) along 48 deg lat line.
- I-29 is right along 96 deg lon.
- Dodge in and out of grids near primary route of travel.
- Determine general area for 2300 - 0700 period of travel.
- Research hams with desired bands who can hear/be heard within this area.
- Various email reflectors can be very useful for this.
- CSVHFS & RMG members are a great resource (or whatever organization covers "this" area).
- Bribe them to stay up during above hours to provide Qs within this area.
- Publicize route of travel via whatever means gets the word out.
- Research hams who live "anywhere" along the route and contact them individually.
- Having folks watch for you is a big help.
Liaison frequency is important - try to pre-arrange one not on a calling frequency
- Do this as part of the contact program research above which is to ensure folks will be on.
- The 35-grid effort was "assigned" 144.185MHz up north and we used it all along.
- Doesn't preclude calling on a calling frequency, but facilitates "..listening down 15".
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