Tuesday, June 19, 2012

Field Day preparations continue

A while ago (May 10) I wrote about Amateur Radio Field Day preparations for the Utah Amateur Radio Club (UARC.)  As with all such plans and organizations, things don't go exactly as one intends/hopes but if a bit of flexibility is built into the grand scheme, punching a few holes here or there isn't going to cause a disaster.

Last year's UARC Field Day came about the closest in recent memory to being a disaster.  Due to a bit of miscommunication, boxes showed up at the Field Day site - located some 2 hours south of Salt Lake City - that were not the ones containing important items such as radios, microphones, power supplies, etc. necessitating an early morning run (post-midnight departure from the site) back to where we store our gear with a return around 3-4 AM - and using about $80 in gas!

The next morning (Saturday, the first day of Field Day) we fired up the generator - an 8kW propane unit mounted on the trailer with our 85 foot tilt-up tower - and discovered that the motor tilt-up motor was seized.  Undoing a few screws on its housing, we let a pint or so of rusty water pour out of it and broke it loose, but it no longer hummed when we pushed the "UP" switch.  See the note at the end of this entry for a few words on what happened and the "fix."

Fortunately, this wasn't the motor that actually elevated the tower so 20-30 minutes of people trading off, manually turning the pulley brought the tower to an erected and locked position whereupon the elevation to its full height using the motor that did work could commence.

At noon - the time at which Field Day starts in these parts - we were still rummaging around madly finding bits and pieces to get the stations on the air and we didn't emit our first cycles of RF from our CW until just about 5 minutes or so after Field Day had started with the SSB station going a short time after that.

Fortunately, those were the majority of the difficulties that we had last year that would have seriously hampered our operation:  They say that disasters come in threes, and that count seemed about right last year!

If we had gone through all of that last year and hadn't learned anything I'd say that we'd deserve everything that fate would throw at us, but this year we made a conscious effort to avoid repetition of the more egregious of our mistakes.

Here are a few random comments on our planning this year:
  • A bit more careful planning.  This should be an obvious one, but its probably the most commonly overlooked point.  To a degree, it was assumed (there's that word!) that everyone knew more-or-less what to do.  Up to a point, this is fine - if everyone involved has done it before, but if one gets new blood in the group a bit of extra mentoring is a really good idea!
  • Go through the gear beforehand.  This isn't a problem unique to last year:  At the end of Field Day everything seems to get thrown into boxes and heaved into vehicle and then unloaded again for storage.  This is fine as long as someone makes sure that all of the gear gets back but it's often the case that it isn't until setup time next year that anyone actually looks in the boxes and discovers that things have been moved around and that critical pieces are where they are supposed to be.  What inevitably happens is that items have magically found their way into boxes that no-one thought bring the next year  ("Why are the microphones in the box with the TV twinlead - and why do we even have a box with TV twinlead, anyway?")  This year we made a special point of assembling all of the critical gear and putting it all together we well as throwing out junk that was not only useless, but a liability should it actually be used.
  • Occasionally rebuild things like antennas, feedlines and patch cords.  Over the years, our wire antennas have seemed to have mutated from simple (but effective!) wire dipoles to things fed with twisted-together ladder line that led to trap dipoles that had had their traps bypassed with wires.  This year, about all we saved of these old antennas were the longer pieces of ladder line and the insulators, sending much of the rest off to be recycled.  We also bought a case of one particular type of cord reel that seemed to do a better job of accommodating both the antenna and its feedline while being easier to use and have some hope of fitting into reasonable-sized storage boxes.
  • Prevent the antennas from just "happening."  Years ago, we decided on placing our two triband Yagis and towers in a north-south line allowing each station to point east or west (where the vast majority of QSOs will be found from our Utah location) and not at each other.  Being separated by several hundred feet, this allows good separation to keep the stations out of each others' receivers as well as tall mounting points between which our wire antennas may be run.  Last year - because it "happened" - we somehow ended up with our two lower-band (80/40) wire antennas end-to-end adjacent to each other on the main span between the towers which meant that we couldn't help but to clobber each other.  Worse, this wasn't "discovered" to be a problem until it was too dark/late (when 10/15/20 closed and 40/75/80 meters opened) to heave/shoot ropes into the trees and erect yet another wire.
  • The other sticking point was that we didn't seem to have enough "whole" pieces of ladder line hanging around to connect an antenna to its radio that might be 200 feet away.  Reluctantly, for one antenna we had to use coax, instead - particularly runs of RG-58 and "Mini-8."  Now on 40/80 meters with resonant antennas, the extra 2dB or so loss isn't a big deal, but these were not resonant antennas.  As noted above, we've rebuilt antennas with plenty of ladder line available.
  • On the above point, if you run non-resonant antennas and feed them with ladder line into a tuner that can handle the power (100 watts or so) you are pretty well off, but as mentioned above at least one of our antennas had to be force-fed with coax which can result in high losses if the antenna's nowhere near 50 ohms.  The other problem was that we seemed to have a dearth of tuners with baluns that could handle the power!  One of our members happened to have a 300 watt MFJ antenna with a balun, but we discovered to our chagrin that its capacitors would arc over at anything above 30 watts or so given the load that was presented at the feedline - so QSOs seemed to be rather hard-fought and sparse.  Not only did this mean that we had to run QRP on an SSB station on a noisy 75 meters, but the tuner's tuning didn't "feel" right.  It wasn't until very early in the morning (3-4 AM or) that the last CW operator hit the sack and I was able to steal a "good" tuner and realized that the MFJ was probably operating inefficiently as well!  Upon "tuner replacement" I was suddenly able to easily make QSOs!  This year, the club will be equipped with a "new" Heathkit tuner easily capable of 1.5kW (picked up at a swap meet and refurbished) and several members will (hopefully) bring along decent, large tuners of their own as well!
  • As noted on the May 10 entry I'd analyze the "hiss" that the club's radios (Kenwood TS-450's) emitted on the ham bands equal to and lower than that on which they were operating and determined that if one simply had the tuner engaged (even when running into a matched 50 ohm load such as the Yagi) the out-of-band noise would be reduced by 8-25 dB, depending on configuration while losing less than 1dB of transmit power.  Simply knowing this should allow us to operate our multiple HF stations simultaneously while managing the inevitable QRM that results to levels that will hopefully be of little consequence.  We've managed to do this in years past - probably a bit serendipitously - and we hope to do this again.  With our better equipment organization, we'll also have the potential of wielding some of our filters and stubs to further-reduce interactions between stations!
  • A bit better organization of the station operation itself.  One of the most important aspects of all of this is to expose hams (particularly new hams!) to the frenetic pace of Field Day activity - particularly on HF.  Considering that one of the main purposes of Field Day is to test our ability as hams to operate in a manner similar to that which might be encountered in an emergency situation, what better opportunity to give newly-minted hams, those who have not yet operated on HF or even non-hams a bit of mentored on-the-air experience?  One aspect of UARC's field-day operations has always been a bit of a more casual operational atmosphere where one can learn under less pressure that might be encountered in operations where the goal is the highest number of Q's (QSOs - or contacts) possible!  To an extent, we try to have several stations and/or times-of-day where all levels of operation can be accommodated and this year we'll take more care than in recent years.  Hopefully we'll also have more operators willing to keep more than one station on the air in the wee hours of the morning.
Every year things are similar, but they are also different - particularly since some previous attendees don't show up and that new people appear.  As with any organized, recurring activity it is always a challenge to "pass along knowledge" - particularly that of lessons learned but at the same time it's always good to have new people come along to gain new experience, bring along different (and sometimes better!) ideas!

After this year's Field Day I'll be sure to have a few additional comments on how things went - and what we'll want to do different next year!


P.S.  As it turns out, the elevation motor - which is mostly stainless steel - was none the worse for wear after the water was drained from it.  Even though it would not go up when called to do so, it did go down and in the later months we diagnosed a problem with the limit switch.  What had happened was that the jacket had shrunk away from the "SO" cord that connected to the switch and the combination of water, insects and the lack of a strain relief had caused one wire to become disconnected - the one that allowed it to go "up."  A re-dressing of the wire, cleaning of the switch and replacement of the ring lugs restored proper operation.

As for the motor itself, snow had settled on it over the previous winter and through condensation and gradual ingress, had filled the inside of the motor.  To prevent this from happening again a "hat" was made from galvanized sheet metal that prevented snow from accumulating on top of the motor while providing plenty of space for ventilation while avoiding yet another place in which hornets would build their nest!


This page stolen from ka7oei.blogspot.com

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