Monday, July 23, 2012

QRP CW on the trail in the Wind River mountains of Wyoming

Over this past week I got the chance to do something that I haven't been able to much recently:  Run QRP HF from the trail while backpacking.   This trip was a 5-day backpack treck in the Wind River mountain range of Wyoming (near-ish Pinedale) with the vast majority of it being above 10,000 feet (3000 meter) elevation.

Unfortunately, I didn't get a chance to operate as much as I'd wished:  There's something about being tired after carrying a 50+ lb (23kg) full-frame backpack full of everything you need to survive for 8 miles (over 12km) each day at such a high altitude that sometimes makes you want to just lay down for the evening rather than run around finding trees and rocks suitable for stringing an antenna!

As it turned out, only 2 QSOs were made on the trip - and at least some of this "minimalist" result was due to the fact that the HF bands seemed to be badly disturbed due to high solar activity:  Only 40 meters seemed to be remotely usable during the times I could operate (approximately 6-8pm local time).
Figure 1: 
The ATS-3A (lower-left) and its band modules (top).  In the lower-
right is a modified Hendricks Altoids (tm) longwire tuner.
Click on the image for a larger version.

The station was fairly simple:  A Sprint ATS-3A (see an EHam review of this series of rigs here) running into a modified Hendricks Altoids Longwire (end-fed) tuner and using about 60 feet (18 meters) of end-fed wire with a similarly-long counterpoise running in the opposite direction.  The power source was a block of 8-10 AA cells (a mix of NiMH and a pair of "dead" alkaline cells from the GPS receiver) yielding a 9-13 volt DC source allowing the transmitter to produce between 2 and 4 watts.

As it turns out I could hear something on about every band that I tried (40, 30 and 20) but on all but 40 meters signals were extremely weak - even though I could hear an obvious difference in the background (atmospheric) noise on any band when I connected/disconnected my antenna!  On the two occasions that I was able to get on the air, 40 meters sounded rather "odd" - very rapid fluttering and a "hollow" sound often associate with auroral disturbances.

Figure 2: 
The carrying bag with the entire multi-band HF station,
sans power source and antenna wire.  A "nerd knife"
is shown for size comparison.
Click on the image for a larger version.
In tuning around on 40 meters I heard more than one instance of the CW note of the station being received being "split" into two separate CW notes a few Hz or 10's of Hz apart:  In many instances, the CW signals were so badly distorted that I wasn't able to make much sens of them - except during the brief periods when the distortion relented and the signal momentarily "cleaned up".  It was in those instances that running, say, 7-10 WPM would have been required instead 15-18 WPM that I was hearing!

Perhaps the weakest link of the QRP station was the antenna.  While I had a total of 120 feet of wire to spread out, it was rather difficult to find somewhere to sling that much wire, get it up a reasonable height into the air and still place it somewhere convenient to the operation station!  Being that the entire station was to be as lightweight as possible (since I was carrying it!) I had to forgo things like coax, so the antenna and counterpoise wire pretty much had to end where the tuner and CW transceiver was located:  Being that we were swarmed by bloodthirsty mosquitoes and deer flies it was most advantageous to operate from within the tent - yet another restriction on where our antenna wire could run!

For the most part the antenna consisted of the 60-ish feet of wire suspended only 6-16 feet (2-5 meters) above the ground since there never seemed to be conveniently-located cliffs nearby nor very tall trees just above our heads where we camped - which was pretty much at or above the tree line!  The best we could do was to either sling the wire across a slight gully or run it up the hillside, paralleling the ground, and tie the far end to the rather short trees found at those altitudes.

As for the QRP gear itself, it worked pretty well:  The Sprint ATS-3A (by Steve Weber, KD1JV) worked flawlessly - as did the tuner.  Connected to the radio instead of earphones so that both of us (the other party being Brett, N7KG - whose callsign we used for one of the QSOs) could hear the audio was a modified Radio Shack amplified speaker.  For CW keying I used my homebrew, lightweight portable paddles - easy enough to use at 12-15 WPM, but rather clumsy at speeds higher than this.

Figure 3:
The environs of one of the night's QRP operations in the Wind River range of Wyoming.
Click on the image for a larger version.

For power on the trip I brought along a folding 12 watt solar panel and with this I charged both camera and HT batteries and once those devices were charged I reconfigured things to top off the NiMH AA cells as appropriate.  I'd started out with 10 fully-charged AA cells, but as my GPS receiver ran down a pair, these would be swapped into the 10-cell holder.  For charging the depleted cells I would pop out the remaining fully-charged AA cells and jumper the empty positions with a clip lead to prevent their overcharging.

As it turned out the 12 watt folding panel was almost adequate for the needs:  At best we had only 2-3 hours of sun when we arrived at camp in the evening and another hour or two of sun in the morning before departing, not leaving too much time to top everything off!  Had I been out another 4-5 days, I'd have to have rationed power, but this situation could have been improved had I been able to devise some sort of "MPP" (Maximum Power Point) "switching" type charger for the panel rather than simple, inefficient brute-force charging which amounted to either dumping 12-15 volts into a linear 5-volt regulator for USB-type charging devices (my HT, for example) or simply shunting across the panel to top off the AA cells!  Had I some sort of efficient energy conversion system I could have likely doubled my overall charging power efficiency!


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