Saturday, March 25, 2017

Business Trips, or How I Learned to Stop Worrying and Love Semi-Duplex

2 weeks ago I was told I needed to fly to Milwaukee for  <insert corporate speak here> to do <insert more corporate stuff here>.  My travel plans and work schedule would allow for some downtime to go outside and explore the area, and while there are a few Satellite operators in the area, there were a few grids that needed some rover love too.  Plus it was a part of the country I'd never been to before with the arrow, and I'm always looking to expand my VUCC/R portfolio. A couple things I was thinking about before though.. I've been toying with a home based automated station since the trip to CM93. It's still got a lot of work to go, but it's more or less passable.. kinda... most of the time. Where I was staying for work was only about 90 minutes south of EN65, which is a grid that I (and quite a few others) needed. So how to go operate /P from that grid, with my equipment, and still have equipment at home running my remote station. Also since I would be flying, space would be at a premium and small multi-use equipment would be the order of the day. Also some power (to control the pileups) and all mode capability were a must. What to do..

The Home Station. It mostly Works. 

Well, first thing first - the 821 has to stay at home. Too big, plus it runs the remote station. So that leaves with with the 857 as my only other all mode rig. I've got a Funcube Dongle Pro+ I've used on occasion, but all the stuff to hook up to laptop and run power inverters in the car and a table to put the equipment is such is a pain, and not conducive to a guerrilla portable operation like I was needing to conduct. So after much soul searching (and a couple beers) I settled on the 857 solo. This was not an easy decision to make. In the 3ish years I've been a Satellite operator, I have never run half duplex. Even my very first contact on SO-50 I was full duplex on. I learned that full duplex was the way to be, and the semi-duplexers were lids that just jammed up the birds talking over others. Semi-Duplex operation is the devil and should be shunned. Well, now here I was getting ready to tip toe onto the dark side's playing field. Gee whiz, how things change.

First the build... how to make a mobile rig like the 857 portable. The most obvious solution is to hang it around your neck like the 817, but finding a way to attach it to myself would require some construction. After getting a tip from Matt, KK4FEM, he said that metal rulers ($2 a piece at Harbor freight) make great side mounts for the 857. After grabbing the rulers, finding the correct M6-4 screws, some hole punching and drilling, and liberating and old strap from a backpack, we were in business with the radio. Next I hacked up some small 5 ft RG8X jumpers (cause I've got a ton of that coax laying around) crimped on proper connectors to work with a Comet 4160 Diplexer I had, put my small 8400mah Zippy battery in the pocket of my hoody, connected the mess of cables together and to my spare arrow, and I became a fully contained pedestrian mobile ground station.

Building Tools, out of Tools
So, now to test. From what I understand the standard 'rule' for operating half duplex on FO29 is to find a quiet 10khz chunk of transponder or so AWAY from the center - In this case I went to 435.870 and scanned up and down 10khz to make sure it was clear. I then fixed my TX at 145.930 - figuring I'd come out at 870 +/- doppler. I then took an educated guess (as the bird was about 10° above the horizon) on a 60° TCA pass, figuring I should hear people responding to me about .878 or so. I also made sure to give a fairly long call and specifically say I was half duplex in my CQ call, asking for people to give me a long call in their reply, cause it would take me a second to tune them in. Right away I picked up KD8CAO, who did just what I had requested, giving me a nice long phonetic response allowing me to tune him in easily. We had a quick chat, with my TX remaining fixed on .930 and my doppler slowly dropping in frequency as the bird's relative speed to me changed. I picked up W5PFG and a few more, and called it a successful test. Alright, so this just might work afterall. I packed everything up, loaded up my suitcases, and went on with my week.

Fast forward a couple days and I'm on site in Milwaukee. I find myself on the EN63/53 with my setup. SO-50 is coming, I work the pass, hand out some grids. Not too bad. SO-50 is probably the easiest, and simultaneously the hardest of the birds to work half duplex, in my opinion. In theory you just fix your TX at 145.850, listen on the downlink, everyone is one spot. Piece of cake, right? Well, not so much.. Everyone and their dog is on SO-50 these days, and like any single channel repeater, everyone is talking over each other.. so without full duplex operation, you don't know if you're actually making it in. This is, obviously, problematic.. but it's not the end of the world. If you're in a rare spot, you can let some others do some work for you. Since they're wanting to talk to YOU - they'll keep at it until you answer them. This makes it a bit easier as the one being chased, versus the one doing the chasing. Also, be prepared to answer people a few times if they don't seem to 'hear' you when you respond, there's a good chance you're getting stepped on. Just the way of the world.

It's cold... and dark.. and cold. 
So SO-50 was working pretty well. The next night I tried an AO-85.. this is a little trickier, since you have to adjust the uplink instead of the downlink. Luckily I've worked it enough that I had a pretty good idea of what the doppler should look like, and managed to make a handful of contacts. AO-85 is also a much less busy bird than SO-50 is, and the operators that frequent it tend to have better skill. So, having a handful of passes under my belt, I upped my game a bit.

Peter, 2E0SQL is an AMSAT friend, and at the time was hunting his 100th grid for his VUCC. EN63 (where I was staying) would have been a new one for him. If you notice the callsign though, you know he's in the UK, and transatlantic passes are not exactly a piece of cake, let alone using something other than my 821, and a short arrow, and RG8X, and me being half-duplex. It would be a challenge to say the least, but that doesn't mean we weren't going to give it a shot anyway. So we found a pass that worked, decided on a frequency I would call CQ on, and then he would hunt me down and we'd try to make the contact. Luckily my hotel room was on the 3rd floor, and I had a balcony, and it was facing the proper direction for the bird. So even with alot of factors stacked against us, we had the Location factor on our side. All the stars aligned, and right at my AOS Saturday morning I started calling CQ and Peter found me and we had a very quick QSO at 6200km, with all the above caveats. Not too shabby. Even better, I found MI6GTY calling CQ a few khz below us, and by dumb luck managed to adjust my uplink close enough he was able to find me. So on a 3.2° TCA FO29 pass, with sub-optimal gear managed 2 transatlantic QSOs while still in my pajamas, on the balcony of my hotel room. That was pretty cool, I have to say.

Mountain or Building.. Still all about the Location.

I could keep going on for a while talking about this, but I drove around, made some more contacts, finished up my project, and came home. To tell you the specifics of everything would take multiple more entries, and I don't have that kind of time. I do want to mention specifically though meeting up with David, WN9Q who lives a bit north of where I was doing my work. I had some downtime between passes Saturday afternoon, and I stopped by to meet him for a bit while he was helping at a community Ice Rink. We attempted the world first Zamboni Mobile QSO, but didn't have much luck, being inside a building and all.. We chatted, swapped stories, and played around on the ice with heavy equipment and Arrows... all in all a great afternoon. David is a super cool guy, and it was good to meet him in the frozen north. 73 my friend.

Yes, I was twisting for polarity.

David, WN9Q and Dave, KG5CCI

I guess the point about all this I'm trying to make is, half duplex should not be your go-to method for working the birds. It felt really really weird skipping most of the mode B passes, and not hearing my own voice to know I was getting in and on frequency. I would not recommend anyone use semi-duplex for chasing folks either... unless you're the DX, no one is going to give you the slow calls that are required to switch around and make the QSO. Satellites are a fast and furious business, and you gotta be on the ball to be a good chaser. All this said, if you ARE the DX - and you know people are going to be looking for you, and you're in a situation, like I was, where you're strapped for space, time, and resources, and the only other alternative is simply not having a radio at all... semi-duplex will get the job done. Stick primarily to the mode J birds, fix your transmit, never key up unless you're hearing things first, let the chasers come to you, keeps things simple, and practice. Like every aspect of this hobby, there are lots of ways to get that contact made. Don't let you preconceived notions of how to do things hold you back. Embrace the new and the different. You might just surprise yourself. I know I sure did. 

Illinois State Beach on Lake Michigan. Looks nice, still cold.  

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