Monday, August 24, 2020

Marine Mobile

Some of my fondest childhood memories are of camping out on the water in our family's big cabin cruiser.  My dad would bring along a Heathkit receiver that he built and while we relaxed and fished he would listen to interesting stuff like hams and marine HF-SSB ship-to-shore traffic.  I would marvel at the fact that we were on a boat out in the middle-of-nowhere in the Arctic and listening to cruise ship passengers phoning home from the Caribbean.

After languishing under a tarp at my dad's place for 20-odd years, the old boat eventually followed me home and in 2015 I did a complete restoration on it.  Ham radio was in the plan from day-one.  During the refit I made sure to install all of the antennas and cabling that would be required.  The HF antenna is a 19-foot long two-piece fiberglass vertical mounted on the gunwale with a counterpoise of 2-inch aluminum foil tape run along the inside of the hull right at the waterline.  On the roof I installed an MFJ-1436 tri-band whip for VHF/UHF and 6m.  I used the aluminum tape again under the fiberglass to form a suitable ground plane for the whip which I intended to use mostly for working satellites.  Summers up here are quite short and it was already August that year before the boat was finally ready to go in the water.  The installation of the radios had to wait until the next season.


Back on the water after all those years.

My plan for the radios got somewhat complicated.  What I really wanted was an SDR version of my venerable old Kenwood TS-2000.  My Kenwood was gathering dust, having fallen victim to the dreaded "ceramic filters failure", and there was nothing available in my price range that did 100-watt HF, full-duplex all-mode VHF/UHF for satellites, and was SDR-based.  The closest I could come up with back then was a Flex-1500 QRP radio with an HF amplifier and transverters and amplifiers for VHF/UHF.  I'd mount all the gear in a portable travel case and bring along my laptop to operate with.  To make it all work the way I wanted would take a lot of homebrewing.  The HF part was easy, or so I thought.  In the junk pile I had an old commercial HF transceiver.  I pulled the 100-watt amplifier off of it and added connectors and a T/R relay.  Since I planned to operate into a non-resonant antenna, I bought a cheap manual antenna tuner which would also take care of harmonic filtering.

The VHF/UHF part was even more complicated.  The little Flex radio had a separate transverter output so I built a pair of switchable transverters and brick amplifiers for each band.  Since I needed full duplex for satellites, I opted for a separate receiver using an RTL USB dongle built into the transverter box.  With everything bench tested in the shop and mounted on a plastic board in a carrying case I was ready to go.  Or at least I thought I was.  I took all the gear and put the VHF/UHF whip on my truck to see how it worked.  It didn't.  I couldn't seem to hear anything.  I pulled out my Arrow dual-band yagi and that seemed to receive ok but, despite my best efforts at shielding when I built the transverters, there was significant desense when I was transmitting on the opposite band.  I had a FunCube Pro SDR dongle which I pressed into service to replace the RTL stick (thereby bypassing the 10m IF chain) and it worked but obviously
some re-engineering was needed.  With the 2017 boating season fast approaching I decided to just focus on getting the HF setup going.

As I mentioned before, the summers here are short.  If time and weather cooperates I can
maybe get the boat in the water a dozen times between mid-June and Labour Day.  Over the next couple of summers I'd bring the radio case and the laptop out with me every once in a while but getting it to work on HF proved surprisingly frustrating.  The manual antenna tuner was very finicky and the laptop running the PowerSDR software would frequently lock up from RF on the USB cables before I could get the tuner adjusted.  I'd spend a half-hour or so and then give up until next time.  More ferrites.  Different cables.  Oops, the amp blew up, need another one.  Maybe an auto tuner?  Nope, won't tune with so many unattenuated harmonics.  Oops, blew up another amp. After the summer 2019 season I officially gave up.  That winter, I sold off the Flex radio and the auto tuner and decided to just fix up the old TS-2000 and use that.  A handful of new ceramic filters and a couple hours of delicate solder surgery was all it took.

With the repaired TS-2000 in the boat this summer, I got the HF working right away in June.  I had initially assumed that the auto tuner in the radio would be able to load the big fiberglass vertical but alas it would only tune up on 30m.  Before the next trip I put the old manual tuner from the previous iteration in and was then able to operate across the HF bands.  I also gave up on the big laptop and opted to use the Pipo X8 that was already mounted on the dash.  The little nav computer was a bit slow but would run WSJT-X without much difficulty.  I still wasn't having much luck with VHF/UHF though.  The MFJ antenna didn't seem to work at all.  After checking all the cables I started to think that there might be something wrong with the antenna itself.  Since by this time it was long out of warranty, I decided to just buy a new one.  At the same time, I also opted for another automatic antenna tuner.  The manual tuner did work but was still finicky and the longer this project dragged on the less patient I was becoming.  After scouring the marketplace I found that HRO in Anaheim had stock on both an MFJ-939 auto-tuner with the Kenwood cable AND a replacement antenna.  Being so close to everything finally getting sorted out, I also opted for express shipping.  Even here in the far north, Priority Express mail from the USA gets here in about a week.  HRO shipped them out the same day and I followed the tracking as the package passed through LAX and landed in Vancouver two days later.  Then, nothing.  No more tracking updates.  USPS said it arrived in Vancouver, Canada and Canada Post said it was waiting to receive it.  I thought maybe it fell off a truck or something!  After 21 agonizing days (yes, THREE WEEKS!) Canada Post finally received the package and sent it to clear customs.  It was out of customs the same day and arrived here a week later.  I have no idea what it was doing all that time at the airport in Vancouver but I did see anecdotal reports of mail backed up at the border for weeks on end so I was just happy to have it eventually arrive here intact.



The HF station mounted at the helm.  The radio on the left is a marine VHF.

I installed the new tuner right away (works great!) and a couple of weeks ago I got around to replacing the VHF/UHF antenna.  Unlike the HF (which only works on the water), I could do this part in the driveway.  Armed with my SWR meter, antenna analyzer, cables, and the HF/VHF/UHF triplexer, I pulled the boat out from under the carport and put up the new antenna.  After checking everything and hooking up all the cables and the triplexer, I made a satellite contact on AO-91.  After four years of monkeying around I finally had it all working!  I gathered up all of my tools and test gear, closed up the boat, and put it back under the carport awning, eagerly anticipating the next boat trip. 
I paused as I walked into the house and a sinking feeling came over me.  I went back outside to look and, sure enough, I forgot to fold over the antenna after I was done and broke it off backing under the carport. $@#%!^@#$!!!

Actually, this story does have a happy ending.  All that broke was the brass NMO mount and I was able to quickly rustle up a replacement and install it.  I loaded fresh Keplerian elements into Orbitron and set up WiSPDDE to handle the radio tuning.  In between fishing and relaxing last weekend I made over a dozen satellite contacts as we swung on the hook in a beautiful local lake.  Life is good!

1 comment:

Phil K6EID said...

great story. tnx for 17m qso
73
phil k6eid