When I first started playing microwave a little over a year ago, I asked around about what bands I should get on first. I wasn’t sure which were more popular or what other factors might affect which band I should get on first. After some discussion, 10 GHz was one of the first bands I chose to get on. When I opened up the kit for 10 GHz and saw that part of the work involved using a blowtorch to sweat copper pipe onto a circuit board, I wondered what I had gotten myself into! I kept rereading the note that DEMI would take the kit back and build it for me if I didn’t mess it up first. But I figured hey, lots of other folks have built this kit, I can build it too. And I’ve always liked building kits – my mother informed me that on the way home from the hospital after I was born that Dad stopped at the Heathkit store on Ross Ave here in Dallas – and I’ve built a few myself over the years.
I built the kit and I can’t thank DEMI enough for making such high quality kits available for all of us. It really has been a boon to our niche of the hobby. I had great luck with my other transverters, but for whatever set of reasons I had trouble with my 10 GHz LO from the start. I blew up a couple of MMIC’s in the LO and in the LO chain on the main board. I’m still not sure how I did this. Even after I got the LO repaired, it would drift all over the place as if it wasn’t even crystal controlled. While I was exploring options on fixing this, Bob Gormley, WA5YWC, suggested that I look into AD6IW’s phase-locked LO which was designed to produce a number of different frequencies from 1-1.4 GHz by setting a dip switch. The idea of being on channel and eliminating one more variable from the list was very appealing.
Just before the new year I bit the bullet and ordered one of the PLO’s. Goran, KD6IW, was terrific and set it up for 1136 MHz and the right power level for my 10 GHz transverter and sent it on its way. When I received the PLO, just after the new year, I put it on the bench, powered it up and hooked it up to my frequency counter (an HP 5342A). It was within 100 Hz from the start. Over the next week I tweaked it as it aged and at the end of the week, it was within 20 Hz all of the time.
I had originally setup my 10 GHz rig with a long IF, power and PTT cable that could be run from the truck out to a DSS dish I had setup. The cable was about ten feet long and had two power wires, a PTT and a very thin coax run for the IF. With the PLO, I realized I could run one more coax run along this path and put the PLO in the truck away from the elements. I reasoned that this would keep it that much more stable. The transverter would be in the elements on the back of the dish, but would have no oscillators in it to drift! I put a run of ten feet of thin coax between the frequency counter and the PLO and upped the power in the PLO so that it easily overcame the loss in the run of coax with +3 dBm at the counter. I drilled a hole and mounted an SMA connector in the 10 GHz transverter and removed the MICROLO – I was ready for contesting!
For the contest I also put the PLO in an old DigiKey shipping box and put Styrofoam around it to give it some additional thermal isolation. I also mounted the omni slot antenna that was a joint venture between Harold, K5SXK, Craig, KA5BOU and myself up on the truck. After picking up a run of ten feet of superflex from Ted at TESCO with about 1.5 dB loss, I was set for omni while driving on 10 GHz.
I was pleasantly surprised that the LO stayed on frequency (I did hunt around for people, not having had enough experience with the LO yet and after searching I found W5LUA right at 10368.100). We’d like to make the AD6IW PLO a club project for those interested. Please contact Bob Gormley, WA5YWC, at bob.gormley@earthlink.net or in person if you have an interest in this project. The LO will work for a number of different bands, not just 10 GHz.
I was delighted to work W5LUA, WW2R, and NM5M while mobile. I even got to hear my first rain scatter which I’m sure many of you have heard, but this was a first for me. Dave commented that he wished he had recorded our QSO which had Doppler from driving and rain scatter components at the same time. While I’ll probably never break any distance records on an omnidirectional antenna, it was thrilling to operate on it and I’m delighted with the performance it has. 10 GHz has gone from the band I was having trouble with to one of my favorite bands!
I mentioned in the last meeting that there are three models of Motorola 900 MHz amplifier that are available from a couple of people on eBay that produce 150, 300 and 600W. I have converted the 150 and 300 W versions. They have been available for $50-400 on eBay varying on the model and the timing. If this is a project you are interested in, let me know and we’ll try to arrange a group purchase of several amplifiers and I can do a presentation on how to convert them.
Steve