My activities on 1 GHz and up
(non - ATV)
* 1296MHz Narrow Band Activities
--- My Activities, Tranceiver, Transverter, Varactor Tripler and Antennae
* 2400MHz Narrow Band Activities
--- A Rebuild of the LMW 2400MHz transverter
* 10GHz NB and WB Activities
* Go here for my 24GHz NB Activities
* Go here for my 38GHz Commercial Xceiver
Over recent years I have been building up a collection of microwave equip. from 1 - 38 GHz, some of it commercial and some homebrew. The idea being to have a lot of different designs to choose from when wanting to construct a working system. E-bay has been a good source of ex-commercial NEC and Harris 5, 24 and 38 gig xceivers. Amateur radio club trash and treasure sales have also been a good source of parts like - Satellite LNC's etc that are reasonably easy to convert from their 12-14 gig to 10 gig to be used as low noise pre-amplifiers.
1296MHz activities
The 8th Sept.'07 was my first decent test on 1296MHz. It came as part of a weekend of microwave ATV activities inland from Sydney, between Mt Towac (near Mt Canobolas, Orange) and Mt Ginini, near Canberra. This was a distance of 241km a personal best for me, outstripping my previous best of 76km on a path along the NSW coast between Dobroyd Pnt and Wybung Head. I was using a varactor tripler from my 432MHz transmitter to produce approx. 6W on 1296MHz. This was fed to my 21 ele. yagi. For receive I was using an AOR2002 scanner on loan.
There were 2 sets of contacts for the day, firstly --- to Dave, VK2JDS who was NE of Orange and 40km from our location. Signals were ludicrously strong, 9+40 both ways. Dave was running ~ 20W into a 3m dish, and we could still hear his signal at 9+ even with no antenna in the AOR receiver.
The second path was to Bob, VK2MRP/P1 who was on Mt Ginini near Canberra, a 241km path. Signals both ways were 9+10-20 making it a very easy contact and leading me to realise that much greater distances on FM were possible ... looking forward to breaking the 500km barrier.
Above -- 1296MHz Yagi -- The boom is just on 2m long
In August 2009, I purchased an Alinco tri-band handheld 2m,70cm, and 23cm. An awesome bit of gear and finally gave me a way to start making 23cm operations a reality. I have 3 other op's within 6km of home that I have regular QSO's with. Peter, VK2HC, Compton, VK2HRX and Mick, VK2CMP. I found that pointing my 9 ele Yagi towards Compton and Mick, I can still work Peter off the side of it. The longest distance worked so far is 95km, Mt Gibraltar to Mobbs Lookout. Rubber duck antennae on both ends of the link, The same path as my first 10GHz QSO. The Alinco has a healthy 1 W output on 23cm.
The need for a bit more power also became obvious. Altho its suprising what can be done with 1W (see above comment) using the rubber duck antenna that came with the radio. I decided to finally put to use a Mitsubishi M57762 18W power module that I have had in storage for some years. During Jan and Feb of 2010, I put together an amp that the 1W from the handheld produces an easy 18Watts out.
Click for larger image
Below are a couple of pix of the 9 ele Yagi with measurements overlays for anyone who would like to copy it.
Above, an overall view of the Yagi
Above, a closeup view of the feedpoint
In April 2010, I purchased and built up a Kuhne 144-1296 transverter kit. It went together very well, 90% SMD components was a serious challenge for my aging eyesight haha. I have some interesting plans for the use of this xverter... to be reveiled once the project is finished. A front and back view of the completed xverter. It produces a good 400mW, in fact an easy 450mW, throttled back to make sure the 2 main TX devices dont work too hard. On the first pic below, the top right connector = 144MHz IF I/O centre connector = 1296MHz RX and the lower right connector = 1296MHz TX.
A few brief comments about varactor triplers .... 1) -- FM only; 2) --- They are around 50% efficient, ie. 10W in ~ 5W out. The BAY96 Varactor diode ( a popular one) can handle ~ 15-18W at 432MHz max. I personally wouldnt risk pushing it harder, the diodes are getting very hard to come by. 3) --- Don't forget, not only is your freq tripled, so is your FM deviation, only a quiet voice, almost a whisper is needed into the 70cm TX microphone.
Above 1296MHz Tripler photo; and to the right, click on thumb for cct diag. of tripler
Here's a couple of 1296 antenna ideas that I have played with in the past. The dipole was designed for use with a corner reflector. I based this scaled version on a design for 1500MHz and found that it worked well on 1296MHz.
2400MHz activities
Although I have been on 2400 MHz using ATV, I hadn't really considered getting active there using FM or SSB voice. That was until Jack, VK2TRF, gave me an inherited transverter system that he wasn't going to make use of. It had sat on the shelf at home for several months before I finally got around to having a closer look at it. After some calls for help about the circuit/project on the USA, WA1MBA microwave email forum, I discovered that it was of 1980's vintage and even got an email from the original designer, Chris G8LMW. PDF file data from him and hard copy files from Trevor, VK5NC.
Above is a pic of the transverter as I received it, mounted on a sheet of perspex. The left hand module is a 2-stage GaAsFET receive preamp. It feeds the top right module, a RX amp with LO injection for a 2m (144MHz) output. The large central module is the TX up converter unit. The right hand module is the LO board. I have removed the boards off the sheet backing and am cleaning up and retinning all the cct tracks many of them are very tarnised, bordering on corroded and the total resolder job ensures all the component connections are good, without dry joints.
Below is a 16 element yagi I purchased from the MFJ stand at Dayton hamfest in 2006 (US$28). The lower pic shows a closeup of the folded dipole feedpoint.
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Page created 26 Jan 2005
Modified 08 July 2008 (removed 10GHz into to its own page)
Updated 11 July 2010 (added new 1296MHz activities)
Dave VK2TDN
