My 10GHz QSO Log

WBFM and NB Activities
Newest entries are at the bottom of the page (ie. chronological ascending from top down)
22 June, 2008
Sunday 22nd June '08 saw my first QSO on 10GHz SSB. I am so pleased, it has been a long time in the construction and planning. The distance of 95km from Mobbs Hill Lookout, Carlingford (inner west Sydney) QF56mf to Mt Gibraltar QF55fm, SW of Sydney. It is a line of sight path. VK1BL, Ted at Mt Gibraltar was using a DEMI transverter with a 3W amp (it wasnt needed) into a 700x 600 (round figs) offset dish. I was also using a DEMI xverter but with no amp. (20mW TX out) and initially an offset dish then moved to Jack's (VK2TRF) pennyfed prime focus 60cm dish.
VK1BL 's signal was just so, so strong, whilst disconnecting the UT141 coax from the horn feeding the offset dish, I could still receive Ted's signal easily with no antenna connected to the coax !!!!! amazing! a tribute to both the power Ted was transmitting and the hot receiver in my DEMI transverter.
Moving the transverter to the prime focus dish, Ted gave me a 59+ signal and I gave him a 59+++ he was right off the end of the scale. With a 20dB attenuator in the path of my sys brought Ted's received signal down to a managable 5x9+20 or so and my signal down to a 5x4-5. The 20dB atten brought my TX level down to 0.2mW at the antenna.
I am looking forward to increasing the path distance and improving my offset dish feed which was far from optimum as demonstrated when we moved to the second dish. At Ted's end of the link helping out was Owen, VK1OD and at my end Jack VK2TRF, my regular "partner in crime" haha when it comes to uWave hilltopping activities.

Click on images above for full size pics
Left - The 2 dishes; Centre - Me transmitting on Jack's dish; Right - Ted and his setup at Mt Gibraltar

Dave, VK2TDN

12 July, 2008
Dave, VK2CQ came over home to help me out with a WBFM experiment. I wanted to try the Gunn Osc. transmitter out
over a distance greater than across the room. We went out onto my street and Dave took the Satellite LNC and scanning RX whilst I proceeded to walk down the street and talk to him using the Gunn TX. The Gunn had a 18dB gain horn on it and the LNC was straight out of the box, ie. no additional antenna.
It was a great success as my signal could easily be heard over the 200m+ that we got between us. It was interesting to experiment with the reflections off cars moving up and down the street between us and also off the various buildings.

Dave, VK2TDN

08 Nov, 2008
Saturday 8th November '08. Jack, VK2TRF and myself did some short hop hilltop experiments.There were several objectives for the days' outting. Firstly Jack had taken delivery of his 10gig xverter from Khune (DB6NT) and wanted to test it onair. The Spring Field-day was the coming weekend and we both wanted to make sure all gear was working ok. Finally, we wanted to do some trials with different antennae and insersion of attenuators in the feedline to the antenna and see what it took to loose the signal at the receiving station.
Since the June test with VK1BL, I removed the 18dB gain feedhorn from the offset dish and replaced it with a modified LNC.
Removing the cct board and the 12GHz probes from the metalwork, I made a probe using a long pinned SMA bulkhead socket. The length of the probe (6mm) is an ideal monopole probe for 10.3 GHz. This came about after talking to a couple of USA 10gig'ers and seeing some of their pics of horn feeds. The conclusion was that my higher gain hornfeed was under-illuminating the dish and significantly reducing its efficiency.

Now for the tests, we started with 17-18dB gain horns at each end, Jack with 40mW and me with 20mW. The path was 23km (18.75 miles for the non-metric amongst us ;) ) line of sight path with a freespace pathloss of 140.0 dB. .....
Ohhh just a side note on freespace pathloss, basic formula is ....
log distance (km) x 20 + 112.7 = loss in dB ... 112.7dB = loss for 1 km, add 6dB loss each time path doubles
example ... log 23 = 1.3617 x 20 = 27.234 + 112.7 = 139.9 dB (140.0)
23km = 140dB loss; 46km = 146dB loss; 92km = 152dB loss; 184km = 158dB loss .... etc

The FM signals between us were full scale and starting with that, Jack added 10dB of attenuation in the antenna line which dropped the received signal to just below full scale. Skipping 20dB and going to 30dB of attenuation dropped the signal to ~ half scale (~ S5) and still a good readable copy. With 40dB of attenuation the signal became unreadable on FM. We both switched to SSB and although there was no signal strength, Jack's signal was quite readable. Finally, going to 50dB lost the signal totally.
Jack removed all the attenuators and restored full signal strength. I removed my horn antenna and was suprised to find that I could still hear a signal from Jack. I touched the centre pin of the SMA plug with a small screwdriver and he became virtually full quietening. He went to 200mW output and I could easily read his audio without touching the SMA connector, and touching it with my finger made his signal full quietening!!
I next tried a 400mm (18") dish with a penny feed, should be ~ 25dB gain, and Jack's 40mW signal was as expected better than the 18dB horn ... nice to know the dish was working!. We both then switched to larger dish antennae, Jack used his pennyfed 2ft dish and I used my 700x600mm offset fed dish. He then proceded to once again insert attenuation into the transmission line with 40mW of output. This time he was still quite readable with 50dB of attenuation inline and his signal was finally lost at 60dB of
insertion loss !!. 40mW (16dBm) - 50dB = 0.4uW (-34dBm) WOW

Click for larger image
The pic above shows the xverter mounted near the feedpoint of the dish which keeps the losses
in the UT141 feedline to a minimum. On the back of the dish is the Icom IC290H 2m allmode
xceiver that I have modified to give 8VDC up the coax for the xverter switching

Dave, VK2TDN

15 Nov, 2008
I am pleased to report that my trip to Mt Canobolas for the spring fieldday was a success. Mainly referring to the extension of my 10GHz SSB distance to 216km from Mt Canobolas to Mt Coree. Thanks Ted, VK1BL for having a 10gig station active. Once the dishes at each end were aligned Ted's signal was very strong at 5 x S8-S9+10. He has 3W into a ~ 35dB gain offset dish. My signal to him was a 5 x 2 with my 20mW into a ~35dB gain offset dish.

Whilst on Canobolas, I did beam east to listen for a possible scatter signal from Jack, VK2TRF who was beaming west from Top Ryde with 5W and a 33dB gain dish. Unfortunately nothing heard. Maybe the huge amounts of cloud and rain over the Blue Mtns between us did too much scattering.

Time to complete my 1.2 W and 3W amplifiers and then see how far we have to travel to find a 300 + km path that is pretty much LOS. Could be difficult!!. The other goal for this summer is 10gig rain scatter between Sydney and Canberra .. roll on the BIG thunderstorm cells half way between us.
Click for larger images
Left to right... Dish, Front view; Xverter and feed closeup; Dish, side view; View towards Mt Coree, 216km that way

The 2 other radios in the back of the car, a FT90 FM dual band for working repeaters and a FT897D for 2m and 70cm SSB

Dave, VK2TDN

14 Mar, 2009
A John Moyle Field Day outing
The opportunity was taken to activate 10GHz. Jack VK2TRF went up to Mt. Tomah in the Blue Mts, QF56FL ~1060masl. I stationed myself at Round Corner in the Dural area QF56MH, 214 masl. The distance between us of 53 km and was Line of Sight (LOS). Jack had 5W into a ~20dB ~25cm dish being held out of the window of his vehicle by Dave, VK2FDIW ... weather conditions were pretty bad at times on Mt. Tomah, with regular heavy rain showers passing through.

Jacks signal was 5x9+40 very very strong. My signal to him with my 20mW into a 35dB gain offset dish was 5x5. After the end of the first time block at 1500hrs, Jack moved down to a lower location where a group from the HADARC club had a multiband/op station set up. Jack was now beaming through wet trees and my signal had dropped to 5x0 still easily readable and Jack was still 5x9+20 or so. A good afternoon exercise and nice to know the gear still works :)

Left - my setup for the day; Right - VK2FDIW - Dave pointing the small dish in my direction

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Dave, VK2TDN

2 Apr, 2009
Finally a working 10GHz amplifier
After some serious experimenting with one design of amplifier layout for the FMM5061VF GaAs MMIC that was not totally successful. I put it aside for a while to contemplate some better grounding and other improvement modifications. To still get an amplifier working relatively quickly, I got an unbuild DEMI kit (minus the MMIC) from Ted, VK1BL. Building this kit was pretty straight forward and after the several initial voltage tests, I fed the unit with 16mW (+12dBm) from a DRO unit out of an old Satellite LNB (Front - Rear views).
Just as an aside....
This little unit makes a great signal generator. It comes out of an older and quite large LNB ( can't remember the brand offhand ). Unlike the modern LNB's that are very small and the DRO circuit is usually an intergral part of the main cct board this older unit has a totally separate DRO unit. Ohhhh --- DRO ???? you say .... Dielectric Resonant Oscillator do a google search to learn a bit about their operation. This one I retuned from 11.3GHz down to ~ 10.8GHz and soldered a SMA connector onto it for ease of use.
The DEMI 3cm 3W amplifier kit is another awesome product from this company that have a great range of kits and ready built amplifiers (TX and RX), transverters, other products and parts. This amplifier is based around the Eudyna FMM5061VF GaAs MMIC. Click here to get the datasheet pdf file. The MMIC covers from 9.5 - 13.3 GHz. It is a 3 stage GaAsFET amplifier with internal matching for 50 Ohm input and output, negating the need for impedance matching striplines, making it a breeze to use. Power requirements are a -5VDC at ~25mA for the Gate bias and a 6 to 7VDC at ~ 2 Amps on the Drain.

The DEMI ... Down East Microwave 3cm 3W amplifier
Left - Closeup inside view; Right - Overall view

Click for larger images
Dave, VK2TDN

19 Apr, 2009
10 GHz WBFM Fun
On sunday last (19th Apr) Paul, VK2EPH, came over home and we had a play with some 10gig Gunn Osc units that had a former life as a motion detector for a door opener. A circuit for the basic FM transmitter can be seen on my www page here.
A simple 1 transistor mic amplifier and a 555 timer for a ~ 1kHz tone generator. Either of these audio signals are used to modulate the regulated power supply to the Gunn Diode. The slightly varying DC voltage produces an FM 'ing of the 10gig carrier. Most of the Gunn Osc units produce output power in the 5 to 10mW range.

For receive we are both using satellite LNC's with a LO of 10.7GHz. These ones have the advantage over the ones with a 11.3GHz LO in that the I.F. signal comes out in the 300-400MHz area. That is within the range of many/most new and slightly older sanning receivers or even many modern tranceivers with wide band receive capability. The ONLY requirement is that the receiver is capable of WBFM and have vfo stepping down to ~ 12.5 or 25 kHz. The WBFM capability at >300MHz is where most of the slightly/much older scanners fail. Many of them only having WBFM in the 88-108 MHz band. I am using an AOR 8200 Mk3 scanner and Paul is using a TV antenna alignment receiver. After a few hiccups with faulty cables, batteries going flat etc etc we finally got a 2 way 10gig signal along my street. The cool thing was that it was full duplex, like talking on a phone both stations can talk at the same time. This was achieved by having our transmitters on slightly different freqs.

Over the short distance we were transmitting, Paul was using an offset satellite dish (need to get a pic from him) and I was just holding my sys in my arms, a 17dB horn on the Gunn Osc for TX and the satellite LNC on its own without any additional gain antenna. Paul and I have built DC inserters so that we can feed 12 volts up the coax to the LNC without it feeding back into the receiver.
Altho I have done and am still pushing my personal records on 10gig SSB. This was the first 2 way QSO on WBFM, till now they had all been one way with 2m talkback. Just need to get Dave VK2CQ's WBFM sys running so he can join in the fun.

Dave, VK2TDN

4 - 5 June, 2009
Transverter Upgrade
Just in time for tomorro's planned activity, I removed the crystal based LO/ multiplier to 1136MHz with a N5AC PLL/Synth board that had just arrived from DEMI on the Wednesday. The Friday outting described below was its maiden test. This turned out to be good and bad .... good ... I now had freq stability instead of wandering anything up to 25kc with temp changes.
Bad in that there was a ~ 1kHz tone present on my transmitted signal and on the received signal. At the time I couldn't prove that it was the synth board ...only suspected it as had never heard the prob. on the old LO board. Later on at home, I listened to the 1136 MHz signal on my scanner and confirmed that the tone was present. I also found that adjusting the tuning of the 10MHz TCXO changed the freq of the tone. On Sat 6th, June I experimented with changing the 10MHz TCXO. This appeared to have been an improvement, but need an on-air test to confirm.

Dave, VK2TDN

Fri, 5 June, 2009
Bouncing Off Buildings
Today Jack VK2TRF and I finally achieved a goal we had been wanting to try for some time. That is to reflect our signals off the Sydney CBD buildings. Dave VK2CQ joined me at my end of the link and in the photo's below you can see him at the mic. This was his first time operating on 10GHz. The weather was good... calm and sunny... a far cry from conditions over the previous week. Jack and I were operatings our standard gear as well described above ... him 5w and dish, me 20mW and dish.
My location was close to Top Ryde in a street where I could see the CBD buildings. Jack was at a park on Sailor's Bay Rd Northbridge area Nth Sydney, close to his home. Jack's path to the CBD was 6 km and mine, 12km. After setting up and peaking signals on FM, I got Jack at full scale (S9+++) and full quietening and Jack got me just above the noise. Moving to SSB improved my S/N ratio. Jack then travelled into the city to Centennial Park, finding a place to be able to park he fired towards the hi-rise buildings 1-2 km from him and he was just so strong into my location and my signal to him was also a bit better than from his earlier location.
Swinging the dish around proved that the signals from him were indeed coming via the CBD buildings. From my 12km distance, my 2-3 deg beamwidth was illuminating the entire CBD. These were both VERY non - LOS paths. This really proves that we don't need repeaters on 10GHz, everyone just needs to beam towards a bunch of hi-rise buildings and go for broke. If you are within 15km of the buildings and have ~ 100mW you are virtually garanteed excellent signals on FM or SSB. If you have more power available then you will be able to extend your distance from the buildings considerably.

Left - VK2CQ, Dave at the Mic; Centre - Looking towards the CBD; Right - side on view

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Dave, VK2TDN

Mon, 8 June, 2009
Bouncing Off Buildings, Day 2
Jack and I were at it again today, 10GHz has never been running so hot in Sydney :)
This time I drove down to the southern Sydney suburb of Sylvania to the home of VK2KON. He has a wonderful balcony view facing to the north. Jack initially went to his Northbridge location in Nth Sydney. A line on the map went to the west of the Sydney CBD and over the Nth Sydney CBD signals were easy between us.
Jack then went down into Greenwich in the Nth Sydney area where he could view the Optus building to his north. It was the only hi-rise he could see from that location. There was still good signals between us. He then beamed to the ~ south towards my location, his signal being reflected off the Sydey CBD buildings and still good signals. We did most of this on NBFM, sigs were so good there was no need for SSB use. This was Con's first time on 10GHz and he was impressed with the fun and abilities of 10gig. Hopefully another uWave convert in the making ;) We did try some aircraft scatter but not successful this time. Another great day out !!

Left - VK2KON, Con; Centre Left - Con and I ; Centre Right - Looking towards the CBD; Right - Jack's setup, Northbridge

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Dave, VK2TDN

Sat, 8 Aug, 2009
A New Callsign in the log on 10GHz... YES!! :)
Over the last 2 weeks Dan has been busy casing up his newly arrived Khune 10Ghz xverter along with a DEM 2.5W amplifier. We both planned this test outting about a week in advance and the weather was kind to us on the day. Dan and I used the usual coast path that has been used a number of times with Dan, Jack and myself for many ATV tests over the last few years. Dan went to Wybung Head on the coast out east of Morisset and I went to Dobroyd Pnt that overlooks Manly Vale, Manly and the harbour entrance. The path distance is 76km and is mainly over water.
See the red path plot on this map Our path was the same as the red 24GHz path. Dan fired up his "Freakin Beacon" and I instantly heard it at full scale on the "guess meter" ;) We dabbled with some added attenuation, I went up to 20dB of inserted atten. on my +13dBm of TX power before Dan virtually lost my FM signal. We chatted for upwards of 30 minutes before calling it a day. Thanks Dan for an enjoyable contact :) Another good day out

Left - VK2GG, Dan's setup at Wybung Head; Right - Me at Dobroyd Pnt

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Dave, VK2TDN

Fri, 02 Oct, 2009
Some Sea Path Experiments
Some weeks ago, Jack, VK2TRF and Dan, VK2GG did a 50km sea path hop along the central coast of NSW. This was a great success with very strong signals. This good result urged the 3 of us to seek out longer paths to see what distances may be possible. The test sites we decided on were for Dan to go north to Anna Bay. Jack to go south to the Shellharbour headland and for me to go to a site in between, near the north headland entrance of Botany Bay at La Perouse.

Paul, VK2GX joined me at my location, it was his first serious 10gig outing. Paul informed us that he has made the move and has ordered a DEMI 10gig xverter with built-in 3W amplifier YES!!!, another station on the band soon.

There was 154.6km between Dan and I, 75km between Jack and I and finally 228.25km between Jack and Dan.

Gear used, Dan - DB6NT xverter and 3W DEMI amp and prime focus dish, Jack - DB6NT xverter and 5W amp and prime focus dish (see pix of their gear in above and below log reports). I was using my DEMI xverter and 3W amp and offset 700x600mm dish.

Left 2 x pix - VK2TRF, Jack's setup at Shell Harbour; Right 2 pix - Paul at Mic; Me at Mic

Jack and Dan were both within 6m above sealevel, my location a little higher at ~ 10 metres. Due to the cliffs Paul and I weren't gonna get any lower !!. In fact the rock ledge below us slowly became awash with the incoming tide as time went bye. We started out by calling northwards to Dan, when Jack popped up on the 2m liasion freq saying "I can hear you!" WOW the dish was facing away from him. We didn't hear anything from Dan at that stage so we swung the dish around 180deg and had an excellent QSO with Jack. We then stood by as Dan and Jack attempted a QSO, they succeeded tho very marginal. Shortly after that we listened again and finally heard the CW beacon from Dan. It was wildly fluctuating both in signal strength and in frequency. Initially blaming the freq shifting on LO instability. Later realising that all our LO's are pretty stable and would not account for the rapid changes observed. Mulling over this with Jack we thought maybe it was doppler shifting caused by reflectings of the waves and swells. Whatever the cause it was a new and interesting observation.

Left pix - Dan (Blue Cap) @ Anna Bay; Middle pix - View south to Jack; Right pix - View north to Dan

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Dave, VK2TDN

Sat, 16 Jan., 2010
Summer FD (VHF-UHF Contest) Outting
I attacked this fieldday with a much greater determination than in previous years. In fact it was the first time that I had submitted a log and to my suprise I managed 10th place in the 8hr, single op catagory. My chosen location was Sugarloaf Rdg., Horsley Park area, Western Sydney. I was active on 2m, 70cm, 23cm and 3cm. Worked a number of 23cm stations. The numbers on this band have been growing well over the last 2 years. I worked the 2 stations that were on 3cm in the Sydney area, Jack VK2TRF and Justin, VK2CU. Justin had Dan VK2GG's 10GHz gear on loan. And of course I worked good numbers on 2m and 70cm.

The pic shows the 10GHz dish beaming towards Top Ryde to Jack's location

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Dave, VK2TDN

Sat, 20 March, 2010
John Moyle FD Outting
Although I initially planned to take part in today's JMFD contest, it didn't happen. Jack, Dan and I instead spent the time trying out gear and mutual communications between the 3 chosen sites. This outing was primarily a prelude to the Winter FD in mid June. Jack initially went to Heathcote in the SE corner of Sydney. Dan went to Mobbs Lookout in Carlingford, and I went to a spot in the Blue Mtns between Faulconbridge and Linden. We tested out, 23cm FM between Dan and myself, good signals. 13cm ATV between Jack and Dan and Jack and myself. 6cm between Jack and Dan was an easy 2 way path. Jack's signal to me, once lined up, was a solid P4 to occassional P5. For 3cm we didn't even use SSB as signals on FM were full scale and easily heard. Whilst there, I tried out one of the recently acquired 400mW amplifier off eBay it works well. Rob, VK2GOM, joined me at my location and had his first QSO's on 1296 MHz and 10GHz. It definately got him more enthused about the iminent arrival of his 10GHz xverter from Khune. It was a good day but a very hot one with a bit of sunburn occurring. Michael, VK2FMJC, also called in for a while.

Left 2 x pix - Rob, VK2GOM on 10GHz; Michael and Rob - 5.7GHz ATV; Right 2 pix - Dan - 10GHz; Dan - 5.7GHz ATV

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Dave, VK2TDN

Tues, 6 Apr., 2010
Rob, VK2GOM's new 10GHz system, Another new station on the band
Rob, having finished the construction of his Khune 10GHz kit, in record time, came over to my home today and we did a tune up. All went well and it put out a healthy 200mW on 10.368GHz. Dave, VK2CQ, joined us later in the afternoon, in time for a first on-air test across the length of my section. All went well other than some intermittant antenna relay switching probs. Rob sorted these out over the next few days.

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Dave, VK2TDN

Mon, 26 Apr., 2010
An outting to check out sites and gear
Today had a 3 fold purpose, 1) .. to give Rob, VK2GOM's new 10GHz system a decent workout. 2) .. for me to check out my planned new location at Wentworth Falls in the Blue Mtns. and 3) .. for Jack, VK2TRF to try out his newly acquired Slotted waveguide omni for 10GHz. We didn't bother with any other bands, this was purely a 10GHz outting :). Dave, VK2CQ joined me at my location. It was an interesting adventure getting my car to the site, as the gravel road (Read as Track) hadn't been graded for who knows how long. The first 100-200 metres was dreadful, deeply scoured out by rain runoff. The depth of the "ravines" could have hidden my Toyota Echo, hahaha.
Jack came over to Top Ryde, where he could beam west to both Rob and I. Rob went to to Sugarloaf Rdg in the outskirts of western Sydney. The afternoon was a great success, Jack's slotted WG worked a treat. It means that for his rover entry in the June winter FD, he won't have to point a dish, just fire up the slotted WG with his beacon and the rest us can align on him. Jack found that with Rob pointing at me, he could still hear Rob easily by reflections and the 3 of us could converse without realigning our antennae.
There was 67km between Jack and I, 45km between Rob and I and finally 23km between Rob and Jack. All paths LOS. Here's something I haven't added before, pathplots. Jack, Dan and I use a program called ukWTools, it uses space shuttle radar elevation data. We dont use it for absolute data info, rather it gives us a very good idea of if there is a LOS path between two points. This indicates the sort of path losses we might expect between 2 points of interest.

Pix from Rob's location, centre pic shows the dish pointing to Jack at Top Ryde

Pix from my location, zoomed and normal view to Sydney; Dave, VK2CQ by dish; me by dish
The view out across the Sydney Basin is awesome, am looking forward to making this a regular microwave site

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Dave, VK2TDN

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Page created 08 July 2008
Page updated 28 Apr 2010
Dave, VK2TDN