Thursday, 25 May 2017

First Outing on 24GHz!

Mike G0MJW has kindly lent me his spare 24GHz (1.2cm) system to test. I've been wanting to find out about the propagation and experiment on the millimetre or EHF (Extremely High Frequency) bands for awhile. I'm super interested in seeing how this part of the radio spectrum performs compared to 10GHz (3cm).

Mike's kit is a Nortel ODU modified from 23GHz which provides a complete "24GHz in a box". An internal relay requires positive volts up the the coax to switch to TX, and the unit requires 1W at 432MHz to generate 0.25W at 24,048MHz. The FT790R Mk1 is an ideal driver radio for this unit. The Nortel power supply requirements are between -36V and -48V, so a DC/DC Converter was used powered from a separate 12V leisure battery source.

On Sunday it was the first UKuG 24GHz/47GHz/76GHz Cumulative and I was eager to see if it all worked! Mike had warned me that the unit had been stored for the past 10 years and there was a frequency offset of +/- 150kc.  So my plan was to test the RX first and then try and find someone local to boldly attempt a QSO with.  Like all of my Microwave endeavours I was prepared for complete failure and hardship.  That way anything positive is a pleasant surprise!

I need to spend some time working out how to fix the unit to a mast.  But for now a small white plastic patio table was utilised to provide a flat surface on top of my surveyors tripod. This seemed to provide a useful workable solution!

First stop was Knowl Hill IO91OQ about a 10 minute drive from my home QTH. I decided to visit a site north of the A4 which is higher than an alternative site just to the south.  The location is accessed from a footpath and presents a SE to S facing hill. I quickly set-up in a field of sheep. The first objective was to try and find the Reigate beacon GB3SEE (62km to the SE) to test the RX and to find the frequency offset. The transverter RX seemed to be working as there was a healthy increase in noise, and on TX a reassuring clunk of the relay! However, after significant sweeping of the band up and down, and pointing the dish to where the beacon should have exactly been on a direct path, nothing was received? This was disappointing but you have to be thick skinned for all this microwave lark, see my other blog posts about 10GHz!  Whilst onsite Mike G6TRM/P in JO01QD (162km to the SE) near Dover phoned me. We tried to complete a QSO over what would have been a very marginal heavily obstructed path,  but nothing was heard.  We are yet to make the path go on 10GHz, so 24GHz was somewhat optimistic!  However, its always worth a try.

24GHz from Knowl Hill, looking SE

The 2M Microwave talkback frequency 144.175MHz was busy with chatter. With just the FT-817ND and a 2m/70cm Whip antenna Keith GW3TKH/P on Blorenge (IO81LS) and Roger G8CUB/P with NeilG4LDR/P on Hackpen (IO91CL) were all loud. Martyn G3ZME/P on Brown Clee (IO82QL) was also heard looking for QSO's. So I decided to drive the 35 minutes to Christmas Common (IO91MP) about 850ft ASL on the Chiltern Ridge. After a quick "CQ Microwave Contest" on 2M I found Neil G4LDR/P who was still on Hackpen (60km to the W). We tried a couple of times on 24GHz but with no success. The Wx was hot and sunny (with no obvious humidity problems) and the views at both locations were amazing, which made up for the lack of QSO's!

24GHz from Christmas Common, looking NW

It was great to get back out again /P. I plan to drive down to Reigate and park up next to the GB3SEE 24,048.9600MHz beacon to work out the exact frequency offset of the Nortel unit - before the next EHF UKuG Cumulatives in June, September and October.

Wednesday, 29 March 2017

First 3cm QSO in 2017

It was a clear dry evening last night at 8.30pm in the March SHF UKAC and I set-up both 13cm and 3cm dishes on the tripod at Remenham Hill, my normal /P perch in IO91NM. This is a roadside layby just north of Wargrave, with clear views of the horizon in all directions.  Quickly I worked G4BRK and G4LDR on 13cm SSB.  But 3cm remained very quiet.

For the first time from this QTH I managed to find the GB3SEE Reigate Beacon on 10368.850MHz. It was weaker in strength than from some of the other sites I use nearby, Remenham Hill must be obstructed to the SE.  It was good news finding the beacon, it meant that I could work out the approximate offset of my transverter, which was calculated to be about 22.3KHz high of the dial frequency on the FT-290R.

With my frequency better defined, I tried again on ON4KST with Neil G4LDR in Salisbury and we managed to work each other on 3cm. Neil's signal was very distorted by rain scatter from a set of rain clouds that were between us, moving my way from the SW and W!  Rain scatter produces a profound doppler shift with signals moving up and down in frequency and on SSB this sounds almost auroral. The rain clouds last night were moving quickly towards me and the scattering effect meant that it was difficult to resolve Neil's signal, but we managed to complete a 3cm QSO with RS helping. My first 3cm QSO in 2017.

At about 10pm the rain arrived overhead and I got absolutely soaked!  I did manage to hear M0GHZ and G4BAO on 3cm before packing away, but my 150mW was too QRP for them to hear me. Fortunately no water got into the transverter boxes and everything is back in the shack drying out, ready for another outing in next months event!

Wednesday, 1 March 2017

Half a QSO on 3cm, and not many more on 13cm!

It was a very windy, cold and miserable evening for the February SHF UKAC, and my first /P outing in 2017. I decided to venture out to what is becoming my go-to 23cm /P site at Remenham Hill IO91NM (51.537096, -0.854341), just one small QRA square north of my home QTH in Wargrave IO91NL.

The advantage of this site is that its extremely easy to get, it’s just 10 minutes drive from my house with good access, roadside parking and level ground.  The downsides are that its a very noisy site with lots of cars whistling by at speed, and very open to the public.  A couple of times I’ve had cars park up alongside me, and some strange curious visitors wander about which is not ideal!  Its on top of a small hill about 99m ASL (nearly twice the height of my home QTH which is just 57m) with clear views on the horizon in all directions. The lay-is beside the busy A4130 between Henley-on-Thames and Maidenhead.

Set-up was quick, despite a strong gusting wind and the tripod was guyed with the 1m grid dish for 13cm mounted at about 2m off the grass verge. On 13cm (2320MHz) I use a DB6NT G2 Transverter which produces about 0.8W into a TP-Link 1M grid dish TL-ANT2424B Wi-Fi aerial. This works amazingly well its a 1:1 VSWR match and provides 24dBi gain, so about 200W ERP.  First in the log was Neil G4BRK in Garford near Abingdon IO91HP at an easy 38km distant. Soon after I worked Neil G4LDR IO91EC near Salisbury at 70km for my only other QSO and ODX. I heard M0GHZ (IO81) and G8OHM (IO92) on 13cm, but they could not hear my QRP, I need more power at the masthead.

The 3cm dish was proving to be difficult to mount on the tripod and I had a problem with the fixing. Unusually I could not find the GB3SEE beacon in Reigate on 3cm which is always worrying as it means I don't then have a reference for the frequency offset which is usually about 19KHz high.  It was now getting very windy and at this point I decided it was safer to be holding the dish by hand than have it fly off the tripod! I tried with G4LDR on 10GHz it was super difficult to keep a steady beam heading, but he was much stronger on 3cm than on 13cm. Neil could detect me but could not read my signal.  There was distortion due to the bad weather conditions and no doubt signal scattering as the path is highly obstructed.  My random dish alignment probably didn't help!  I was using the FT-290R, barefoot DB6NT G2 transverter with 0.15W output into a 60cm offset dish, so about 150W ERP. At least this site holds useful potential for other SHF UKAC outings and future QSO attempts.

If the Wx is better and I can make some station improvements on 13cm and 3cm (re-boxing both transverter systems to add various sequenced RF amplifiers and LNA's) I hope to return to this location again in a months time for the March SHF UKAC with more power and a better chance of success.

Sunday, 28 August 2016

A Happy Hour at Lacey Green!

Today I spent a happy hour at the roadside lay-by at Lacey Green, IO91OQ for the penultimate UkuG 10GHz contest. Lacey Green is a high spot on the Chiltern Ridge (774ft, 235m ASL) with fantastic views to the West and North.  The Wx had not been great with lots of rain earlier in the day, but I managed to dodge the precipitation by venturing out late in the afternoon. 

Conditions seemed to be average with no rain scatter enhancement.  With just the DB6NT G2's circa 150-200mW and the 60cm offset dish, I completed 4 QSO’s which is a record number for me - usually its just 1 or 2!  Today proved to be my busiest 10GHz session so far in the the SHF UKAC’s and UKuG contests, a really pleasing result. 

On arrival after a quick CQ on the Microwave Talkback frequency of 144.175MHz, using just the FT-290R Mk1 with 2.5W and its telescopic whip, the first in the log on 3cm was G3ZME/P. Martyn was operating with the Telford Group up on Brown Clee in Shropshire IO82QL (1,770ft, 440m ASL) at a distance of 154km.  This QSO beat my previous ODX of 147km (when I last worked Martyn from IO91MP Christmas Common) and means I’ve finally worked beyond the magic 150km wall!

After another CQ on 2m and a bit of meeping on ON4KST chat, the next 2 QSO’s were quickly arranged with the father and son team of Stewart G0LGS/P and Matt 2E0MDJ/P who were on Cleeve Hill in Gloucestershire IO81XW, the highest point of the Cotswolds (1,083ft, 330m ASL) at a distance of 91km.  Both were amazingly strong signals on 144MHz and 10368MHz.

I then tried several times with M0HNA/P the Combe Gibberlets team (Brian G4SJH and David G1EHF) on Walbury Hill near Hungerford (974ft, 297m).  We worked each other fine on 2m SSB at 60km, and although I could detect a very weak signal on 3cm we were unable to complete a QSO.  The SW is not a great direction from the Lacey Green site and the path to IO91GI is very obstructed with several other hills in the way. We have tried lots of times in UKuG contests from various locations and I’m sure we will make a QSO one day soon.  For sure it will not be for want of trying!

Last in the log was Noel G8GTZ/P located just south of the M3 at Basingstoke which was arranged by mobile phone.  Noel was at the same location I tried in IO91KF when I worked him at Hannington in the May SHF UKAC contest.  It was a very pleasant surprise to work Noel at 56km, as it involved pointing the dish just West of South - again not a great take-off direction from Lacey Green.  For this outing I had the SoundLab 4m Gear4Music tripod which I use in the UKAC's with me.  I managed to elevate the dish so that it was about 2m above the ground clearing a nearby hedge, which seemed to do the trick!  

Before packing up I contacted Gordon G3WJG in Chorleywood to see if he could hear my 3cm NBFM signal. After pointing the dish across the road and just South of East, we tried several times but without luck.  Gordon could not find my signal due to a number or variables, including frequency.  We will try again another time.

Overall this was a very enjoyable UKuG contest and I plan to revisit Lacey Green again for either the October or November SHF UKAC’s with 3cm and also 13cm kit.

A record 4 QSO's in 1 hour on 10GHz. Busy!

Monday, 27 June 2016

Sunday Afternoon on Streatley Hill

For the 2nd 10GHz UKuG Cumulative contest on Sunday 26th June, I decided to try a new site at Streatley Hill.  This location is called Lough Down accessed via the Lardon Chase car park.  NT-owned, this hill is just to the west of the 'Goring Gap', where the River Thames cuts through the Chiltern Ridge.

Looking at the HeyWhatsThat path profiler, on paper it looked like a good spot to try and reach Noel G8GTZ/P at Hannigton (IO91JH) and maybe the Combe Gibberlets group M0HNA/P on Walbury Hill (IO91GI).

The challenge with finding a decent spot on the Chiltern Ridge is that wherever you go there are nearly always lots of trees and hedges obstructing views.  Unfortunately this was the case at this site.  The takeoff was great S to SE and the GB3SEE beacon (IO91VG) in Reigate was soon found at good strength on 10368.850MHz at 70km, but SW and W were blocked.

After a quick 'CQ Microwave Contest' call on the 2M talk-back frequency of 144.175MHz, Noel was easily worked on 3cm at 24km.  I find 2M talk-back to be absolutely essential on 3cm /P, and I could hear Noel chatting to M0HNA/P and also trying to work Brian G4NNS in Andover.  I tried with M0HNA/P on 3cm and I could just hear their dots, but they could not hear me.

The mobile data signal was unusually good, and I logged into ON4KST chat and tried to work Stewart G0LGS/P on Brown Clee, but the path W was also blocked.

I had more problems with the pan tilt head on the tripod (a more robust mechanical solution is needed), the 2M amplifier did not seem to be working that well (despite testing prior to going out) and I need to make a small repair to my 2M HB9CV.

After about an hour or so onsite it started to rain so I packed-up! This site had a long walk in and out, and with lots of heavy kit that wasn't great.  Being a NT site there were tonnes of Muggles inquiring about what I was doing - which I don't mind explaining - but typically folks were walking by asking questions just as a QSO was trying to be completed!

Pleased to get another 3cm QSO, but I wont be going back to Streatley Hill.  I will continue my hunt for useful microwave sites in IO91, but there does not seem to be that many really useful ones within a one hour drive of my home QTH in Wargrave!

Monday, 30 May 2016

Two trips out in under a week!

Its been a busy start to the 2016 3cm /P season, with 2 trips out in under a week!   

Last Tuesday May 24th was the May SHF UKAC - and my first chance to get out /P on 3cm. On hearing that Noel G8GTZ was going out to Hannington, I decided to head South to Basingstoke to see if I could work him.  We tried last year but didn't make it from Knowl Hill.  It was a lovely sunny evening and dry for a change, perfect for taking the gear out on the hills.  Basingstoke is about a 45 minute drive and I set-up at 9pm local on a roadside verge just south of the M3.  This was a new location for me in IO91KF, that is on the Farleigh Wallop road just as it goes over the motorway.  At 9.07pm I had my first QSO on 3cm SSB with Noel G8GTZ/P at 11km to Hannington, which is due north and LOS.  Noel was very loud and a super easy QSO.  It was great to finally make contact and also to score some much needed 3cm points for the Drowned Rats Radio Group, our first on the band in 2016!  This location is good for N, and NE but not great in other directions due to the density of trees nearby.  I tried and failed with G4BAO (JO02), M0GHZ (IO81), G4LDR, G7JTT/P and G4RGK (IO91).  I did hear CW from Dave G4RGK at 78km in Marlow but he could not hear me.  I also took the new 6cm WBFM kit, but no one was QRV that was local enough to try it out.

The first UKuG 5GHZ and 10GHZ Cumulative took place on Sunday May 29th - another chance to get operational.  I set-up from home first in the back garden at IO91NL but it was a waste of time, what with all the trees and high hedges around.  So I went up to Knowl Hill IO91OM which is my local /P site about 15 minutes drive.  I parked off a small road on the north side of the A4 and walked up a footpath into a field of Buttercups.  This excellent little site is a small E-W ridge that has a useful take-off to the South.  The GB3SEE beacon in Reigate IO91VG at 49Km was a solid 59 copy as usual with my 60cm Offset Dish.  To start with I tried to work Mike G6TRM/P who was out portable in JO01LD near Ashford, Kent but we could not make the 128km path go, the second time we have tried.  I still need to upgrade my system by adding the DB6NT LNA and the 1W Amp.  Next via KST I tried with Rob G0PEB/P on the IOW (IO90) and then I swung round to Martyn G3ZME/P (G3UKV) who was out with the Telford uW Group on Brown Clee (IO82) but that path failed also.  I did hear and work G3ZME/P on the 144.175MHz talk-back frequency but the Knowl Hill site is obstructed to the NW, and a 3cm QSO was not possible.  Taking 2M (so using the same FT290R Mk1, and 2.5W into an HB9CV) proved valuable, as a CQ to the South produced Colin G4EML/P who was 73km away at Storrington on the South Downs, IO90SV near Worthing.  We switched to 3cm and his signal was so much stronger, peaking 59.  It was great to get a 10Ghz QSO in the log, and also to work a new locator square on that band.  I had a few problems with the new dish mount as the pan/tilt head had wiggled loose, - I will have to fix that before the next outing.  All part of the fun!

Upgraded Tripod Mount with 60cm Offset Dish
G1DFL/P at Knowl Hill, IO91OM Looking South

Sunday, 24 January 2016

2016 - More to learn, more to improve, more to achieve!

With the experience I gained on 10GHz last year, I’m super excited about what’s possible in 2016. I learned a lot, I have a lot of system improvements to make, and there’s a lot for me to still achieve, for sure!   

Here’s a few things I have on my “winter to-do” list:
  • Complete my tripod dish mount system - This will enable me to have a have a robust and stable platform for my dish plus a 2M talkback beam. Involves interfacing a 2” vertical pole with my camera pan/tilt head, attached to my Leica Surveyors tripod.
  • Create a separate 2M SSB/FM talkback system – Many remote hilltop sites have surprisingly poor mobile voice/data coverage.  In the UkuG contests, as well widespread ON4KST use, I found that 144.175MHz SSB remains widely used to attract new contacts.  Also talkback is really useful for helping with dish pointing.  Last year I was having to disconnect the FT-290R Mk1, and then use its telescopic whip to go back to 2M.  This year I will bring my TR-9000 with a small beam.
  • Re-house my transverter – /P systems get bashed a bit and everything needs to be reliable especially all power and RF connections.  A great way of coping with malfunctions is to have a “first aid” box of spares etc.  Also everything inside the transverter box is valuable and needs to be protected from rain and mud ingress.  
  • Improve my 3cm RX and TX – I have a DB6NT HEMT MKU LNA 102 A to add into the system, as well as a 5W SSPA.  This will enable me to hear better and be heard by more stations.  Last year my ODX was 147Km and I want to better that to be 250km+.  This will involve a more complex system with the LNA and SSPA correctly sequenced using an SEQ-2. 
  • Build a WBFM system – I’d love to help some other folks get on 3cm in a quick and easy way.  So I plan to build a second 3cm capability.  This will be simple and cheap and involve separate WBFM TX and RX systems.  Specifically I’m keen to help some new stations experiment, learn and have fun on 10GHz using bits and bobs that collectively cost “under £50”.  For RX this will be a simple 45cm Sky Minidish->PLL LNB->BiasT->RTL Dongle->SDRTouch->Android Tablet system.  For TX I am thinking a Solfan/C&K Gun Diode->Horn with a Modulator/PSU circuit.  I’m especially keen to get some of my colleagues in the Drowned Rats Radio Group (DRRG) M0HRF up and running on 10GHz, so as a team we can win more points in the SHF UKAC!!
Reflecting on last year, one of my highlights was discovering how super helpful and encouraging GHz folks were towards me getting my station back together and operational again on 3cm.  Shout-outs due to Neil G4LDR, Brian G4NNS, David M0GHZ, Andy G6TRM and Noel G8GTZ in particular, have been very supportive.

At the end of last year Noel G8GTZ kindly invited me to his QTH in Basingstoke to give my system an “MOT”.  This was a really insightful and helpful exercise.  In the December SHF UKAC I had problems on Coombe Hill with overdrive issues between my FT-290R Mk1 and the DB6NT Mk2.  So that was the first challenge to fix.

Noel is a well known Microwave/ATV guru and a really knowledgeable radio experimenter, with an impressive array of test equipment.  This meant that he was able to help tune and set-up my system correctly.  He measured about 150mW out which is not that far off the 200-250mW rated spec from the DB6NT.  There’s some more tuning that can be done for sure as we didn’t adjust the FT-290R drive, he just backed off the settings that were probably causing the overdrive problem inside the transverter.

It was also a chance to test some new additions I’ll be bolting to my system for 2016.  Last year I acquired a 700mW in 5W out SSPA and with 150mW this gives a very useful 1.5W out, so 10x my current output, which will definitely help me to be heard!  Ultimately I’d like to build a driver amp for this to feed 1W in to get the full 5W out, but that can wait.  The 1.5W will make a massive difference, with a 30dB offset dish that’s over a KW ERP!

Noel also hooked up my newly acquired DB6NT LNA onto to his test gear.  I was really impressed by the difference a high quality pre-amp made, improving the system gain from 18dB to 42dB and reducing the system noise figure from 2.69dB to 1.99dB NF, see attached photos.  ...When /P in the field I’m expecting this to make a significant difference to what I can hear!

A big thank you to Noel for the “MOT”.  When I’ve re-housed my transverter to form my “2016 system” (with the 1.5W SSPA, LNA and SEQ-2 all wired-up), I hope to pop-back down to Noel’s QTH for a re-test, before I next venture out.

I’m really looking forward to lots more QSO’s in 2016, and - weather/family/job permitting - I plan to be active in the following contests:

  • SHF UKAC series (4th Tuesdays, aiming for May, June, July, Aug, Sept & Oct)
  • UKuG 10Ghz Cumulatives (29 May, 26 June, 31 July, 28 Aug & 25 Sept)
  • Region 1 UHF-SHF Weekend Contests (7-8 May & 1-2 Oct)

Here are my 2016 top 5 objectives:
  1. Build a WBFM system and help to get some DRRG folks on 3cm
  2. Improve my station, work more people, and increase my ODX to 250Km+ 
  3. Work a new country (GW easiest from IO91, but PA or F would be fab!)
  4. Experiment more with scatter modes including RS and AS 
  5. Try some new paths, from some different sites in IO91
So lots more to learn, a lot more work to do to improve my system, and lots more to achieve on 3cm in 2016.  I hope to work you!

G1DFL 10GHz System without LNA (18dB Gain, 2.69dB NF)
G1DFL 10GHz System with LNA (42dB Gain, 1.99dB NF) - a big difference!