Thursday, 31 December 2015

Lunch in Cambridge

Excellent New Year's eve lunch with some of the Cambridge hams at Horningsea today.
Lots of talk about EME and testing systems. This was quite relevant as I have been playing with MAP65 over the last few days. I want to be able to monitor the 40-50kHz of 23cm where the JT65C activity is located.


MAP65 on 2m EME

My previous attempts at getting MAP65 to work have been unsuccessful. Recently I became aware that it was possible to use the SDR-IQ on the IF output of the K3 with SDR-Radio as the interface to MAP65. My attempts to get it to work were getting nowhere until I spoke to G4IDR.  Dave talked me through setting it up. I had not spotted a small icon on the SDR-Radio screen. Once pointed out it was possible to start MAP65 and send data packets to it.

Tuning the K3 to the 144MHz beacon band it spotted and listed GB3VHF. Clicking on the display trace of GB3VHF produced a decode of the beacon.

After this I reconnected the 9 element yagi and masthead preamp and left the yagi pointed towards were the moon would rise in a few hours. 

15 minutes after moonrise I came back to see a whole load of stations listed, including RRs and 73.
Several of the stations were obviously direct terrestrial signals from the nearer continent, but at least three were by moon reflection from their DT timing on the decoded display. All in all I was pleased with this result and I'm now looking forward to connecting to my 23cm Eme system and looking at how many signals I can decode on that band/mode.


Monday, 21 December 2015

Some low noise tests

Merry Christmas,
I had intended to work on my EME dish today. However, the weather has been very wet and windy since mid morning. Consequently I decided to do some measurements on the LNA with a view to reducing my EME system noise temperature on 23cm.

After (re)reading a number of interesting articles on noise figure reduction by SM5BSZ and RW3BP I thought that I would measure the insertion loss of my LNA protection relays. These are SMA types by one of a number of manufacturers and all are surplus ( second user) SMA types with 3  in-line SMA female connectors. All are12V working.

After carefully calibrating my HP8753C network analyser ( warmed up for several hours) i found that the best I could do was 0.071dB insrtion loss from a Totsoel with 0.1dB from a Teledyne CCR 33S80
I must stress these are used relays. I have to use what I have!

The net result of using the Totsoel relay with an SMA90 bend to the feed and SMA male back to back adapter between the relay and VLNA is 0.38dB as a noise figure.
This is quite good but I believe I can improve on it using some of the techniques describd by RW3BP.
The back to back adapter can either be eliminated completely or replaced with a modified version using a piece of UT141. The probe to relay connection can be made in one piece to eliminate yet another SMA connector.
Now to try a few of thse ideas.

Sam


Saturday, 14 November 2015

Kangaroo Island

  
Back from Tasmania for a few days and went to Kangaroo Island. The island is 20km off Cape Jervis, south of Adelaide.
Two nights in Kingscote allowed us to visit Flinders Chase Wilderness area at the western end of the island and an hour or so from Kingscote.

Admirals arch and the New Zealand fur seals were first.

 Followed by the remarkable rocks


 
The heritage walk behind the Visitor centre provided both koalas and kangaroos





Sam










Saturday, 7 November 2015

And on to Burnie

We hadn't planned to visit Burnie, but as it turned out, we have!
After crossing more mountainous terrain we found ourselves near Devonport. From there we just sort of wandered along the northern coast as far as Boat Harbour Beach. Beautiful white sands.
As we had already booked into a hotel in Burnie, we wondered back here. At dusk we are going to wander over to the Glade and see if there are any platypus around this evening.

Wallabies and wombats



More anon

Sam
Here at Cradle Mountain, Tasmania, we are surrounded by wildlife. Wallabies abound (pardon the pun) around our cabin at the Lodge, and wombats roam freely.

Wallaby outside the cabin


As was this guy!

We visited the nearby Devil's Cradle to see the Tasmanian devils and quolls


And no view would be complete without this fellow wondering along the roadside





Tuesday, 3 November 2015

Visiting VK7

We have been in VK for several days and are currently in Hobart. VK7MO kindly agreed we could stay at his QTH for a couple of nights and Rex has shown us around his fine city including a trip uo to the very top of Mount Wellington. Although it is now Spring down here it rained heavily yesterday, up on Mount Wellington it had fallen as snow. In consequence  it was extra cold at 1270m!

Yes, that is Hobart down below.........

L
Rex and I have had long talks about 10 and 24GHz EME and the benefits of portable EME operation at these frequencies.




Tomorrow we will set off for Queenstown and Strachan. The weather promises to be better later this week.



This is one view from Rex' QTH, towards the east and out towards the Tasman peninsula and Port Arthur.

Sam






Friday, 23 October 2015

Playing remote

Since upgrading to Win10Pro I was made aware that I could operate two such equipped PCs in remote mode without subscribing to Logmein. I hade never found LMI to be all that easy to use, even after playing with a number of the settings. Screen rendition on my rotator screen was awful. I have cancelld my automatic LMI renewal due shortly.

With W10Pro remote desktop the screen quality is excellent and I can see the individual rotator markings much clearer than before.
All remote functions are working well except the MS HD3000 USB camera. This is an excellent camera, but it won't work over the RD connection. This might be due to the driver from MS not having been upgraded yet or it might be something else I haven't identified! The are known problems with HD3000 on W10

At the moment I am running my SpidRas dish controller over the remote system and monitoring sun noise on my indoor shack TS2000X. 

*****Update*****

This evening the St Martin EME expedition TO2EME was consistently in the -23dB range on 23cm. Some of the bigger stations were unbelievably strong on the JT screen! G3LQR was a good (EME) 569


Sam


Wednesday, 14 October 2015

VHF DX

Following on from G4SWX's talk on VHF dx over 3000km I was interested to hear from WA1ZMS about the possible, recent, reception of his high power 144.285.5MHz transAtlantic beacon, located in Virginia, by a VHF op in Brazil. Assuming it is genuine and I've heard the phone app recording, but am not 100% convinced, it represents a truly remarkable distance for 144MHz and is certainly well in excess of the 3000km mentioned in John's talk. Even more remarkable is that the path is about 85 degres off the Great Circle!

If genuine then the reception of the ZMS/B beacon by PU2XIZ, and passed on by PY2DS on the phone, PY2DS feels he heard the CW and there is a very valid chance it's a true copy. 
It was possibly tropo enhanced TEP and that is being investigated using modern analysis software.
Part of the beacon sequence is clear on the recording, but not all of it.

I am sure we will hear more about this remarkble claim in due course. AO7 (I think) showed that long distances  were possible on 144MHz but not much has been reported in recent years.

Whilst I feel there are still some questions about the authenticity of this report, if proved true then it should be possible to work some truly long distances on VHF by carefully observing Hepburn and the F5LEN propagation web pages and acting on those that seem to offer good possibilities.

Sam


Thursday, 8 October 2015

RSGB Convention

I've spent much of this week getting kits ready to take to the RSGB Convention this weekend. I will only be there on the Saturday this year due to other commitments.
My thanks to G7OCD for producing more assembled Anglian 144MHz transverter boards in time for me to kit them ready for the weekend.
I've also kitted up 8W 144MHz PA short kits, DG8 144MHz masthead preamp short kits and a number of PGA144 low noise preamp kits.
There is no trade facility at the Convention, but if you want my of these kits you can find me either on the UKuG stand or in the VHF lecture stream in the afternoon, especially GM3SEK's talk. The other VHF talks are also very worthwhile attending as is the Microwave beginners talk by Simon. I saw his talk slides at last night's Pye and Pint CambHams get together in Barton.

Sam


Wednesday, 30 September 2015

23cm EME revisited

After the best part of three years QRT on 23cm EME I thought that with the dish relocated to a more favourable position in the garden and yet another dead wych elm tree removed ( Ivy is still a good 'noise generator!)fom the garden boundary, i would have a listen during the September 2015 ARRL all mode EME contest.
In total, over the two days and also Monday evening, I decoded or heard ( on CW or SSB) more than 20 different stations, with the best being JA6AHB. Signal levels ranged from -5dBJT down to around -22dBJT.
I looked carefully for VK5FA who was running just 40W but even though I knew he was there when working other Europeans,  I could not get a JT65C decode from him. Maybe next time. Andy is located in Adelaide and as I am going there next month I thought it might be nice to work him or at least give him a signal report.
Today I started to terminate my 14m length of LDF5-50 transmit cable. The cable runs from the shack to the dish so that the amplifier can stay in the warm, dry, shack, as previously. Although the cable loss should be 0.8dB at 23cm, the measured loss on my network analyser stubbornly refused to go below 1.3dB. I suspect the extra loss is from the old connectors I am using. With 200W in the shack this means I will just about achieve 100W at the feedpoint wih the additional loss of the short patch lead around the rotator. That is a smaller transmit signal than I used to achieve with the dish closer to the shack using around 8m of 5-50.
If I am going to take this seriously I will have to think about moving the amplifier closer to the dish. Maybe even run 300W in the old Storno case as I had previously planned to do.
The VLNA preamp performance is quite adequate and gives a sun to cold sky ratio closer to what I would expect than I saw previously.

Sunday, 20 September 2015

Crawley Microwave Round Table

I went to the Crawley MRT today. I had missed the last few years because of other commitments.
It was a good as ever. Although one of the smaller events in the UK amateur calendar, it is both very friendly ( as I used to say in my RadCom column) and an opportunity to see some of the other microwave enthusiasts I don't see for months on end.

I especially enjoyed Roger, G8CUB's talk on 24GHz as I had just managed to relieve Simon, G3LQR, of his portable 24GHz transverter. This hadn't been used for many years and was just what I wanted to allow me to align the portable dishes for the higher bands. My own efforts at a portable 24GHz transverter, using Thales and Elcom modules had proved less than ideal and had been cannibalised for parts for my new 24GHz masthead home station transverter. 

I'll have more to say about 24GHz home station operation in a later blog.

In the meantime the portable system will be used with one of several dishes for path alignment when setting up higher bands.

Simon also kindly allowed me to talk away his old 47GHz transverter. This needs a bit of work to make it more user friendly, but it will prove to be the basis of a very effective portable 47GHz system. It is many years since I held the 48GHz UK distance record in conjunction with G4KNZ ( 39.8km!). My old NEC-based transverter is no more........

The longer term plan is to make a 134GHz transverter. I have a suitable Elcom synthesiser and Roger, G8CUB, is reprogramming it for me to produce the two (switchable) 11GHz LO drive frequencies required. I have a (suitable?) 34GHz tripler and the DB6NT 140GHz PCB. Roger has ageed to bond/solder the diode onto the board for me.
With 24GHz and 47GHz portable to help align dishes, the 134GHz may allow me to make my first steps onto this primary amateur band.

Sam


Thursday, 17 September 2015

Anglian transverters

I have started to take delivery of another batch of assembled Anglian 144MHz transverter boards. The first of these have already been dispatched to their new owners. I have a number ready to go out and another panel or two arriving later this week. Details on www.g4ddk.com

New deliveries of component reels have been arriving steadily for the last few weeks. I'm now looking forward to getting back to doing some actual radio operating!
Sam

Thursday, 27 August 2015

Clearing the bench

I have decided it is time to clear the workbench. I am down through the first (top) layer and starting to find the interesting stuff like coax adapters, tools and missing components.
I have decided that it is time to change the 15 year old + anti-static matting and the heat proof matting used when seam soldering PCBs into tinplate boxes. It's looking like a run to Rapid Electronics tomorrow.... First I have to reach that layer, though!

I'm hoping a clean bench will provide the encouragement I need to get on and complete some of the current ( stalled) projects.

What prompted this?
Acquiring more parts yesterday when the local computer shop announced it was closing this week and a number of PC processor heatsinks and cooling fans were made available for a small donation to the local sea rescue service. Also the imminent arrival of more amplifier PCBs and reels of components.
I also need the room to finish off the new 24GHz transverter.

Time to go and start digging, sweeping, examining, storing and throwing out, again.
Bye.




Sunday, 9 August 2015

More 9cm EME

Having built a new VLNA9 to replace the faulty one I was trying to use I started to get sensible results using my 2.3m dish on 3400MHz EME.
Sun noise was 12dB above cold sky and moon noise 0.35B above cold sky. These numbers are averaged from a large number of readings using continuum mode in Spectravue running on my SDR-IQ.

Having found the moon I was pleased to see a digital signal from OK1KIR. It took me a while to realise it was JT4F and not JT65C. By the time I had switched modes they had gone......I only know it was them from their posting on the HB9Q logger. There is little doubt about who it was as activity at time was low.

A little later Peter, G3LTF, offered to transmit for me. At this point I realised that the transverter LO had drifted when I couldn't see Peter's CW and knew I should. I checked the beacon at Martlesham and found it was about 13kHz low of where I expected it to be. It was pretty warm in the rack by this time. With this corrected I was able to see and copy Peter's CW. Peter then switched to SSB and with a little tweaking of moon beam heading I was able to copy his SSB at up to 52. In terrestrial that would probably equate to 41, but EME (analogue) reports tend to be a little generous!

I discovered that the expected focal point for the RA3AQ feed was apparently wrong and this lost me several dB of signal until I corrected it to be in line with what I had discovered with other feeds. I still don't know why there is this discrepancy.

I may keep the 9cm feed on the dish for OK1DFC's 9cm EME portable expedition, next weekend. I might be able to get the transmit side working as well!

Sam


Wednesday, 5 August 2015

9cm EME

I spent a bit of time today trying to figure out how to mount my 9cm RA3AQ feed to the cage on my EME dish.
This evening I managed to mount the feed to a surplus aluminium box chassis of the right height to bring the centre of the feed in line with the centre of the dish.
Tomorrow I plan to add the 9cm LNA and feed the 9cm signals back to the transverrter in the shack through a length of LMR600 that is already installed in the duct.
This weekend has been designated as the 9cm Activity Weekend (AW) when all those with suitable equipment for the band can make contacts, do measurements and generally check out the system without the inevitable pressures of a contest or new DXCC/Locator challenge!

Sam

Wednesday, 29 July 2015

First 144MHz EME QSO


After spending much of today removing my 4/6m yagi from the mast in order to put the 144MHz yagi back up I was rewarded with my first 144MHz EME QSO! 

Almost predictably the QSO was with I2FAK. Using 200W of JT65b to a YU7EF and one of my PGA144 preamps, Franco reported my signal at -21dB and he was up to -15dB with me, averaging -18dB.

I also saw an S5 calling G0GXT and PA5Y working I2FAK.  PA5Y would have been workable although his direct signal was close to and many dB stronger than the reflected signal.

The big change from previous attempts at EME on 144MHz is that the YU7EF now has a straight dipole rather than the folded dipole that had caused me so much trouble with a poor match. I have a second to add to the array at some stage.

The moon was one day past lowest declination, so at the time of the QSO, the elevation of the moon was about 15 degrees at an azimuth of 150 degrees. I suspect lots of ground gain this time!

That is now 4 bands on which I've had EME QSOs (2m,  23, 13, & 6cm) and I've heard signals on 9cm and 3cm.
Hopefully I will add these two latter ones as worked in due course and add 70cm at some stage.

Sam













Friday, 24 July 2015

Amsat Colloquium

Mainly getting ready to go to the Amsat Colloquium in Guildford tomorrow.
Early start but that may mean braving the stormy weather due to pass over this area tomorrow morning around the time we are due to start out.........

I met up with VK5DK from Mount Gambier, South Australia, today. Colin is visiting the UK with the Victoria State over 70s cricket team. Their game in Ipswich, today, almost didn't happen due to rain. But they managed to get in a few overs before calling it a day! Colin and I had the chance to chat for an hour or so. Last time I saw Colin was in South Australia some 6 years ago.

Although Mt Gambier is actually in South Australia, the tour captain told me they designated anything east of the Murray River as still in Victoria. That way they were able to include two people from Mt Gambier.  I guess it is getting difficult to find enough players over 70 to include in their touring team!

Sam




Friday, 10 July 2015

More EME dish

Whilst writing this morning's blog I realised I hadn't updated the EME dish story.
I have now used the 2.3m dish to receive the the DL0SHF 3cm beacon reflected off the moon. I've also received JT4F signals from G3WDG at around -6 dBJT ( dB below 0dB in 2.5kHz)
This is quite good but several dB lower than I would have expected. My tracking is still being refined. 

After my initial euphoria at being able to find moon noise, later tests showed it to be a lot more difficult to find when the moon was at low declination and was close to trees etc, possibly indicating a bit more  ground noise that there should have been. Whilst the moon was at low declination I took the opportunity to change the feed for the 23cm one to check this was still working. It is three years since I last made a 23cm EME QSO! The reason being the need to move the dish to a new location in the garden after my neighbour's extension went up and blocked my moon window from anywhere west of south. No NA stations west of the American East coast..... The new location is more prominent, but gives a longer moon window.

My attempts to improve the cage alignment seem to have paid dividends as I now get more sun noise to to cold sky on 23cm than when I was last active on the band. And yes, this is taking into account the currently higher solar flux!

Sam


Transverter follow up

I have commissioned another batch of Anglian transverters from my 'assembly' man!
Of these most will be for 2m, but a significant number will be 'uncommited' boards that can be either 2 or 4m ( or any other band between 220MHz and 30MHz).

As the noise problem on 4m hasn't proved to be a big problem when beaming between east through west it has not impacted my SpE activity on 4 or 6. 
DXCC and locator scores have been steadily increasing.

I am off to the Finningley Microwave Round Table on Sunday. My intention is to take a small number of various kits including the very last one of the current batch of Anglian 144MHz transverters. I will also take PCBs and devices for sale as spares or as required. As always, I will be taking the ever-popular WA5VJB PCB antennas, covering all frequencies from 400MHz to 25GHz.

Hoping to see lots of microwavers at Finningley on Sunday.

Sam



Monday, 22 June 2015

Eme dish again

I have made a bit more progress on my EME dish refurbishment.
The dish is back on the mount and the quadrapod is also in place and connected to the feed point cage.
Thanks to G4DZU I obtained a length of flexible 4 inch ducting to carry the coax cables and DC control cables between the dish and outdoor shack. The duct has yet to be buried.
I've also managed to mount the weatherproof Storno case to a suitable bracket and to the dish support pole. The various DC cables are currently terminated in a plstic box. They will be moved to the Storno case together with a voltage converter module to 12v from 28V.
There still seems to be a lot of work to do to get the dish ready for EME.





Sam




Saturday, 30 May 2015

4m transverter

Although I haven't advertised them, I have been making 4m versions of the Anglian kit available.
Since getting back from Dayton I was determined to finish a new 4m transverter incorporating the Anglian module with one of the 30W Mitsubishi blocks. This is destined for a customer of mine.
I finished the transverter last night, just in time to take it to the Codgers breakfast this morning.

After a few tweeks to the grounding around the module and replacing the cheap Chinese power lead ( it came with a moulded plug and socket) I am now seeing over 50W saturated output. At 30W PEP the output IMD seems to be quite acceptable.

Unfortunately my QTH seems to suffer an abnormally high noise level on 4m. It is far worse on 4 than on either 6 or 2m. The noise level increases over 10dB in all directions away from due south.
I think it is time to do some serious investigating as I really would like to get back on 4m myself and I still have one of my original Nacton 4m transverters and a 150W SSPA. Nice!

Sam

Wednesday, 27 May 2015

PCB made

Well, I etched my first PCB in several years. I'm pleased to say that it was a very clean etch in spite of some reservations I had about the old sensitized Photoboard 2 (6 years old!) I had used and the two year old developer. That developer has now been ditched and a new batch made up. I' e also bought new sensitized board.

Tomorrow I intend making up the 4m 30W PA. my plan is to finish the transverter by this weekend as I want to use it in the present good ES conditions.

I had a disappointment with the Magnetic Devices 951 relay I had intended to use in the transverter. It turned out to be a 24V rather than a 12v coil............the 700R coil should have told me that!


To overcome this problem I started to look for a suitable circuit to drive the 24v relay coil from the transverter 12v supply. I did not want to use a voltage converter as there is a potential for audio frequency spikes causing interference. 
An alternative solution is to use a circuit like the K04BB all-DC circuit. This circuit charges a rather large value electrolytic capacitor to 12v. When you want the relay to operate, the charged capacitor is placed in series with the 12v supply to give 24v. Although the capacitor will discharge rather quickly as the relay is operated, the remining 12v is sufficient to hold the relay operated. 

The disadvantage of this circuit, as shown, is that it is not possible to operate the relay with a press to talk ground connection. Usually an isolated relay contact is used to apply a positive voltage to the 'trigger' input.
I didn't want to use a relay so I thought it might be possible to use an Infineon high side switch MOSFET to do the same thing, but with a ground PTT input.
I am pleased to say that this worked extremely well. I was wary that under certain conditions it might be possible to defeat the circuit by rapidly switching between on and off. I'm pleased to say that with the relay and circuit component  values that I used it was not possible to defeat the circuit!
I'll publish the circuit on my web page.
I will be making a printed circuit board for the relay circuit as my first new PCB with the resurrected PCB facility. I see this could be a very useful board for all sorts of uses!

Sam




Tuesday, 26 May 2015

PCB manufacture

Since I had an 'accident' with my etching tank around 2 years ago I have not etched any PCBs, choosing instead to have boards manufactured for me. This has been very successful but it can be expensive since it can often take three tries to get a PCB just right. Or more!

Needing a single 70MHz 30W PA board for a transverter I'm building around an Anglian transverter module I decided to ask if anyone local had a larger PA board that they weren't using. Whilst no boards were forthcoming there were several offers to etch boards for me.

However, I have decided to resurrect my own PCB-making facility. I have bought (from Rapid Electronics- surprise, everything was in stock, unlike last time I tried to order PCB materials!) a new batch of clear crystal etchant ( I hate Ferric Cloride) - too messy), sensitised board and developer crystals. I've cleaned out the etching tank and bought more chemical trays.

Tomorrow I will find out if the old magic is still there!

Among the projects I plan to have a go at are the long-talked-about 432>28MHz transverter. 
It is unlikely I will offer any of these transverters as kits ( assuming it is successful) but may well offer PCBs and a few of the more difficult to obtain parts. Please don't ask 'when?' as it is not an immediate project, but I do have a personal need for one and that often acts as the catalyst!

Sam




Monday, 11 May 2015

Dayton 2015

Getting ready to travel to Dayton later this week.
I'm travelling via Virginia, with WA1ZMS. 500 miles across the Appalachians and W Virginia before the flatlands of Ohio. 
Whahooo! one more state ticked off on my list. Virginia. That makes 36 states, I think.

I will tweet progress on my @DXing Twitter account.

I plan to spend much of my time in the fleamarket, either on WA5VJB's or WA1ZMS' stands.

Sam



Monday, 13 April 2015

144EME tests

Whilst I continue to refurbish my 2.3m EME dish I have taken the opportunity to temporarily attach one of my 9 element 144MHz YU7EF yagis on my Spid Ras AZ EL mount, using an improvised pole arrangement.
According to VK3UM EMEcalc I should be able to measure 3.2dB cold sky to sun noise at the present solar flux intensity, using my terrestrial 0.7dB PGA144MHz masthead preamplifier into my Anglian 2m transverter. The measurements were made using Spectravue in Continuum mode on my SDR-IQ at 28MHz.
I am measuring just on 3dB sun/CS with this system. I think this is pretty good for a single yagi and shows that the claimed gain of the 9 element YU7EF (13.97dBi) is probably pretty close. Of course I cannot be sure of the actual 'cold sky' temperature at this location and this can affect the measured value quite quite strongly. In the non-cold directions sky noise is about 0.5dB higher. It is gratifying that the numbers seem to work out!

  




Tuesday, 17 March 2015

EME dish drive again

Ignoring the big aurora allegedly in progress, I worked on my EME dish mount this afternoon. Auroras come and go, but good weather is rarer!!!
It never ceases to amaze me how much you can forget after just two years out of service. However, the Spid RAS motors and encoders have been wired up and seem to be doing all the right things. 
I did a rough calibration of AZ and EL, using the sun's known position ( from VK3UM EME planner) and then eventually remembered how the controller was connected, and to which COM port, on the shack desktop. With this I can use Moonsked to track various celestial noise sources, the strongest of which is the sun, of course.
Right now the dish mounting hub ( no dish in place yet) is following the sun and I can see which trees are going to require a severe pruning in the next few days!
My 'Lidl' digital inclinometer is reading out the actual elevation since the +/-1 degree resolution of the Spid encoder system is inadequate for tracking the moon with my 2.3m diameter dish at anything higher than 13cm.  Above 13cm it becomes practical, with this size dish and a decent LNA, to track on moon noise.
Altogether, I am pleased with today's progress.
Sam


Saturday, 7 March 2015

Ostermeyer Trophy

I am delighted to say that the RSGB Technical Committee has seen fit to award me the Ostermeyer Trophy for the most meritorious description of a piece of home-constructed or electronic equipment published in RadCom. I am sure there were more deserving articles in Radcom, but I am so pleased that the article on SMT for HF was so well received. I understand the kits have sold well, showing that the simplicity of the project together with the availability of all the SMD parts has persuaded so many to have a go at SMD construction.
I will be at the RSGB AGM in April to receive the trophy.
Thanks RSGB


Wednesday, 4 March 2015

EME mount

It was warm enough today (10C) that I could move the pallet mount to its new position in the middle of the lawn.
This is the same mount I was using several years ago for 23 through 6cm EME. 

After considerable discussion with G3WDG I have decided to go with linear polarisation on 3cm, so I can use my Chaparral feed, which is well suited to my KTI prime focus dish. It is easy to change from vertical to horizontal polarisation with the way I have arranged the focus box in the cage.

I have been promised a potent SSPA but I'm still waiting for the DL/PA0 LNA.  In the meantime I will probably try my Octagon LNB-based LNA in front of the frequency-locked DB6NT G3 transverter.

The biggest challenge is still going to be tracking and I'm going to try a simple system used by both G3WDG and G3LTF. This system combines moon noise tracking with a tweakable auto tracking arrangement. The Spid RAS tracking system will be uncoupled and used only for approximate position indicating when on 3cm.

A remote digital inclinometer gives absolute moon elevation as a back up and confidence booster.

I hope to re-install the 23 and 13cm system on the dish in due course.



The moon can be seen in the eastern sky to the right of the Spid RAS positioned.




Monday, 2 March 2015

Beacon update

The 1Ghz low noise PLL clock has been assembled into a surplus HS400 case with a 1GHz distribution amplifier featuring 4 outputs for future beacon expansion.
The Toslink NMEA drive to the DDS unit is being prepared, ready to connect to the indoor unit.
Today it was found possible to retrieve the G3RUH GPSDO from the BT Martlesham tower. It has proven rather difficult to liberate the GPSDO so that it can be interfaced, but at least it has been done!
More info on the 3cm beacon progress in the near future.


Friday, 6 February 2015

Beacons

After the Martlesham 23 and 3cm beacons failed a few weeks ago my thoughts turned to upgrading the 3cm beacon, once again.
The 23cm beacon, GB3MHZ, was quickly returned to service, no fault found (FNF), but the 3cm beacon was taken completely out of service.
Two faults were found.
One was that the driver output was down and that could explain the reports of poor signals levels for the last year or so.
The other fault was more serious. The RDDS had failed. The result was that the beacon was no longer locked but had defaulted to the bottom end of the VCXO range, giving an output around 10368.780MHz
At this point it was decided that the beacon should have a complete rebuild and incorporate MGM ( digital modes) at last. For the last few years the beacon has been running frequency locked but with FSK keying and plain carrier only.
The other big change was that the group decided that we should adopt the Danish Next Generation Beacon (NGB) platform. This is well developed and supported in Europe. In addition to running the Danish developed PI4 digital mode, it is easy to change the mode to one of several others as conditions and  bands dictate.
A DDS board and a 1GHz clock board were quickly ordered and have arrived. The clock board generates the required clean DDS clock and can be shared amongst all the other bands, if required. The clock board is driven by our G3RUH 10MHz GPSDO. NMEA output from the GPS time locks the digital mode sequence.
Each new band will require a new DDS board. We are thinking about 13cm next. 
The photo shows the DDS board in its screened box.








Friday, 23 January 2015

Moon bounce muses

I was last on EME ( apart from some listening on 2m)  2 1/2 years ago when I made my last 23cm EME QSO.  I did operate briefly on 6cm EME in July/August 2012, just before EME2012. I wanted to work the TM8PB Plumier Bodeau set up, which I did ; and several more besides. Since then, zilch. Nada.

I had to remove my dish when my neighbours erected a large extension along our property line, well down the garden, and effectively cutting off anything beyond SSE from the dish.
Not good and not much I could do about it. At least it made a good location for a lean-to greenhouse!

Since then I have agonised over where in the garden (lawn) I could get away with re-erecting the dish and mount. I believe I have located a good position ( and my neighbours can still get the full benefit of looking at it).

I am waiting for the weather to warm up before I start to prepare the ground for the pallet mount. I also need to dig a trench for the cable duct. Right now the ground is still a bit hard.

Having got the dish back in operation the question is which band(s) to activate?  Long term I really want to try 3cm and to that end I have already started to collect parts. Realistically, I suspect that my operation will be using JT4F as I will be power-limited to around 14W, using a surplus SSPA and the 2.3m dish.
I have one of the new DL3BLC ( I hope I have Ron's callsign correct....) 0.65dB LNAs on order and a back up under construction. Similarly I have a new feed under construction.

I suspect I will opt to bring the 23cm EME system back on line first. Since I was last QRV on 23cm EME there has been a noticeable increase in activity on the band (I know, because of the number of VLNA23 preamps I have sold to potential 23cm EME ops!).

I am also tempted to resurrect my 13cm system as my dish really worked well on that band and I would like to try 2300MHz since I was one of the team that pushed for its inclusion in the recent OFCOM changes to 13cm and 9cm....

And of course I have a complete system for 9cm EME that has never been tried, other than on receive, so that ought to be given an airing. 

So, there is lots to do and few excuses other than laziness to stop me getting on with EME,  now my interest has been piqued again.

Last week's visit to Dwingaloo has a lot to answer for. 

Let's see how this all pans out.......

Sam



Saturday, 3 January 2015

Moved the shack indoors

Now that it has become increasingly difficult to keep the garage shack warm enough to be comfortable, I have moved the main rig back indoors and using the coax cables between the two shacks to allow me to keep the transverters and PAs in the outside shack. The six wire control cable is used for PTT and for bringing remote meter readings back to the indoor shack.
One innovation this year has been to combine the K3 28Mhz IF transmit and receive with an MCL BNC combiner in the indoor shack, at the back of the K3. In the outdoor shack I've put another (SMA) MCL splitter inside the Anglian transverter to split the 28Mhz IF back to transmit and receive, again. This way I use just one cable, at 28MHz, for the RF path between the shacks.
The second, lower loss, coax can be used for another IF! e.g. for the 23, 13 and 3cm bands using the K3 or another rig.
Rotator control uses my ERC controlled Yaesu G1000DXC, over the home WiFi network and outside shack PC.



Sam