Wednesday, 25 June 2014

French air traffic controllers

Just learnt that the strike will end in the morning, so hopefully our EJ flight to Zurich will be on time!
Looking forward to the weekend in Friedrichshafen, seeing the new gear on sale as well as the surplus bits, but most important, looking forward to seeing old friends from across Europe (and beyond).

pro 3 update

An interesting discovery. The power output control on the Pro3 also controls the transverter output level. I never expected that, but it has enabled me to get a little more output on 10GHz by increasing the 28MHz drive level.   Simples!!



Getting ready for tomorrow. Flying (I hope) from Luton to Zurich and then train and ferry to Friedrichshafen. However, I am concerned about the delays on many European flights due to the actions of the French Air traffic controllers. It is amazing just how much European airspace is controlled by the French. Yesterday's Zurich flight arrived mid evening and would have caused us to miss the last ferry. Hopefully, it won't happen tomorrow as Easyjet wises-up to what flights, to where, will work and what won't.

There is a quite a large contingent going from East Anglian, using the Luton/Zurich/Romanshorn/Friedrichshafen route, so there is some scope to do car rental etc if flight delays cause us to miss the last train/ferry. I hope it doesn't come to that.

I am very much looking forward to seeing some of the new gear on show at FHM. And buying all those bits I don't really need, but do, because I can!

As usual, I will be donating a prize to the ARI EME Contest organisers. I am not really sure how this began, but it seems to have become a tradition.........this year I have decided to donate an Anglian 144MHz transverter kit. I hope it is appreciated.
I'll be at the QSL wall at 1pm local on Friday for the usual EME meet-up.


Tuesday, 24 June 2014

Plumbing the Anglian

I wanted to use my Anglian 144MHz  transverter with my ICOM Pro3, as the 28MHz IF. The problem was that the Anglian was designed with a K3 in mind so has separate transmit and receive IF ports.
Since the Pro 3 only produces around -20dBm IF output (typically ICOM) there was also the problem of  whether there would be enough IF drive, especially with another 3dB loss due to the MiniCircuits IF coupler.
The first tests were encouraging when the receive noise level came up significantly on the Pro3 when the transverter was connected and the transverter port activated.
I found I could get about 40mW 2m out of the Anglian with full -20dBm, 28MHz drive. Removing the two  parallel 120R dump resistors and placing a 10R across the 100R in the input attenuator I could bring the 144MHz output power back up to 100mW. As the Pro 3 transverter output is quoted in mV I assume the output impedance it wants to look into is not necessarily 50R?
100mW of 144MHz IF is just sufficient to get to about 7 W output from my 10GHz transverter, with the current setting. When I next take the 10GHz off the mast or luff it over, I will increase the transmit gain to compensate.

I'm now looking forward to the UK AC on 10GHz this evening. I'm also hoping Englnd will have won their last World Cup match as well!


Monday, 23 June 2014

A bit of 10GHz

What's going on?
First Peter, G3PHO resurrects his 3cm gear and works Neil, G4BRK. John, G4BAO works Neil, then Graham, G4FSG and I have a QSO on 3cm. Both of Graham and I have recently put our 10GHz systems back into use.
Unfortunately I didn't manage to work Peter, whilst Neil and John had to go QRT. However, I hope to be on for tomorrow evening's UKAC on UHF.

Maybe a bit of resurgent interest in 3cm?
I will try to get my ICOM Pro 3 and Anglian transverter on in place of the FT817 tomorrow. The spectrum display will be very useful, I think.


Saturday, 21 June 2014

New ones on 6m

No one could ever accuse me of being a 6m band fanatic. But when the Es season comes round I do get enthused about what I can work on this glorious mode.
Taking advantage of today's 6m contest and some quite intense Es conditions I was able to add a few new DXCCs to my growing total.
Today I added Gibraltar, Macedonia and Andorra. None of these could be regarded as exotic and indeed all are within that first reflection range, so should have been worked previously, but somehow I had missed them!
My total is now 57 DXCC entities and 203 locators.

My station on 6m today was  80W from my K3 and a 5 element 6/4m dual band YU7EF yagi ( courtesy of G4ERO). Alternatively I could have used the ICOM Pro3, which I rather like as a 6m rig. 

There won't be any new ones tomorrow as I am off to RAL at 06:30 in the morning and not back until mid evening..............


Friday, 20 June 2014


Getting bits ready to take to the Rutherford Appleton Labs (RAL) Microwave Round Table on Sunday. It clashes with our own local ESWR ( Ipswich) rally, but I had already made arrangements go to to RAL when the date of the ESWR was announced. So RAL it is.
I will be taking the usual VLNA preamps, PGA Amp kits, MAR6 kits as well as a selection of Kent's PCB antennas.
In addition to these usual items I am going to take a small batch of Nacton 4m transverter kits, Anglian 2m transverter kits and some PA/LPF short kits.
To round it off I will take some coaxial couplers, SS coax switches, and isolators. These are the remaining items from G4PBP's estate.
If anyone reading this is going on Sunday and wants me to reserve any of these items for them, please let me know. Several items are already reserved. He who hesitates loses..........

At this time next week I should be in Friedrichschafen with G4BAO, G4FSG, WA5VJB and G4CBA, French air traffic control strikers permitting! 
More about this next week.

73 de Sam

Sunday, 15 June 2014

More 10GHz tests

I substituted a three ring Chaparall feed and  DEMI 10GHz preamp (W5LUA) coax preamp into my DB6NTG3 transverter. Power was fed over the receive coax.
At the shack end the bias tee injected 13.5V.
One of my Anglian 144 transverters brought the signal (noise) down to 28-30MHz.
My SDR-IQ was then tuned to 29Mhz and dispersion set to 100kHz.
Using this set up I was able to measure 3.8dB sun to cold sky and 1.9dB ground to cold sky.

According to EMECalc these numbers are self consistent with the gain of the dish and type of feed, system noise figure of 1.2dB etc. at an SFI of 129 ( given for today) so I am quite pleased with my initial tests. 

The three ring Chaparall feed only gives, according to VK3UM,  45% feed efficiency. I know this can be improved upon so the next stage may well be to try and obtain a decent circular polarised horn feed for the dish, followed by an increase in dish size to 1.2 or 1.4m


Saturday, 14 June 2014

Sun noise on 10GHz

I have temporarily mounted my 'old' Channel Master 90cm onto the EME mount, since I hadn't got round to reinstalling the 2.4m dish.

Using a standard Ku band LNB into my spectrum analyser at 1256MHz IF I was able to do some testing.
I now know that the correct elevation in between 23 and 23.5 degrees. I measured the max noise from the sun and then checked the angle that the elevation frame pointed and the elevation angle of the sun at that time according to VK3UM EME Planner. My measurements average just under 23.5 degrees. I later found that the Channel Master 1.2m dish shows 23 degrees. I suspect I am not far out!
I also noted that for maximum noise the shadow of the LNB saddle should be aimed at the base of the bottom tripod stay.

This is clearly shown in the second photo.
Anyway, the average sun noise to cold sky measured 7dB at a solar flux of 153. This compares with an indicated number of about 6dB using VK3UM EMECalc at 10.368MHz. I would expect a few tenths of a dB more at 11GHz.
Of course the VK3UM results depend on what assumptions you make!
In this case 0.65dB noise figure with no loss ahead of the LNB and the feed is a linearly polarised Chapperal three ring.


Monday, 9 June 2014

10GHz update

Having replaced the IF RG58 the transverter is now working well.
I get a good signal from GB3PKT at St. Osythe.
I believe I am not on the main lobe from the beacon antenna, so the strength of the signal is moderate. It's probably ideal for propagation monitoring. The amount of rain scatter on the beacon, earlier this afternoon, suggests this will be a useful feature during heavy rain. There was a storm out Essex way. Not much rain hereabouts.
Now to investigate the effect of the two wind generators that that have been installed a few hundred metres east of this QTH!

Sunday, 8 June 2014

10Ghz part 2

I temporarily put the 10GHz transverter on the mast this afternoon. I was surprised at how little the 144MHz receiver noise level increased when it was powered up. On further investigation I found that the locked 106.5MHz LO from the shack was delivering only around -5dBm at the transverter LO port. From previous measurements the DB6NT G2 needs typically +6dBm. The loss of signal turned out to be in the 20m of RG58 coax from the shack to masthead. What is more the second cable carrying the 144Mhz IF had even more loss! Those rodents again?

I think both cables need to be replaced although the high loss of the LO cable has, for now, been overcome by adding a PGA Amp in the LO box in the shack. That delivers +20dBm to the RG58 coax and +9dBm to the transverter. This is not ideal practice, but will do for the moment.
It certainly explains why the 3cm system had become progressively more deaf until I took it out of service two years ago.
I think I will replace the IF RG58 with LMR400 as the IF signal has to be routed on to the indoor shack. Even more loss!
Progress at last and maybe QRV on 3cm from mid week!

Saturday, 7 June 2014


Having reached my initial target of 200 locators on 6m I thought I would take a break for a few days and have another go at getting the 10GHz transverter system back on air.
What I didn't expect was that the DC feed that powers the 10GHz system at the top of the mast would take so much effort to bring it up to scratch. I have a Manson 13.5V PSU in the garage that is turned up to give +16V to mast head. The masthead 10GHz transverter has internal 11V and 12v  linear regulators, so I can allow for a small voltage drop at the maximum 8.3A that the transverter takes at 10W out.

When my etching tak was accidentally tipped over several months ago the enchant went everywhere, including on the PSU.....
Fortunately the damage was not too bad and only the thick DC leads and connections suffered significant damage.
I have now replaced the original connections with 50A PowerPole connectors. I don't need 50A. 10A is sufficient, but the thick mast-feeding wires (8mm audio cable) won't fit into the standard (30A) Powerpole connector receptacle.
I have also incorporated an in-line fuse holder with 10A mini blade ( auto) fuse. This should have been done long ago, but I relied on the short circuit protection inside PSU. Not good practice!
Another idea I have is to use one of G4HUP's High side switches to be able to turn the 16V on and off remotely with a simple logic level output from my remote USB 8 channel relay.

Finally, with the Powerpole connector, I can now disconnect the masthead system from the shack PSU when the are storms around.  Something I could only do previously with some effort!


Thursday, 5 June 2014

Those CB radios

Seems that both radios work exactly as they should and that after being almost 50 years old!
Don't ask me how I know they work.
However, I am amazed that after all these years they still do what it says on the tin.
The receivers are super regens and they make one heck of a racket all the way up to 50MHz, judging by the noise increase on the P3 connected to the K3 when the CB receiver is switched on.
The power output is difficult to measure, but I suspect it is less than 100mW. The output transistor is a small ceramic device in a package not unlike the BFR91. 1965 technology.

Close examination of both transceivers shows they are in excellent condition after all this time. The leather cases are in good condition and even the telescopic aerials are undamaged. Remarkable!

Time to carefully stow them away with the rest of my growing collection of hand  held 'walky talkies'.


Wednesday, 4 June 2014

Retro radio

When does radio become retro?
I've never been particularly enamoured of vintage radio. AR88 and CR100s have never appealed to me.
I was introduced to two-way radio communications during the first wave of CB in the UK. I have to add that I never actually broke the law by transmitting speech on 27Mhz, but I did often hear American CB'ers voices emanating from the various 27MHz radio control receivers I built. Particularly in the early 1960s. I did have a radio control license.


Later my friends bought and used 27MHz walks talkies. I lusted after one of these but could never afford one. Those pull-out telescopic antennas ( less than 5foot to qualify for FCC part 15 unlicensed equipment) and the snugly fitting leather cases just looked the part.

Recently my local antiques shop in Felixstowe included a pair of beautiful Radifon SRT-602 27MHz walk talkies, in their original leather cases no less, for £20/pair. The boiler plate on the rear says made in August 1965. The cases are metal ( no cheap plastic here). They take a 9v PP3 battery. There is no sign of battery corrosion in either unit.

After several weeks of passing by the shop on my way into town I decided I really ought to buy them before someone else with a similar fetish bought them!
I eventually agreed £18 for the pair and carried them home.
I have no intention of using them. That would be illegal. However, I will check them out on my spectrum analyser and signal generator.
It says 6 transistor, 11channel on them, but I believe that really means they are on the old FCC channel 11 as there is no provision for a channel switch or even space on the PCB for more than one or two crystals.
I will publish a bit more about them after a few measurements.

Sunday, 1 June 2014

Nacton transverters again

I have decided to launch the Nacton 4m transverter again.
I still have boards left over from the first two runs and enough tuneable coils to make it worth doing whilst we sort out the Anglian 4m transverter. This frees up Anglian boards to meet the demand for 144MHz transverters!
One difference will be that the Nacton short kits will be a little 'shorter' than the first batch, but in turn will be a bit cheaper!
There will be more info on my web page shortly.
I still have lots of both 4m and 2m PA/LPF short kits as well.
I have now heard a number of Nacton transverters on air and they sounded fine. That partly persuaded me to do the re-launch!