Persistent cough

Whatever the bug is, it is persistent. It just won’t clear. It seems to be very common, as well. I hear a number of people reporting a similar problem.

Hopefully, not too much longer.....three weeks is long enough.......

I have managed to do a bit more observing of the Es’Hail-2 satellite and further optimised my receiver. I still can’t get a good comparison with the beacon reception by other amateurs as each seems to have a different set up and hence way of making measurements on the 10706MHz engineering (broadcast) beacon. The problem seems to relate to making a measurement in the beacon centre carrier level in a known resolution bandwidth. Simple  you’d think? A number of levels have been given for signal level, but without resolution bandwidth these are meaningless.

This morning I decided to have another look. The engineering beacon centre frequency has always sounded ‘rough’ and showed several ‘carriers’ within the narrow passband I was looking at. This is with the LNB I had modified for external 25MHz reference input. It just didn’t ‘feel’ right. That radio engineer’s feeling for a signal? Not knowing whether the engineering beacon actually had some form of data modulation, close to the carrier, it was difficult to tell what was going on. 

As a test I set my RF Explorer signal generator to 10706/4MHz and connected it to a WA5VJB LPY antenna. The resulting forth harmonic showed quite strongly on the SDRUno display and with the same ‘data modulation. It was now clear that the external locking on the LNB was not working as intended.  As an aside, the TCXO in the RF Explorer showed within a few hundred Hz of the beacon centre frequency. 

I have a spare,  unmodified, Octagon LNB (27MHz reference version), so I substituted it for the modified one and looked again at the beacon. Now the beacon  centre frequency was clean and sounded it on the headphones. 

I’ll waterproof the system again, later, and remeasure signal levels.

I have a spare high performance 10GHz LNA and horn feed system. I am going to look carefully at using that for the satellite in preference to the LNB. Although that is a cheap approach, I am beginning to wonder if the noise figure will turn out to be too high, down at 10489MHz?

I’ll need to use my spare DB6NT transverter and the feed/LNA and an IF at 265MHz

The Minitouner will tune into the required frequency range, so no need to worry about that.

Happy New Year

IC9700 thoughts

Apologies for no posts for a few days, but I’m recovering from a rather nasty viral infection, caught last weekend, and which is only slowly responding to doctor’s orders! I’ve not been anywhere near the shack for almost a week and the time has allowed me to reflect on what I expect of the new ICOM 9700. 

Two and a half years ago I purchased an IC7300, more in hope than expectation of a good, useable, design. I was most pleasantly surprised at how good it is, especially as a K3 with all the bells and whistles owner and user. The IC7300 turned out to be, for me as very part time HF operator, a far more user friendly rig than the K3. Undoubtedly the K3 scores well on many points, and although I know personally that it has much VHF and microwaver input to increase it’s appeal to upper bands amateurs. Its range of transverter interfaces is unmatched, with easy (too easy?) access to a wide range of  level, frequency and offset adjustments and a superb IF interface facility.  But that P3 is nothing short of useless for anything serious and although I have installed the SVGA interface, I don’t see any significant overall improvement compared to using an SDR-IQ as the ‘go to’ spectrum and waterfall display and it has the advantage of ‘Continuum Noise’ measurement when used with Spectravue which the P3 doesn’t offer. If you haven’t used this measurement you can’t be a serious radio ham!!, we won’t mention the awful encoder interface on the P3 beyond could Elecraft chosen anything worse? Yes, there are ways round all this, but I want a self contained radio that doesn’t need a PC/laptop and a 27inch monitor on my bench just to see that weak signal in the noise.

The Internal 144MHz transverter is poor. I will leave it at that. A well-known UK amateur had a far more descriptive suggestion.

No, the IC7300 is not a panacea. The German transverter interface had a major problem that was slow to be acknowledged. I’m told it’s now been sorted. I’ve not revisited it. I reverted to the good old power attenuator solution.

Given all this, why am I looking at the IC9700?

First  let me say that I have some reservations about the design and these will only be resolved once I manage to get one on my bench. 

Living as I do on the east coast, I have a few unusual conditions to contend with. On 23cm I am very close (<5km) to the GB3MHZ Martlesham 23cm beacon. When I borrowed an IC910X, some years back, and first tried it on 23cm, it was completely unusable. The phase noise from the IC910 Lo (VFO) was so poor that reciprocal mixing from the beacon was apparent 700kHz away in the usual DX frequency area of the band.

When the North Sea path opens up Belgian (in particular) radar can be rather strong. Most rigs have a noise blanker than can cope with the noise. It is not like car engine ignition or an electric fence. The radar beam sweeps past and produces multiple pulses and these are very often accompanied by forward reflections from objects out to sea (and maybe reflections from inland objects) that add together to sound like a buzz. Some rigs (like the TS2000x) can cope rather well with this, other fail miserably. This will be a severe test for the IC9700.

Another problem is likely to be on 144MHz where I have a number of well placed, adequately ‘endowed’ EME stations in the surrounding counties. The K3, with an Anglian transverter, copes quite well. The TS2000X (which always needed a masthead preamp) did not. 

So, what am I waiting for?

I’ve read (re-read) the specs, asked questions of the manufacturer’s representatives at Dayton, Friedrichshafen and in the UK and not (no surprise there then) gotten the answers I wanted. So now I have decide that the price is just about affordable to buy one and see how well it copes at this QTH.

I believe I have the experience from being the designer of many transverters for all of these bands to make sound judgement on performance and to write up my experiences on my blog.

I’ve paid my deposit and now I wait..........

Sam

Iceni v1.1 - another view

The new board in its housing

100mm x 62mm x 40mm

Sam

(Backup) Iceni V1.1

I finished my tests on the new PCB for my Iceni 70cm transverter. The mixer upgrade to version 1.0 boards required a cut and strap modification. Whilst easy to do it didn’t look too nice. My new V1.1 PCB incorporates the mixer upgrade and fixes a couple of small track breaks. I ordered a few boards for test,  but now I will have to order more boards for issue with future Iceni kits.

All tests on the transverter were successful.

More Es-Hail-2 LNB tests

Having been diverted onto other things for the last few days, I thought I would take advantage of the wet day (here) to finish routing the IF cable round my shack, install SDRUno on my shack PC and connect the LNB IF lead to the RSP2 Pro.  First problem....the RSP2Pro internal bias tee is only 4.7V and I need closer to 13V. Solution was to use a temporary external bias tee.

Tuning to 1008MHz and the dish pointed at the 28E slot, the 10MHz wide dispersion (span) of the RSP shows a big signal from whichever digital channel it is on 10758MHz on vertical polarisation.

Tuning between stations shows a big drop in signal level. 

Now to do some definitive tests on cold sky to ground, sun (if I can manage to point at it) and satellite noise floor. Until the Es’Hail-2 amateur transponder is activated these tests can only be indicative. 

Problem 2.  There is some concern about the OTSLO LNB internal waveguide size being too small at 10.450GHz,  causing excess loss and consequence higher noise figure.  There are claims that the horizontal probe may be further enough away from the backstop (rear short circuit) that the loss may not be so high and it may therefore be necessary for me to turn my LNB 90 Degrees to use that probe. That has some implications for weatherproofing. More testing required.

Sam

LNB cables

I had an interesting problem with the Es’Hail-2 satellite LNB. Actually, not so much the LNB as the cables.

I have been running the LNB IF over the supplied 75R ‘white’ cable. This is not quite long enough to reach to the selected position of the Minitoiuner. On the other the 25MHz reference runs over a much longer RG58 cable, but only to the rack position of the Leo Bodnar Mini GPS source.

In order to close the shack door and generally tidy up the cable runs, the cables have now been brought into the shack through the wall gland cable entry. Because of the incompatible cable lengths decided to swap over the functions of the two cables. The shorter 75 R IF  cable now being used for the 25MHz reference and the longer RG58 now the IF and LNB power cable.

Although the Minitoiune display showed a strong signal, it was clear from the phase constellation that the software was struggling to obtain lock. I couldn’t get a picture from Freesat.

Swap the cables back, temporarily, and all was well again.

With the high gain of the LNB the Minitoiuner should be OK with the much longer IF lead. I changed the reference drive level over quite a large range with no success, just in case. 

Could the reference be objecting to 75R cable or was something else happening? I decided to reset the 25MHz reference drive level and use another  50R coax  cable reference  able connection to the LNB. This worked absolutely fine. 

I really am not sure whether the problem was down to impedance or to cable loss (at 25MHz?). However, I will replace the crappy white 75R stuff with a length of RG58 tomorrow and see if all is still OK.

Entertaining times!

Sam

LNB received

Second Octagon LNB received. Now to open it and check which reference it uses. 25 or 27MHz. 25MHz I hope!

Note that this one has 1301 rather than 1309 on the label, as was expected.......opening it is the only option to if I want to be sure.

And, very disappointed. 27MHz reference. Apparently I misread the online data on LNBs and it was actually another 1609 that I needed.

I won’t be able to try the tests I wanted on this one and as the ordering process seems to be pretty random, I don’t feel inclined to order yet another one unless I can specify it as a 1609.

I did try to use my FT817 to listen to whether the reference was 25 or 27MHz. Even with the antenna on the 817 very close to the LNB I could not detect any carrier at either frequency. There was a tremendous amount of digital ‘hash’ however.

I eventually opened the LNB (carefully) to check that it did, indeed, have a 27MHz crystal (in fact two) and the 3560 PLL chip.

Sam

LNB info

DG0OPK.darc.de has details of the Octagon LNB with the 25MHz single crystal that I use in my LNB for Es’Hail-2 satellite system. This is supposedly the low cost LNB using the RT320m PLL chip in the OTSLO twin LNB. It looks like there is lots of info on this LNB and others on the uhf-satcom.com web page links. 

I did notice that a lot of the published info, on modifying these LNBs, refers to the version with the 27MHz crystal. Apparently, several of these have two  crystals and two PLLs. The Octagon PLL LNB i have only has the one crystal (25MHz) and it easy to modify. The first visible difference, inside, is that the ones with the 25MHz crystal has red solder resist, whilst the 27MHz version has green resist. Of course, this doesn’t help from the outside!

I haven’t checked but the 25MHz ones (which might be the ones you can drive with a 24MHz reference for a better (higher) IF) have a code 1609 instead of the 1306

It’s all a bit of a minefield when ordering!!!!!!!,

Further Progress on Es’Hail-2 system

As mention on my Twitter (DXing) account, I have planted a 3inch diameter, 6 foot, galvanised pole in a 2 foot deep hole near the shack. The hole was back filled with 10mm gravel (from Homebase at £2.50 bag) and then top soil on the top of that.

My 90cm Channel Master offset dish is attached to its original az/el non-motorised mount. I’m glad I didn’t through that out!

I had to fabricate a new saddle top to hold the LNB as I’d lost the original and besides the 40mm diameter LNB would not quite fit the original clamp.

.

Currently I can easily swing the dish between 28E and 26E. The Freesat TV at 28E is very strong here in East Anglian, using the 90cm dish. The 26E signals I can see might be from BADAR, but I need to check this.

I need to connect my SDRPlay RSP2Pro to the LNB output and check what the noise is like at 739MHz (The IF from the LNB when receiving the Es’Hail-2 amateur narrowband (voice/data) signals. G8DKK has suggested an attenuator will be required. This will cause a problem as I intended to use the RSP2Pro internal bias tee to drive the LNB. As it happens, the 4.7V output from the RspPro2 is too low for the LNB, anyway, so an external bias tee and 12v supply for the LNB are required.

Sam

Es’hail-2 receive system

Since the successful launch of Es’hail-2 satellite I have brought my Ku band LNB out of its hidey hole  and proceeded to check out the modifications I had done previously. I had previously opened the Octagon PLL LNB and performed the G4FRE  version of the external reference modification.

Dave used one of the two F connector IF outputs as an external 25 or 27MHz reference input. This IF output can no longer be used as an IF output, of course. The remaining IF output being the only one now available.

Dave’s modification is described in the September 2018 BATC magazine (well worth the membership fee).

The modification involves opening up the LNB and cutting a track. A 1nF ceramic capacitor is then soldered between the pad where the IF connector a appears and the nearer of the two crystal pads. A short wire is required if a 0805 SMD capacitor is used. I elected to use a bigger 1206 size capacitor and cut the track further up so that I could bridge the gap between the required pads with the capacitor. In the event I still needed a very, very, short wire to complete the gap. Why do it this way? Dave had commented that he had observed some instability and had to reroute the wire. I haven’t observed any instability doing it this way.  I may just have been lucky.  One other comment is that I did seem to require a little more 25MHz drive, at -4dBm, but that might be due to using a longer RG58 coaxial cable to get from the external 25MHz source to the LNB.

Two versions of the Octagon PLL LNB seem to be available. One uses 27MHz reference, and may be an older version. The other one uses a 25MHz reference.

As my stable reference source I used a Leo Bodnar GPSMini. This can produce too much output. I used mine at 8ma drive (the lowest setting) and then a 3dB attenuator before connecting to the coax cable at -4dBm.

Replacing a standard DRO LNB, that had come with my 45cm dish and tripod (described as a caravan system on eBay), with the Octagon PLL LNB, the Sky and Freesat digital satellite TV signals were indicating about the same signal level on the MiniTouner receiver. A weak 10.4896GHz signal from my sweeper, radiated by an WA5VJB LPY antenna connected to the sweeper output, produced a very respectable signal on my spectrum analyser connected to the LNB, and tuned to 739.5MHz,  as the IF.

My  next stage is to ‘plant’ a 3inch pole in the garden and then mount my 90cm Channel Master offset dish on the top of it. The CM dish mount is designed for this size pole. The LNB will attach to the dish 40mm clamp.

739MHz IF output on my analyser

Preamp builds

The last few days have seen a flurry of preamp building. Following The DX Shop decision not to supply built VLNAs I have had a number of (nice!) requests to build kits for those who either felt unable to cope with building an SMD kit with 0603 size parts, or who don’t have the equipment to align the VLNA for lowest noise. As I am not set up for production of built preamps, it has taken a while to get round to clearing my backlog. I still have a few ‘specials’ to build, but these should be done soon.

I have a new batch of solder paste and this is producing nice results with my BetaFlow reflow oven system. The results have been consistent and little rework has been necessary.

The picture below shows the results of measurement on the most recent VLNA23.

I might even get round to building one for myself.......

Sam

G4DCV

I was able to briefly visit with Paul and his lovely partner,  Miranda, on my way back from Heathrow, earlier this evening.

I had a video item to drop off. Some of you may recall does a lot of the RSGB video work.

Paul and I had a nice chat about our earlier days in amateur radio.

A most enjoyable visit to the Berkshire/Surrey borderlands.

Sam

Building preamps

I was asked to build another 1694MHz range VLNA for a customer who wanted a more weatherproof version of the  VLNA. I am in the process of mounting the VLNA in a small ABS plasic box (box within a box) with the input connector accessed through a hole in the box and the output connector cabled to the VLNA from a bulkhead SMA. This has been an interesting exercise in weatherproofing......

Sam

Spectrum Forum

I’ll be heading off to London by train in the morning. I am representing the UKuG at the RSGB’s Spectrum Forum meeting.

My report on the Group has been submitted.

I used to represent the Group then the new, incoming, Chairman took over. That has continued for the last few years, but he was not available to attend this year.

As the current Chairman I felt it was advisable someone from the Group should attend, but I was not particularly looking forward to it......... I struggle to understand what it actually achieves. Maybe it will be clearer after tomorrow?

My first trip to London in over a year.

I won’t be reporting on the content as it is RSGB business. A report from RSGB will, no doubt, be forthcoming.

On a very sad note, I hear that Will Jensby, W0EOM, has passed away. Will was a microwave legend. I am pleased to say that I met and chatted to him on many occasions at events in the USA.

No history of USA microwaves would be complete without mention of the contributions made by Will.

Vale Will

Sam

PSUs

I went to Rapid Electronics with G4FSG this morning. They have 12V 12.5A (150W) PSUs in their clearance sale at £22.50 plus VAT. That TDK Lambda SMPSU operates from 85 to 230V AC input and is therefore suitable for powering my 10GHz EME SSPA, out at the dish. I have a 115V transformer isolated supply at the dish.

Graham picked up a nice Meanwell 12V/40A supply at a really good price. It was the last one.

Sam

10GHz amplifier

I have been mulling over what to do with my 10GHz SSPA. It needs 11V at what I though was about 8A. It turns out that the quiesent current is nearer 10A and the peak drive sends it up to about 12.5A.

I didn’t want to use 28V to drive the Melcher DC-DC converter to produce the 11V. 

G4FSG pointed out that Rapid Electronics are selling their remaining stock of TDK Lambda PS150 (150W) power supplies for £22.95 +VAT. That has to be worth a trip down to Colchester tomorrow.

The  12V version is variable from 10.5 to 13V at 12.5A and can be run from 110 to 230V AC, so I could run it at my dish from the yellow builders transformer that supplies a ‘safer’ 55-0-55V AC out at the dish. 

The alternative is a Nissei NS1230M variable PSU that gives 20A from 4 to about 16v from110 to 230V AC. These PSUs are £89 from Martin Lynch and Son.

I have been active on 2m FT8 again this evening and worked some nice DX including down into northern Spain, once again. Conditions seem quite good on 2m at least.

Sam

Interesting problem

I had planned to use 3cm during this evening’s UKAC.  Trying to work G4BAO I was informed that my LO was unlocking. On investigation I found that the 106.500MHz reflock, located in the shack and fed by 10MHz from my Z3801 GPS disciplined source, was responsible. 

I quickly set up my Leo Bodnar dual output GPS disciplined source on 106.500MHz and fed the LO signal up to the masthead transverter. Checking with G3XDY, he reported the signal sounded OK and looked acceptably narrow on the spectrum display.

I may ditch the reflock, as the HS400 it is housed in takes up valuable space in the shack rack. A LB miniGPS would take up much less space in or on the rack. A 1575MHz GPS antenna signal distribution system is beginning to look necessary.

A second problem was confirmed . The 10GHz transverter is definitely down in sensitivity. This could be the dreaded LO ‘dying FET’ syndrome that occurs with the DB6NT G2 transverter when it is left on all the time, as mine is, at masthead. Leaving it on keeps the box warm and I don’t suffer from condensation in the box. Another job......

Sam

Hunter’s moon approaches.

Still testing

Trying blog touch pro

Apparently the original Google Blogger app has now been withdrawn. I am trying a few other apps. This is Blog Touch Pro.

The photo is to check that I can send photos. My previous attempt didn’t allow me to delete the wrong photo!

Fail.....

It looks like it still lives!

Still exploring what is what on here. If all is well the blog will be back. My intention is to continue with comments, observations and information relating to my VHF, UHF and microwave band activities.
If anyone is still checking my blog, please comment so that I know I’m not ‘talking to myself’!

Sam

Back again

I am exploring whether my Blogspot blog is still operative. Let’s see what happens before I write much else........ Sam