Astrophotography during the Perseids

OK, so not quite amateur radio or electronics, or is it?

Last night myself and Sam stayed up late and camped out to watch the Perseids meteor shower. The best of which seemed to come just minutes after we started observing at about 22:00 and in fact before the sky was fully dark. We saw some excellent meteors, including one that Sam sadly missed that left a very long lingering smoke trail.

At about 23:00 I started the SLR taking 30sec 18mm f/3.5 ISO1600 exposures, with a 15sec delay between each. Out of around 90 shots, three show definite Perseid meteors. One of them actually might show two - but something knocked the camera during exposure! It also has three satellites in that shot!

The picture above is the clearest Perseid captured. Sadly my skies are not as dark as i'd like them, and at 30sec the light pollution from sodium vapour street lamps is making itself known. This frame is centered roughly on the constellation of Cygnus, which nicely exposes the galactic plane.

Now, have a look at the photo above, another meteor? No, this one appeared in three consecutive shots - its a satellite! If you look very closely at the lower right, you'll see another traveling bottom right to top left of frame. This could be the tenuous link to amateur radio - which satellite is it? Is it an OSCAR? Maybe later I will check the photos metadata for the time, and see what satellites might have been visible

And this one, is that a satellite? It looks more like a meteor! But its neither! This also appeared in consecutive shots - its a tumbling spent rocket body! One thing I forgot to account for though was dew formation, so ive rather a lot of shots that are unusable because the lens fogged up!

So many people never look up more than a few feet over their own heads! And yet there is all this to see, if you just take the time.

So, in just a couple of hours skywatching we saw meteors, satellites, rocket bodies, stars and constellations, and a wonderful view back into the heart of our own galaxy. Add that to a good karate session, a beautiful sunset, and seeing a bloke riding a penny farthing - a great evening.

2nd Finningley Radio Rally this Sunday 16th

This coming sunday, is the 2nd Finningley ARC Radio Rally, held at their clubhouse close to Sandtoft Aerodrome. All being well, I should be there, to try and sell of a bit of surplus junk, and maybe get hold of a few new goodies myself. Bob M1BBV might be assisting me.

If your in the area, why not visit? Its a new rally, but geared towards the constructor, with plenty of components and junk to be had!

Of course, you may wonder what else there is to see? Well, Sandtoft is home to the Trollybus museum  http://www.sandtoft.org.uk/

16 August Finningley ARS Summer Rally *** New date - was 19 July ***The Hurst Radio Communications Centre Belton Road. Sandtoft Doncaster DN8 5SX.Easily accessible from the M180 Jct1/2.Open 10:00. Entry £3.00. Trade. Parking. B&B. Talkin S21. RSGB bookstall.Contact: Kevin, G3AAF 07831-614640.
www.finningleyradiorally.co.uk

Frog FAB!

Quite some time ago, I dismantled for parts a defunct 10W CML analogue UHF TV transposer. One of the things I kept from it were the thin anodized aluminium sheet covers on the individual modules.

Tonight, I decided on a bit of sheet metal fabrication! Ive measured and marked up one of these sheets, and using my mini-bender, formed it into a U-shaped box half, the first stage in making a cabinet for the Frog Sounds QRP transceiver I built a few weeks back

This sheet is only about 1/64 of an inch thick, and bends easily and accurately, although it is a bit flexible which makes filing the saw cut edges smooth a bit time consuming.

I'll find out some standoff posts to mount the PCB on, and then once I have the lengths of those, will mark and drill the holes for the connectors, controls and LED. The box will be a bit wide, but I really couldnt be bothered to do the necessary measuring, marking, cutting and filing needed to make a narrower box. Its as wide as the CML modules were!

I will also cut and fabricate another U-shaped half to be the lid. This I might have overlap the bottom section by a quarter of an inch or so. Ive yet to decide how to fix them together. I could use four long standoffs (or chains of standoffs) as pillars, or I could see if I am skilled enough to bend a pair of lugs inwards into which I can secure four M3 sized nut-serts.

Tape Measure Satellite Beam - UHF Build, Tested

A big problem I have when it comes to testing UHF antennas is that my analyzer only works up to 170MHz. This means that transmitting on UHF into a homebrew antenna is a bit risky! And its a risk I didnt wish to take with the tape measure antenna.

Luckily, I have a friendly engineer colleague, and he has an Anritsu Site Master test set. This machine will do what my spectrum analyser, antenna analyser, VSWR meters and more do, but from 25MHz to 4GHz! And today over my lunch break I put the UHF beam on it.

Despite the fact that I have inadvertently cut the driven element too short, because I forgot I had marked the whole inches but not yet the tenths, and then went and cut it, the Anritsu showed that the resonant point was only a little high, around 441MHz. The part of the 70cm band used for the FM satellite downlink (Mode J) is around 436MHz, and here the VSWR was still well below 1.5:1. Perfectly usable. And this reinforces the on-air reception test a couple of days ago where I could still copy French and Spanish stations working the SO-50 bird down almost to the horizon.

All thats left now is to decide on a mounting method to join the two beams together for use, and to try the combination live against a satellite pass.

Revox Revamp

As is probably known by regular readers of this blog, i'm a bit of a sucker for a nice bit of surplus! So when I spotted this beauty on its way to the WEEE man, I just had to save it!

This is a Revox B261 FM tuner. Its got to be the most perfectly retro set ive seen! It makes me think of a middle aged bloke, with this and its matching amp built into a teak cabinet, huge headphones on, a pair of cords, slippers, and pipe, puffing away to a good bit of prog rock...

It had a ticket on saying 'dead', but luckily, also naming the engineer who said so! So, a quick email to him and I knew its symptoms - doesnt come on, just makes a click as from a relay on power up. OK, so, something inside is working, even just for a moment! A relay is powering up! My suspicions, as always with a vintage piece, fell on its electrolytic capacitors, and in particular, the power supply.

But first, I had to un-mod it! The XLR's and the Eddystone box of DINs shown here are all part of the non-standard build inside, part of the use this set had been put to in its earlier life.

There were also several PCBs inside as part of the mods. All came out, and theres some very nice parts on them!

 All the mod parts are shown here. Theres relays, audio ICs, audio transformers etc. With these out, the tuner is back to its 'native' state. And I could start work

 The first thing I did, was to continuity check all the internal fuses. Oh look - F4 is open circuit! Could it be as simple as a blown fuse? Rated 800mA slow blow, I didnt have any but found some 1A which will do at this stage. I replaced it, and tried the power - still dead. Rechecking the fuse showed this one had blown as well. So, checking the circuit diagram, I now knew what I was up against. F4 protected the 9.6v windings of the power transformer, feeding the +5V regulator. The picture below shows the regulator card

 Notice the missing component? C1, a 2200uF 16v electrolytic smoothing capacitor, was dead short! Thats it in front of the PCB! With it removed, I fed the LM317 regulator IC with 10v from my variable PSU, and tested the cards output - A good 5V line!
After some digging about I found a replacement 2200uF 25v capacitor that fit nicely. Soldering this in, and adding a wire link to connect two point that previously did so via the three ground lugs of the original capacitor, meant that I could refit the card and try the radio. It failed first time, but only because I forgot to replace the fuse! With a new fuse, powering it up and pressing the buttons, I now have -

Yes! Its on!
 OK, so ive no speakers or antenna attached, so I dont yet know if it actually receives or if theres any output, but it powers on, the display works, the buttons work, the LEDs work! (alright so the display backlights dont work, but they are 36v filament bulbs - i'll replace them with LEDs)

I'll test the audio another day, but i'm quite confident its working. And for the sake of a few fuses and replacing this little bugger

I have a top of the range professional grade FM tuner! And its cost me nowt!

UPDATE - Ive just slipped out, put a croc clip lead on the antenna socket, and plugged in my cans -
It sounds amazing! This sounds to me how FM should sound! This is most definitely the best thing ive every pulled out of a skip!

What a muppet! - FT-857D CAT fuse

Feeling utterly terrible today, hardly able to think straight. So of course it was perfectly sensible to test to see if the FT-857D's CAT port 12v pin is switched or permanently on during my lunchbreak. It was of course perfectly sensible to do this by plugging in a bare plug, without its shell, to gain access to the pins...

Or not. As I discovered. Measuring the pin with the radio powered but off, showed no voltage. Measuring it with the radio on, showed 12v - for a moment.

And that moment was when the meter probe slipped and shorted the pin to the one next to it - GND! It even made a nice crackling noise until the internal, and ironically, surface mount, fuse blew!

Well, I suppose I have gained the information I wanted, the pin does appear to be a switched 12v line, so I can power the RT-11 from it. But, unless by some fluke I have a suitable SMD or micro sized fuse in my junkboxes, perhaps not for some time.

Crazy Idea? 144MHz Dismantlable/Transportable 4x Long Boom EME Array?

A strange thought occurred to me yesterday - with suitable thickness PVC tube, and 25mm/1inch dia. tape measures, plus various pipe fixings, it should be possible to build an ultra light weight, portable long boom 2m Yagi.

That being the case, it is clearly possible to build four of them, all identical. With that done, some more tube and they are on a H frame. A few more pieces and the H frame is mounted on an A frame...

Some cleaver bearings, a long guide handle, and some form of sighting system - and we have a portable EME antenna array!!!

Used with a 100W linear, a suitable masthead preamp, and a laptop running JT-65....


Just a thought

Tape Measure Satellite Beam - UHF Build, Pt 2

Building the UHF section of this antenna has proved somewhat trickier than the VHF section. For a start, the holes through the boom are a bit more critical, and although ordered my new reamer hadn't yet arrived to widen the holes a little at a time, so I had to do that carefully with a round file.

Once all the elements were in place, apart from the driven element and its support member, and all the sections aligned, the 'plugs' were secured with a liberal dousing in glue. Several coats of this glue might be needed to allow it to fully penetrate and make the joints fully rigid. The mostly assembled antenna was left supported on my workmate for several days for the glue to cure

Whilst the UHF section was curing, I got on with tuning the VHF. The driven element sections were trimmed to bring the resonant point close to the middle of the 2m band, and then a Hairpin match added to adjust the feedpoint impedance. Its actually resonant close to the middle of the band, but the match around the FM simplex calling frequency 145.500MHz (S20) is very good and the picture below shows just what it is around the satellite frequencies

Im quite happy with that! The Hairpin came out as about a 5 inch length of wire. The 50ohm RG-58 feeder is wound for 6 turns around the boom to form an ugly balun. Eventually, I might change the M3 bolts to some that are a bit shorter, as they are a bit too prominent and could catch on things during use.

Ive not yet tried the VHF beam on air. I'll test it at the weekend against several local repeaters.

The UHF section does now have its driven element in place, and is just awaiting connection of the feeder, and then testing and adjusting for the best match. I dont possess an analyser or SWR meter that works up to the required frequencies, so once complete I will take it to work and test it on the Anritsu Site Master testset in the service center.

Low cost Chinese components and modules

Its probably not gone un-noticed that I order quite a few components and modules from the Far East. One of the suppliers I use what has proved very good for low cost and/or bulk parts and modules, particularly for Arduino and Raspberry Pi related modules, is Banggood.

I have no connection with these guys other than I buy LEDs, Lasers, small modules etc from them. If these sorts of things are something you wish to buy (and if your following what im doing on here then theres a good chance you do) then if you follow the link below, and order from them, you become one of my referrals and I get a little bit of a discount!

So please, help me save money! - Banggood - electronics, toys, gadgets

Ive also noticed a large increase in traffic to  my blog recently, mostly form Europe and the US. I'd be interested to know what people think and what it is im doing that you find interesting. Feel free to leave a comment!

Mobile HF antennas and tuning

At present for mobile HF im using Hamstick type  single band antennas. The problem with these is they are rather big for a little car, and its quite a faf to change them to go to another band, especially if im just listening about, where I might be outside the amateur bands.

So, at the risk of reduced efficiency on lower bands, im considering installing my LDG RT-11 remote auto ATU alongside the FT-857D, which hopefully will give me some improved frequency agility, and particularly, allow me to use a shorter antenna for general utility listening.

The RT-11 is capable of fully automatic operation, retuning itself on any frequency change greater than 10kHz. But the manual states that the control line for this should be grounded momentarily on powering up, it doesnt say if it can be left grounded. It would be quite awkward to add yet another remote control cable between the radio installation and the control position at the drivers seat, so I need to find out if it will work as needed.

Unfortunately im not in a  position to test the theory for a few days!

I also need to haul out any junk I wish to take to sell at this years Finningly rally on the 16th!