Wakefield Rally

Went to Wakefield radio rally today. Got there just after opening time. Very few dealers this year, but was pleased to see two very good vintage parts stalls, plus a stall by wakefield ARS. Sadly, this was a silent key sale, but it seems the chap was a hoarder. First i grabbed a VHF/UHF Manual for i think it was £3. I then started rummaging. Eventually coming away with four big tubs or old parts, in one of which was a bag of NE602s, which are worth what i paid for the rest! I seem now to have aquired literally hundreds of vintage transistors!

Got a few parts i actually went for, inluding a nice 600pF variable for £3, some 250pF postage stamp trimmers and open frame jack sockets for the ZN414 matchbox radios, and a big stock of brand new ferrite rods.

Some of the ICs amongst the junk i got are of no use to me but still in packaging - there now on ebay. If only a few sell, i will have recouped the days spending!

I missed out on a spares or repair HF magmount with various loading coils, simply because i didnt think it would be cheap. The next chap to me asked the price, and when told 'a fiver' his eyes nearly fell out, his jaw fell off, and he couldnt get his wallet out quick enough! Its a shame, as that would have gone nice with my new toy...

Also, Sam asked me to bring him 'something interesting', well, for 20p I found a wooden bayonet mains plug!

Oh, and mentioning my new toy, thats something else i was looking for, an auto ATU to go with my new to me Yaesu FT-857!

Let there be lower wattage light

After some fun and games fathoming out how the kitchen lights had been wired, I now have four 4w cool white LED lamps working, fed from one 26w driver transformer.

It turns out that the supply mains went to one of the lamps, and from there broke off as two spurs, each spur feeding two more lamps as a daisy chain. It soon became aparent that i could reuse the wiring.

I had hoped to pull the feed to the lamp over the door (the one without a LED lamp yet) and keep that one as halogen for the time being, but it proved impossible to pull the cable, likewise there was no way to feed a temporary mains supply. So, that one is also wired for LED, and is awaiting a lamp.

A check of the energy monitor, showed that the lamps are taking the expected 16w. This will be 20w with the fith bulb installed. Thats quite a saving from the 250w the halogens took. With all the halogens converted to LED throughout the house, the consumption will go down from 550w to a meer 44w. And the MTF (mean time to failure) for the LEDs is quoted as 50,000h, against the 5,000h for the halogens. At £8.50 a throw, theyre not cheap, but at about £1.30 each, and needing ten to last the same lifetime, the halogens come out at £13! Assuming the lamps last as quoted, thats about £50 saving in lamps alone, and roughly £60 a year in electricity. It also means that if they all last their lifetime, i shouldnt need to change them for about 27 years!

Early Adopter

Being an early adopter of any technology is not something i would normally do. I like things to have been well tried and tested, and brought down in price, before i use them. I dont have a Blueray player! I dont have a HD TV. I certainly dont, and never will, have a D-STAR radio!

But, there is one technology that i'm happy to try out - LED. I have four 4w LED downlighters and a suitable transformer, ready to try out in the kitchen. The prospective savings over the halogen 50w units, over the lifetime of the lamps, is staggering.

But of course, the builder was never going to make anything in this house easy! And this is certainly the case with the kitchen lights. There is NO access panel into the ceiling void, and no access from above. So everthing has to be arranged and wired via just the five 5cm holes in the ceiling! The LEDs need to go in parallel, fed in a loop from the transformer. The halogens that are in each have their own transformer, and a mains spur!

I expect each of the five lamps to look like this. Hopefully they will all have a mains junction box, which will allow me to safely disconnect the feeds. Routing the new DC ELV cable through the void might prove to be fun!

Theremin and CW

Yesterday, I decided enough was enough, and that the power supply for Daz's theremin just had to be completed. So, with a mug of tea, and the fan heater running flat out, i ventured into the garage and cracked on. A bit of customising was required on the case, but the power supply is now finished. +/- 12v dual rail, independently fused, to a standard 5pin 180deg DIN plug. I can now, when i have the time, start working on the main Theremin circuit again.

I also built an incredibly simple circuit - a meter tester. This is nothing more than a 1M linear pot and a AA battery, housed in an old shaving stick. Yet, oddly, it doesnt seem to work properly! Everything seems to measure ok, but when on a meter, its all or nothing. Odd.

Since ive decided to make the concerted effort to master morse, I though as well that getting the practice oscillator running properly was in order. Up until now, the headphone output had a strange 'drop-off' tail on key up. The output transistor, a BFY51, was feeding the speaker via a 100uF electrolytic and a 100 ohm emitter load as a common emitter circuit. I suspect the cap was responsible for the problem with phones at low levels. I tested it today with the load resistor replaced by an audio transformer, and the speaker and phone socket on the secondary, and it seems to work just fine. Only problem, it no longer fits the box its in. So rebuilding it will have to await the Wakefield rally in a couple of weeks to aquire a suitable box.

The next little project is just that, little! I have a stash of ZN414 equivalents, and Sam has shown an interest in a matchbox receiver. Its a long time since i built a little AM receiver, so i think we'll have a go at this. Just need the matchbox!

Bent-Runner

Well, the weather has been dire today, far too cold and damp to put either mast up, or to run the coax. So, it has been indoor tasks only.

The VHF vertical doesnt fit on the top of the Clansman mast. I need a spare mast section to cut down to form an adaptor to allow mounting of antennas like this, but short of buying a whole spare mast, it might be hard to come by. Ive put the feelers out.

As for the telescopic mast, the big task was meant to be fathoming out suitable guying. I think a stay point at the 4m and 7m levels is needed, the bottom can still be held by the 1m level bungees, and the antenna wires will attach at the 8m level. Except for verticals, the top two sections are too thin to be of use. Ive a couple of sheets of PVC gluing together to make a thick rigid sheet from which to fabricate guying rings. As the mast tapers, each ring will be unique to its level, and so they will only fit in a set order. The other problem is tensioning the guys. The Dacron line i have, whilst incredibly strong, is very thin, some 2mm if that. £3 in Yeomans, i found a pack of ten 'bent-runners', ie guy line tensioners for tents. These have got big holes in them so i didnt think they would work, but the homemade one i fabricated earlier today the holes were too small, and passing the line through would be awkward. A quick trial with one of these and a length of the Dacron however and the seem to hold fast. I might have cracked that problem!

I have played some radio today, tried for HK0NA but the level of idiocy and QRM was astounding! Did work a SOS radio week station in Torquay though.

Antenna Work & VP8s

Up the side of the house today, removing the remains of the wind shattered 2m slim jim, and salvaging its coax. Luckily, the rain hasnt got into the coax, so that can be rerouted up the rear of the house and into the loft, where i can then use it as a test bed for smaller, short term antennas, with a dipole orientation N-S (so a chance to work the African continent on the higher HF bands!)

Anyone who knows me will know i have no fear of hights, but i hate ladders!

Ive already made an 80m inverted V for use with the 10m mast, plus a 10m J-pole. However, with the new year started and the offer of the SES for the Doncaster Show in september, somewhat more radical, practical and portable antennas are now needed! Apart from 2m FM (the mainstay of town SES'es) such a 2 day event calls for HF, and a selection of bands to cover eventuallities. Ideally of course, i'd be able to use any band, but that would call for a compromise of the G5RV type, and two masts, at least. This may be possible using mine AND G7PZLs 5.4m clansman masts, but it wouldnt be very high. So, a fan dipole/maypole design based on the 10m telescopic mast is needed. The question is - which bands?

In the past, ive found 80m to be a prerequestite for SES. So which others? 40 and 20? What about 15, 12, and 10m? Topband is out on the practicallity side, and 30m isnt needed as this will be a phone op.

Im going to test a few ideas out tomorrow based on the clansman 5.4m mast, at the very least to verify that it will take the 2m vertical without any issues!


On the operating side recently, not much! However, yesterday i was very pleased with my little tune around on 17m whilst taking a break from gardening. Heard VP8LP Bob, calling CQ, no replies, so thinks i, grab him if i can before the EU zoo arrives! So, i called him, little realising i was set to 10w. Anyway, to my immense amazement, he replies! I quickly hit the button to go to 100w, as 10 just wasnt going to be reliable, and instead hit the AM/FM button. A good few seconds later i was back in control, and Bobs phone is ringing! I QRX, he returns and we have a pleasent natter for a few minutes. I give my 73 as i need to crack on with the veg plots, but Bob asks if i'd like to work another VP8 before i go? (Having been after the Falklands ever since i got HF, then its a moot question!), turns out Zorro VP8DNT is visiting Bob, they quickly change over, and ive got two VP8s logged in 10mins!

80m Field Vertical

Im going to get cracking with this. I have a 10m fibreglass telescopic pole (a windjammer), for which i have already worked out a neat guying system using bungy cords, and have created a radial plate for it.

The proposed design is a top-center loaded vertical. The coil will be positioned 8 ft from the top, allowing that bit extra wire for capacity. Calculations show this should be about 55% efficient. Combined with my MKARS-80 giving 3-5w, this should let me have an erp of about 2w. Not great, but the real benefit is expedience - i can get this rigged at a portable site/summit in about 5mins

Im also considering a linear loaded coil vertical. But winding the coil every time i put the pole up would be slow, tedious and inaccurate. I wonder what a slinky streched over 30ft will resonate at???

QRV 6m

Well, ive not updated this for, ooh, i dunno, ages. Other things have taken the time.

Anyway. I now have the doublet back up, and its working ok. Its not perfect, but its working sufficient to make contacts, including some nicely impressive DX. Yesterday, on 17m, i worked Cuba with just 10w, for example.

The 3 element yagi for 6m is up, albeit on the 'test' mast, at about 15ft. 6m is very good at the moment, plenty of sporadic E to work.

The one thing that has struck me about working SSB on 6m, is the business-like operating. No messing about, reports and locators, and then clear, but at the same time not overly rushed. Very pleasurable short QSO's.

Im still considering the best way of securing the main mast to the side of the house, im not at all happy with expansion bolts into engineering brick, i just dont think they will hold well enough if they penetrate one of the voids. Im wondering about using a steel backplate and M10 threaded rod right through the wall for the top bracket, which will take the worst of the wind loading. The pole i have is steel, so its heavy. Maybe i should bite the bullet and get an aluminium pole ordered!

Julie is not particularly keen on the 6m yagi, so would be even less happy with the 9 element 2m Tonna. But if they were up at 30ft, perspective means they look smaller. They will also perform better!

Getting it up

The sealant cured on the slim jim, and its now mounted in its tube at about 15-20ft. Oddly, the SWR has gone up, and its now between 1.3 and 1.5:1 across the band, the lower figure towards the high end. Ive not had chance yet to do an on-air check, but receiving using the FT-290 plenty of repeaters and a fair bit of simplex is about. Interference from the ADSL modem was still bad, but some serious coil winding has removed most of it. I found the majority was coming from the network connection.

The HF doublet is shocking. Im blaming the change to a 1:1 coaxial choke balun, from the 4:1 collins. But the state of the feeder is also a worry, its been patched up several times and im sure there is still corroded sections. I have a 100ft roll of shiney new 450 ohm ladder line awaitin gthe rebuild. Probably i will go for a 135ft version, fed right back to the shack with 450 ohm. Im going to invest in a bottle of liquid tape for weather sealing the connections, and will also wind and solder the connections from the feeder to the antenna elements. Any splices in the feeder will be done to ensure continuity of impedence, and the feeder will be stood off from the fence etc along its path using electric fence insulators. I can then experiment back at the shack entry point with baluns etc.

I also took delivery of a 100m drum of 1.5mm2 conduit wire today, bought especially for antenna building, in particular for trying a 'stealth' 17m vertical mounted in the tree, with four tuned radials.

VHF Omni

fed up of having no antenna for 2m, other than an indoor whip, and with the prospect of getting the beam up still a way off, i set about coming up with a cheap and dirty 2m omni. My plan was to build a coaxial collinear, but having taken stock of what materials i had laying about, decided that for simplicity i would build a ladder line slim jim.

Initially, i designed my own, taking account of the velocity factor of the line. This worked, but i couldnt get the SWR down below 1.5:1. The matching section was made from 1mm mains wire stripped, as 300 ohm ladder line is a begger to strip neatly.

However, a review of the designs had me adding a few centimeters more line, in accordance with other designs on the 'net. This new version comes down to 1.2:1 at 145.500MHz, rising only a little at the band edges. All this is at ground level and indoors. An outside test at 15ft with the original showed the SWR to come down.

Now, its pretty much useless as is, built on a length of wood. So a trip to the wholesalers brought in some 20mm PVC white conduit. The whole assembly fits neatly into a 2m length, with plenty of spare tube near the bottom for mounting the antenna. I did a 1min microwave absorption test on a sample of the tube, and it was barely warm, no more than would be expected from being near a cup of hot water. A few holes drilled allowed cable ties to secure the antenna inside the tube, and some sealent in either end waterproofs it. The seal is domed carefully by smoothing with wet fingers at the top, whereas the bottom seal around the coax was done by shoving the mastic nozzle right in and giving it a damn good squirt. Some self amalgamating tape finishes it off by sealing the cable tie holes. Its attached to my test 100ft RG-58 cable at present, eventually this will be severed at about 5ft and a BNC added.

All that remains, once the sealant has cured is to mount the antenna and test it on air.