Amateur radio station
"...papa golf one delta..."
I have joined the VRZA (Vereniging Radio Zend Amateurs), my administrative SWL-call is PA-11012.
I can receive signals form 160 kHz to about 900 MHz. It's fun hearing people communicate, especially from far away. Below one of my Yaesu HF radio's, a good starters radio if the front-end FET's are alright!
I restarted a license course radio amateur that I quit in 1980. Luckily CW (morse code) was no longer required, otherwise it would have taken years to go on air. Still CW appeals to me as the most pure form of radio-communication... These beeps will go, where everything else fails. It's mysterious and addictive, also very difficult to think K when hearing -.- or M being --, more so at speeds well over 12 words a minute.
For frequencies above 30 MHz I have an old Realistic PRO24 scanner and a second FRG-7700 with the FRV-7700 2m converter.
Amateur Radio station
On 09-11-2005 I passed the admittance-test and obtained the Novice-license, call PDØDF.
I have been very busy building my shack to go on the air on the U/VHF-bands... As a base station, I bought a Kenwood TS-770. It's an old dual band transceiver. After a long search I found a desktop mike to complete the set. It works very well, although there are reports of a slight humming in the background. Hate that hum, after lifting the top panel for a quick hum quest, I rapidly closed it again....;-)
After having grounded the set properly and switching off neon indicator bulbs in the power line, I did not hear any comments on the hum anymore ;-) Still not satisfied the seller was willing to check the set and found some faults he mended.
This transceiver is very easy to operate, all controls are placed very handy. The tuning knob runs almost the whole band when you give it a good spin.
Spring 2006 I received my full license. So I am admitted to operate on all amateur HF-bands as well. I am currently using:
Tentec Paragon, an American made all-band HF transceiver, 100W, original PSU and tuner. Yaesu FT847, all-band, all-mode.
HF Inverted V
<picture 1:1 balun>
Not much to write about. Two times 18 m wire cornered at about 110 degrees. It's simply a wire from a public tree in front of my house, to a pole on the roof, ending on the roof of my shed at the back. The impedance is about 50 Ohm at an angle of 110 degrees. The coaxial feed line is connected to a 1:1 balun. 16 Tri-filiair turns on a 40 mm OD PVC drainage pipe. Two bungee cords tighten the two wires on the top of the pole. The pole itself is a 30 mm PVC pipe, that flexes in windy conditions. But that !@#$%-pigeon doesn't mind that. Impossible to see the gray WD-1/tt wire running over the pole ...;-) This is original army field telephone wire. It has four strands of copper and three of stainless steel wire, strong enough to tow a jeep.
VHF 145 MHz J-pole
There are lots of building plans on the internet of this mysteriously famous design. A very simple aerial, cut from a FM-broadcasting dipole. It works just great. Also ripped another dipole to make a comparison 70 cm J-pole. Very good too.
Later on made a third one from 15 mm water piping. The feeding point is soldered on the base of the tuning stub. The core runs inside the stub and exits a few cm upwards to connect to the radiator.
VHF Elex/Elektor 145 MHz Yagi, 9 elements
I found a design of 2m 9 element Yagi beam in a magazine. First listening test were not so promising. During a TX-test with my transceiver, I could make QSO's with a horizontal polarized station almost 200 km away. I guess this antenna must be ok.
VHF 145 MHz Quad
After the troubles with the Yagi, I tried to a different design. This 4 element quad antenna has the advantage of easy changing the polarization. The beam is a 30 mm PVC tube that can rotate inside a 40 mm tube. This way I can adjust polarization (V, H or D). The 40 mm pipe is attached to the vertical pipe with standard PVC T-coupling. This is mounted to a directional rotator at the the chimney.
No clue what's wrong as this antenna does not have much gain. A project to pick up later again.
UHF 70 cm Ground Plane Antenna
The other day I needed a quick UHF antenna. With a chassis part HF-connector (PL-type, yes I know, it should have been an N-type) and some 4mm brass tubing I made this tiny antenna. The pipe fits exactly the soldering pin to make a driven element. This radiator is 182 mm long and the four radials are 186 mm. It works well. Some 3mm brass screws are used for tuning purposes (and to cover up measuring bloopers...).
This contraption was made in about one hour. In fact, fitting the PL-connector to the feed line took even more time...
My mother in law presents this antenna. She does not comply to any prejudices regarding mothers in law, as one clearly can see.
UHF 70 cm Yagi
The range of a 70 cm GPA is very limited, therefore I started building a 18 element 432Mhz Yagi. The boom is made from old aluminium garden pole, square 22mm. All elements are made from 8mm alu tubing, including a folded dipole. To get the dimensions right, I used DL6WU-software from Australia. The owner of the copyright is John Drew (VK5DJ), 34 Aitken Street, Millicent, South Australia 5280, e-mail email@example.com.
You can download this fine program from the web for free. It works very well and is kind of self-explaining. The author is even willing to give advice.
Even the 1/2 wave coax balun is calculated. This 70cm Yagi goes on top of the rotary mast, 70cm above the 145Mhz Yagi.
Only, I don't hear much on this band...
2 meter ZL-Special
Club member Evert PDØMVV owns a ZL-Special that he bought decades ago. It still works fine, but needed some maintenance.
After getting it on the ground I saw this Yagi was quite different than other ones. It had a double radiator and no reflector. The working principle is called "End-fire" and was popular before the contemporary Yagi's became common. The elements have a curious edge pattern.
I copied most dimensions and obtained Judd's, G2BCX, booklet "2-meter antenna book" in which this aerial is described in detail. And of course I built it ;-) Getting a proper VSWR is somewhat a hassle. It still is not satisfactory low as it should be.
Azimuth rotors are quite common and elevating rotors too, but axial rotors...? I have never seen these before. This project was to test to possibility to receive vertically polarized transmitters as good as horizontally polarized ones, e.g. distant repeaters.
A ham-ad delivered me an old Stolle TV-rotor for cheap. A complete overhaul was needed to be sure it would not fail. After hanging in the air for about 35 years it looked surprisingly good. Of course it has not been designed to be mounted at an angle, but we will see how long it will last.
As you can see above it is fitted in the middle of the boom of the ZL-Special. It works flawlessly. When tilted 90 degrees the strength of vertically polarized stations increases with two S-points. It should be much more, but the VSWR of the ZL-special is bad.
Comet 2&70 dual band antenna
This could have been my first off-shelf antenna, but it was not... My brother discarded this antenna after a decade of service. It missed a stainless radial, but for the rest was in near perfect condition. A squirt of WD40 and some machining to fix the radial was needed to get it working a gain. Great antenna.
This bird of prey keeps my antennas clean. It does not drop anything itself ;-) Handcrafted from acrylic glass, airplane-modelers paint and a picture by Google.
From this website http://www.oe5.oevsv.at/basteln_js/technik/afu_betrieb/antennen/logperiodic/logperiodic2_70.htm I got info to built a dual band logarithmically periodic array LPDA. Why? Because I had no clue on how these LP-arrays work.
This aerial is broad band and runs from 140 to 450MHz with almost an even VSWR. It is about 1m long and still has a gain between 8 and 10dB.
Data from the website is enough to get started and finish a good antenna. Materials needed are easily to find in a home depot. Some trouble with the German language made me decide to skip "Abstaende" and concentrate on the absolute boom positions. In particular, as I applied 6mm rods and a 20mm boom instead 4mm rods and 15mm boom. Boom distance is 10mm giving a VSWR of 1:1.3.
This aerial looks like a Yagi of which the front half is folded backwards. The double boom makes it look bombproof indeed. It is mounted entirely in front of the mast, the feed line dropping from the longer boom at the rear.
145 MHz Elektor converter
Finished but on halt, looking for why it will not work...;-)
145 MHz Elektor receiver
On halt, looking for difficult to get parts.
When I was young, never built "the stupid thing". Being older I could not resist this simple idea of the detector radio. Having split some telephone wire, I finally ended up with a rather chauvinist coil, but it works and it receives even... foreign stations. Radio 10 Gold very loud in the earplug, even during the day. Used a Siemens AC151 transistor from Frans Bakelaar's shop in Den Helder.
Very interesting and similar basic radio topics can be found here here.
Active Magnetic Loop
As the idea of Wellbrooks ALA seemed appealing to me, I wanted to try a clone amplified loop antenna. Second attempt to built such an active antenna. This time the Elektor-design 2/1995 was used for the electronic part. You can dial down the pdf from Elektor's site for 1euro30. A bit difficult to get the obsolete G2/3FT16 ferrite ring cores, received instead the smaller Amidon FT50-43.
I soldered from 22mm copper pipe a 1m diameter octagon. The pcb is bolted on the two flattened ends of the octagon.
The reception is poor, not as good as a simple dipole. There is a weird distortion of the signal, as if a station is received twice with a very small delay. The circuit simply quits above 3.6mc, where it should start to amplify more. Some original ferrites are on there way.
Apparently another very difficult to reproduce Elektor designs. If the new cores don't do the trick, this was my last attempt building any Elektor design again.
Klaas Robers, PAØKLS, designed a 80m reactive receiver and published it in Electron, 1995. It is to be built on a piece of plywood with brass nails. Always was curious to hear this type of receiver, nicknamed "The Mexican dog" or "The Whistler". The location of the parts is almost identical to the diagram, in about the same way as the Philips Pionier was built.
Nail board almost ready. When you are used to solder pcb's , this floating parts method is not as easy as it may look. But it's fun...
This software program looks great, could even I learn CW with it?
ON4MAC MacKey, Marconi-style morse key
This key was made of solid brass with a redwood base. Only a few parts are steel, wood or plastic. I saw some nice pictures on the internet and decided to ask the designer some advice to construct it myself.
After having contacted the designer Michel, ON4MAC, I started building this beautiful Morse key. It was fun making the parts, having all the tools at hand. When you don't own a basic machine shop, you should not start such a project. Some parts have to milled, drilled and tapped.
It works very well and after all, it was not as difficult as I thought it would be.
The assistance by Michel was a great comfort, since he fabricated several of these keys himself. Some dimensions are critical. The ratio between knob, pivot point and both contacts is carefully determined by examining several other keys. They must be maintained as exact as possible.
Thanks very much, Michel!
Albert, PA3GWC, did some live testing and found the key ok. He made some QSO's with it. Thanks Albert.
Via E-bay I received this Morse key. It was in good condition, but needed adjustment and maintenance. I only had to re-spray the cover olive drab, army green, RAL6014. It is a beautifully engineered instrument, with very precise contacts. They say this the best key to learn Morse.
After a thorough inspection and comparison to the original manual, I discovered the rear adjustment system had been tempered with. Both indicator rod and stop rod are missing, ball and spring have also gone. The tiny contact wire however is still there.
The adjustment of the pivot points is easy. One side has a single screw, the other side a screw and an adjustment nut. When removing the arm this can be done without disturbing the adjustment, simply by removing the single screw.
The tiny pcb holds an IC that knows all about morse code. It is used to connect a paddle key to the rig. Found it in a newsgroup ad as obsolete. I fear now I must also try to find or make a paddle key.
"Just Learn Morse Code" by Sigurd, LB3KB
A great program, very much like the one mentioned above from G4FON. Nice addition is the possibility to enter characters and, in doing so, measure your score. When over 90% is ok, you can add a new character to practice. This works great and makes learning a bit more effective...
Trio-Kenwood Ham clock replica
A local OM had this old clock in possession, but it had failed after long service. It appeared to have a broken motor. The clock is an ordinary spring driven one, but the winding is done automatically by a 1.5V e-motor once every ten minutes. I dismantled it completely. One of the tiny brushes was worn. From 0,1 mm spring wire I bent a new tiny fork, matching the existing brush. It worked!! At least for a while ;-)
As this clock looked very interesting for amateur radio use showing time all over the world, I made a drawing and scanned the scale. In short, I cloned it and now have the same clock... The mechanism, however, is a modern 24 hour scale Quarz type, "World clock dial".
VRZA / HAJE's HF Antenna Analizer
On OM Luc Pistorius' site there is a nice design of measuring tool for HF antenna's. It can determine the impedance and resonance. The good part of the kit is that the alignment is very easy. It looked a difficult job to get all the HF-parts together, but luckily the VRZA and a company called HAJE-electronics are already selling a kit.
I built it and first results show it works well. De digital display shows clearly the resonance frequency's where the meter dips. No longer doing difficult arrhythmic and tricks in the air, just carry the AntAn to the feed point and read what is actually hanging there...
After contacting Michel again I started building a copy of the paddle he designed. It is a repulsion paddle, so there are no springs, only tiny magnets. Don't think this will make constructing it easier..!
Although Michel's design is square, I made it round, from round brass stock 100mm by 20mm thick. It was not possible to get a brass square 100x100x20mm for a reasonable price. www.Locloods.nl delivered the round chunk for a very moderate price.
Because of its round base I renamed my copy MacPuck.
It has become a very nice and stabile instrument. Thanks very much again, Michel!!
To transfer and decode digital and Morse signals from transceiver to the pc and back again, there is a danger of introducing ground loop hum and short circuit gates of both devices. The solution is to separate them both electrically by transformers and opto-couplers, aka galvanic separation. A PSK-box prevents these dangers and the building of it is not difficult. All parts were found in a discarded cordless phone...
On the website of the FRAG you will find all you have to know to built this box yourself. The sticker was printed on self-adhesive sheet with a desk-jet printer
On my pc's soundcard the level of Line-out was too high for the transceiver. I simply enlarged the variable resistor to 100 kOhm. Also some transceivers will not switch PTT with the opto-coupler. I added a BC547 to make a Darlington that can draw 50mA, enough to switch any transceiver PTT. Some extra LED's were added to monitor the signals.
Warning: don't short circuit the input wires, nor solder to pins while testing... If you do, you can blow up a chip on the motherboard. I also did this and it will cost an additional com-port adapter card to get serial ports back again. Mind you, these IO-cards are no longer as cheap as they were in the old days.
Works great for digital modes. The jumper settings can be somewhat difficult, when your set is not mentioned in the manual
Good VSWR gauges are very expensive, therefore I tried to built some of my own... The first one, Molema's strip line design, seemed to be ok, but did not give the same readings as a factory type VSWR. Somehow it seems to dip on a different frequency.
A second attempt was also a strip line design (DF3OJ) with LED's instead of an ordinary dial. The same strip line design, with slightly different dimensions and adjustable terminating resistors. Somehow the readings are erratic, probably of spurious radiation on the voltage lines.
I studied the design of a Monimatch in Rothammels Antennenbuch and prepared a piece of AircomPlus. This cable admits penetrating pick-up leads on the inner isolation as there are small channels of air in it. Still experimenting on all three projects
Lacking patience more and more, I ordered a Diamond SX-1000 VSWR gauge to have at least reliable source to make comparisons with home-fumbled VSWR meters. You can't build it all...
Restoration of a Tonna F9FT 2m cross-Yagi
This Yagi was in relative very good condition when I got it. It has been used near the coast. Salty water vapors did not have any negative effect due to the application of spray wax.
After getting an owner's manual, I discovered some parts were missing, amongst which two sleeve-"baluns". Consulting Rothammel's Antenna Bible and the Tonna booklet, I made my own sleeves for this antenna. Surprisingly the Tonna sleeves did not seem to comply with the sleeve theory. The grounding point of the sleeves, the fixture to the boom, was not connected to the braid of the coax...
The bazooka-pipes are flanged and fixed inside the N-connectors at the ground side, the fixture to the boom. This way the braid of the coax is also grounded at the fixture point. On the other end, the pipes are open, isolated. RG213 is run through these bazookas. The goal is to prevent a radiating braid of the coax. Rothammel translated Lindenblad's patent, 1936, to "Viertelwellensperrtopf".
Furthermore missing was the fixture to the mast. I made a new one, but this was not a permanent solution. The boom bent far too much in one plane. Still working on a better clamp for a stabile X-setup.
Restoration of a WiMo/ZX-Yagi 2000-Minibeam
When inspecting this antenna I found there was a high DC-resistance between most of the coils and tubes. At some elements it was even infinite. This could not be right, so I completely dismantled it, made some drawings and built it together again with new coil wires and better connections (I hope).
<table of coil windings>
It appeared the aluminium 1mm coil wire had become brittle and the connections to the tubes at several points had even broken! I reckon the almost permanent flexing in the wind of the elements causes a slight movement on the wire connections which will deteriorate and eventually break. I exchanged the brittle alu wire by much tougher 1mm LUX Stainless binding wire (Homedepot, gardenshop). One expansion plug, that connects the coil wiring to the terminal, had to be replaced. It is a simple M5 brass stone wall type plug.
On last remark: the manual says to lower the SWR by connecting one half of the antenna to ground by a strong short lead. In my case I had to remove this wire to get a good SWR-figure ;-)
Although this antenna is named Minibeam, it still is huge...
New antenna mast
On top of my house there is an accessible flat roof on which I planned to build a small mast, not exceeding the maximum allowed height of 5m above highest point. At a Scout's center they sold this nice steel mast for a reasonable price.
There was only some minor rust and after a re-paint with Corroless-primer and ordinary glossy paint it looked satisfactory. Got it 8m up from the inside all by myself, inch by inch ;-)
The current configuration consists of a Yaesu G-1000 rotator, Diamond V-2000, 2m Elex Yagi, WiMo/ZX-Yagi 2000-Minibeam and a 80m Inverted-V wire dipole.
I have made plans to make the mast lighting-proof by a professional.
Hygain FM208 VHF Yagi
This antenna was given to me when I bought a FT847 from a OM who quitted the hobby. It was packed in a never opened box and wrapped in American 1986 newspapers!! So it is brand new. I will try this aerial for the Friese Elfstedenronde when I have discovered which side to put upwards. The booklet does not show this.
Artificial ground tuner
At this time I am busy building parts for a Ground Tuner. As my shack is on the second floor, it is rather far from the grounding-pin. This could lead to a greater resistance of the ground-wire on certain frequencies.
The object of a ground tuner is to let the wire resonate at a given frequency and therefore reducing it's resistance. A switch able coil in series with a variable air capacitor, is used to tune the grounding current to a maximum, i.c. reducing the resistance at that frequency to a minimum. Great idea!
On this site
I found a nice project to build a suitable capacitator. I discovered there are lots of other worthwhile projects here too. Very well documented!
First step was making the coil. Next came the CNC-milling of the rotor-, stator- and fixture plates. Then turning 49 4mm 8x6mm distance rings. The trick with two bits works great, all rings are exactly of the same length. Do not forget to measure the inner diameter of the 8x6mm alu pipe! Mine did not fit a 6mm Silver steel rod. Use a reamer before parting a ring: it's very difficult to ream these tiny rings by hand ;-)
<picture finished capacitor>
Triple synchronous UTC-Wintertime-Summertime Clock
In addition to the Kenwood-Trio replica clock I wanted to have a clock that continuously shows UTC and both possible local times, i.c. wintertime and summertime. When visiting a new shop in town, Steengoed, I found very cheap quartz movements for only 1 euro each.
The object was to let the three clocks tick all at once. In other words, to let the clocks run to the second precisely. The only possibility to do this I could think of, was to use one - master - quartz driver an two slave clocks. Of course I could have bought three expensive atom-time slave movements, but I did not see any challenge in that option. Even more so as these clocks run very accurate by themselves. This is how it finally looks like:
ZULU (utc) ALPHA (winter) BRAVO (summer)
Mnemonics: ZAB123, Spring Forward Fall Back
After carefully dismantling the movements I learnt how these devices actually work. A very small pcb delivers two 2 second pulses to a single coil, one pulse to each terminal. This pulse, only 0.3V, generates an alternating current each second in the coil. A small stepping motor rotates at this at every pulse. This rotation is passed to the gearing of the clock.
On the back you see the wiring, simply daisy-chaining each movement. Try to figure out yourself how the wiring actually was done ;-) Don't be confused when the third movement is not running; just switch a second battery parallel.
EH Antenna experiment
As often new idea's always draw a critical eye, not in the least with this antenna. The theoretical explanation to be found on the internet exceeds also my mathematical skills by miles... This is why I shall from now on wrongly refer to it as the ()nhanced ()ertz antenna. Just to make sure nobody ever wants to ask me how it works ;-) Critics say it's a hoax, it is not possible to pump enough HF-energy in such a small aerial. The feed line will radiate even more than the actual device itself. To be honest, I also have doubts this design will ever work as well as a full sized wire dipole. However, these days EH antennas have become a commercial product. Even more reason to go for a test.
Meanwhile I made two EH's, one for 20m (left) and one for 40m. All data is easily obtainable form the internet. Material can be found in trashcan, dump yards, etcetera. I used an old left over piece of alu chimney pipe, some household wiring 2.5mm2, some PVC pipes and a piece of stainless flashing.
The 20m EH is an ordinary 500x50mm type, with an axial adjustable source coil. The second coil, the tuning coil, has one lead running in the center of the PVC pipe, connecting the upper cylinder.
The much larger 110mm 40m EH is a so called "star"-type. It incorporates an extra phasing coil between the two cylinders. It needs some puzzling to get all parts together and in the same time guide and connect the internal wiring properly. I centered the upper cylinder connecting wire through the middle of the pipe by means of several polystyrene disks.
I will report progress on this page.
80/40m trapped dipole
My last experiment is to add 40m traps to the 80m inverted V. With help of a trap calculator from VE6YP, Tony Field, firstname.lastname@example.org found on the web, I made two traps. I did some dipper peasurements but missed the resonance frequency by miles... Still working, always fumblings at hand.
Cloning a 10-15-20m minibeam
The storm of 18-1-2007 ripped my tower apart, in fact it must have been the last gust at 22:30h that did it... This was caused by a too small overlap of a steel wire in the clamp, actually only one clamp failed...! I overlapped the U-clamps by about five times D of the wires, it should have been ten times D, I reckon. But what a miracle, only the upper rotating pipe and some parts the minibeam were damaged. The rest seemed ok. With the help of some assurance money - they never compensate full damage - I started repairing.
When the minibeam was taken apart completely, I saw it was possible to repair it and also clone the entire minibeam. Lesson learned from previous projects like this, I started to clone the most difficult parts, the center extension coils and the element trap coils. I ebayed some Delrin (pom) from Germany and did a trial on both a center coil and a set of trap coils. This is how it looks like:
As you can see the bobbins are pre-cut with a threading. This is probably done to make mass production easier and maintain coil dimensions properly. I measured a pitch on the center coil of 2mm, the trap coil threading pitch is 1,5mm. The 4mm groove on the center coil body is meant to route the connecting wire to the second coil. It will only take an extra set of two trap coils to complete the director.
The completed center coil will slide into a 450x32mm pvc-pipe. Each trap coil section will fit in a 300x30mm aluminium tube, sold as cloth hanger bar. (Praxis, Home Depot, local hardware store).
Original aluminium trap coils and cloned copper ones. The wire is pinched between two stainless disks by a inox screw.
Elektor SDR USB receiver module
This spring I started experimenting with Software Defined Radio and Digital Radio Mondiale. I have been waiting some time for a kit or whatever payable item to play with. Elektor launched recently a nice module that is sold ready-made and tested. No way I am soldering these SMD's myself anymore ;-) The complete receiver module is not bigger than a QSL-card.
I am using the free G8JCF and I2PHD software to receive HAM-bands. And Dream.exe to also decode RDM signals. With only a few meters of antenna wire there is already considerable reception possible. PSK and CW are heard very clear. Phone is a bit more difficult to tune. Reception of DRM has been so far impossible.
Update 10-01-2010: Adding a RF-Systems MLB makes a huge difference..! It is now possible to decode DRM for a longer time. CD-stereo on SW..! As the experiment is progressing slowly, I have ordered the Elektor SDR preselector. This board has been designed to match and upgrade the SDR module.
Meanwhile I have started using DRMdisco, made by Claus Knütter. This - also - free applet lets you find and select DRM stations much more easily.
Yaesu FRG-7700 SDR modification
With a Sat-Schneider DRM oscillator kit I am currently modifying this nice radio. It is not a destructive procedure at all and can be reversed at any time. The tiny oscillator board is soldered to a ground testing pin and is hardly noticeable. Four wires to accommodate power, 455kHz in and 12kHz out. Test results soon available here. Preliminary tests have shown the FRG frontend is as deaf as a post..!
According to Eham-reviews the CobWebb® antenna should be a great asset for the shack against minimal costs. This original "CobWebb" design of Stephen Webb, G3TPW, can be bought as a kit for about 250 Pound. It's always a challenge to make a good copy for less ;-) However, in retrospect I must admit to have spent more money on it than planned. So a Cobweb it will be, not a CobWebb®.
Basic material needed to built this five-band sturdy lightweight:
5 Telescopic 4m fishing rods, 5 euro each, 50m of 0,75m2 speaker cable, , welded center brace, 27mm steel hvac-pipe.
From four poles only the two thicker parts are used for the arms. One pole's end part is needed to support the junction box.
I have tried to minimize the amount of steel inside the dipoles' plane. It seemed to me any metal parts inside the bended dipoles can a source for trouble. A workable solution was to compile a five-armed brace from short pieces of tube that can hold the rods. As the rods are slightly conical, slits are made to squeeze them to a tight fit. Stainless 35mm hose clamps will do fine. With two 60mm hose clamps the vertical steel angle is attached to the mast. Hopefully strong enough when these "170m/h gusts" come around...
G0MTD's instructive pdf was of great help to understand the working and construction of this antenna. Test results will be added later as usual, if ever.
First thing is to do some measurements with analyzer and probably some cutting to get the SWR right on al five bands.
Fall 2008 I made some QSO's to see what this aerial did with the newly acquired and restored FT7. The SWR-reading was still bad, but nevertheless an Italian OM near Rome heard my 10 Watt call. He cranked down his Icom and we maintained contact with only 1,5 Watt.
Update 10-01-2010: During the winter of 2009-2010 the SWR on all bands went bad. Somehow water had crept into the feed point. The body of the pvc box was pulverized and gone. Strangely the lid was ok. Also there was some dirt and corrosion in the screw blocks, so I decided to replace these with another system. All dipole halves were twisted together and soldered into a single screw block on each side. Now the feedline can be connected to only two blocks and only two screws.
The rest of the hardware looked rather well, after a few years in the sky. Still the SWR was not as good as it was before, so I made a new set of dipoles, using some modified figures found on the web. On the shortening points I did not twist and solder the leads, but used 3M squeezable capped cable connectors. The ones used in cars to split wires or make T-junctions. Might a certain point be off a few centimeters, it can be easily corrected.
Talking postcard call generator / voice keyer / DVR
While cleaning up the attic I discovered a long forgotten recordable Cola-postcard. Even the batteries were still ok. Immediately I saw an opportunity to fumble myself a really cheap voiced call generator. "CQ...CQ...CQ...PapaGolfOneDelta...QSL", repeated a thousand times can become such a bore. A fine addition to my PIC-Morse-generator.
This is how the intestines of the card look like.
Clockwise starting at twelve you see the play button, speaker, EndofFile-pulse/10sec. recording LED, record button, 6V battery pack, power switch.
Goal is to hook the contraption up to the set by means of a audio transformer and a PTT relay. Pretty much the same as described in QST, April 1995 (thanks again, André PE1HWO). The idea is to press the play button which start the voice file and flip the PTT relay. When the End of File-led pulses the relay should fall off.
Update: Okay, after a lot of sketching and searching the drawers, two 7400 NAND's to form a latch (flipflop). One input is the down pulse of the play switch, the other is taken form EoF-led as a reset. Both using differentiating C's. The PTT-relay is now clicking fine in sync with the recorded message. The audio goes to a separating transformer and a 1kOhm voltage divider to hook up via a 1uF capacitor to the audio input.
Restoring a Yaesu FT7
The other day I was given a big box HAM-stuff for free, amongst which a very nice FT7. Sadly as dead as a doornail though. May be I'll make a seperate page about the restoration as it involved quite some work. Like remaking baseboard connectors and replacing some transistors. Now it is working properly again and I must admit the audio is so much warmer than modern DSP-sets. Many thanks to the FT7 Yahoo-group.
(to be continued)