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IW5EDI Simone – Ham-Radio

EH Antenna for 80 M

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This is a picture of my EH ‘STAR’ antenna for 80 meters.   It has two cylinders made from aluminium flashing 30 1/2” long, wrapped around 2” (2.375”) PVC pipe.  Below the cylinders are two coils for matching and developing the EH field.  There is a phasing coil between the cylinder.  This antenna is described in the Demonstration #5 from Ted Hart.  

Building the antenna is very easy and inexpensive.  It has outperformed my other antennas (dipole made from two mobile whip antennas up 20 feet and a vertical w/o radials).  The first test was when I checked into the weekly ARES Net (Statewide ARES Ne for South Texas), usually have to check in from an alternate net control due to a weak signal.  The first night net control heard me the first time without any repeats.  I next checked into the Southwest Traffic Net with the net control in Hot Springs Arkansas without any trouble.  For a limited space antenna it appears to be doing a good job.

EH-Antenna_Dwg80MDownload

Materials:

2” PVC Sch. 40 Pipe – Home Depot / Lowe’s
Aluminium Roof Flashing (10” X 10’)Home Depot / Lowe’s
Short 2” PVC coupling (2)Home Depot / Lowe’s
Sheet Metal Screws #6 or #8 X 1/2”Home Depot / Lowe’s
2” PVC Cap Home Depot / Lowe’s
Brass Bolts/Nuts #6 X 3/4”Home Depot / Lowe’s
#14 Enamel Wire The Wireman (Internet)

Construction:
I drilled a small hole to start winding the Phasing Coil on one of the 2” PVC Coupling.  The will also be used to place the wire down the middle of the cylinder, making sure the wire will reach the bottom of the Tuning Coil (~ 5 feet).  Secure the winding using hot glue.  I made each item (cylinders, coils) and then assembled them.  It is easier to handle the smaller pieces than the large antenna. 

Component Parts before Assembly

I cut a 24” piece of 2” PVC pipe to be used for winding the Tuning and Source Coils.  I wound the Tuning Coil about 2 1/2” below the top of the pipe (when assembling the antenna this will be cut to maintain the dimensions of the antenna).  Wind 34 turns on this PVC pipe (the Source Coil will be installed later).   Add another two turns for tuning the antenna (it is easier to remove turns than to add them).

I cut two pieces aluminium flashing 8 1/2” X 30 1/2”.  This is used to make the cylinders  Cut 2 pieces of PVC pipe 36”.  On one of the pieces mark the pipe 3/4” from the end (top of the cylinder).  Bend the flashing around the pipe starting at the mark.  This will be the top cylinder.  Secure the flashing with sheet metal screws every 1 – 2”.  Drill a hole on the bottom of the cylinder (long portion) and mount a 8 X 32 brass bolt 1/4” above the end of the cylinder. Mark the other PVC pipe 1 3/8” from the end.  This will be the top of the bottom cylinder.  Secure the flashing to the PVC pipe using sheet metal screws.  Mount a 8 X 32 bolt 1/4” below the top of the bottom cylinder.  Drill a small hole just above the bolt (this will be used to route the #14 enamel wire to the inside of the tube).  Run the #14 enamel wire down the inside of the bottom tube.  This wire should be as close to the PVC pipe as possible.  Route the wire through the hole and mount to the bolt (remember to scrape the enamel off the wire before connecting to the bolt)

Install the top cylinder to the 2”PVC coupling with the Phasing Coil using PVC cement.  The aluminium flashing should be against the coupling (we will cut the bottom cylinder PVC to get the correct spacing).  Ensure that the end of the coil is lined up with the bolt.  Scrape the enamel off the wire and install on the bolt.  Put the bottom cylinder into the coupling for measurement.  The two cylinders should be 1 diameter spacing ( 2 3/8”).  After cutting the bottom cylinder to the correct dimensions, it is time to glue it into the coupling.  The bolt on the bottom should be mounted 180 degrees from the bolt on the top cylinder.  Measure the bottom end of the bottom cylinder and cut it off so the flashing is flush with the bottom coupling.  Glue the coupling in place.  Measure the pipe containing the tuning coil to the flashing for 1 diameter between the cylinder and the tuning coil.  Cut the pipe and glue into place.  Now we are ready to tune it.

Using the instructions in the Demonstration documents, tune the antenna. After the antenna is tuned, the source coil should be wound on the pipe and tuned per instructions.

EH_Antenna_Demonstration_5Download
EH_Antenna_Demonstration_4Download

Article by WB5CXC originally available at WB5CXC.com

10 meter Moxon Yagi Beam

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Article by WB5CXC

I wanted to build a 10M Yagi.  I looked at some of the options and decided on the Moxon after I built my 2M Moxon.  I designed the Moxon using the Moxon Rectangle Generator.  Do a search on the Internet to find the Moxon Rectangle Generator.  Enter the frequency and the size of wire and it will calculate the sizes for the Moxon Yagi

The main boom is made from 1 1/4” PVC sch. 40 pipe.  The ends are made from a 1 1/4” Tee, 1 1/4” X 3/4” reducing bushing, 3/4” PVC pipe, and 3/4” 45 degree elbows.  Make the end pieces first.  I put the ends together and measured where the spacing gets to 55”, then I cut the pipe (for the end to be 55”).  I then put he two ends out and measured th 150 3/4” and cut the pipe (be sure to leave enough room to slide into the Tee an still maintain the correct length). 

This document was originally available at wb5cxc.com

A 3 Element Mono-band Yagi for 20 Meters

Posted in Articles, HF Antennas Leave a comment

By Kees Wiegers,  PA5CW (ex-PA3BHS)

It looked impossible to get a large beam for 20 meters up a tower, but it was something I always wanted. So after attending a presentation by John Devoldere, ON4UN, of Merelbeke, Belgium, I decided to try and build my own beam.

At the presentation, John demonstrated software for designing Yagi antennas. From a collection of about 100 antennas you could choose the most suitable for your needs. I was interested in a compact beam for the 20 CW part of the band. If you choose a narrow bandwidth such as for the CW portion of the band, you can optimize gain and front to back ratio for that part of the band.

Continue reading→

Dave’s Homemade Loop Antennas

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Article by N2DS Dave

Welcome!

Welcome of my homemade loop antenna or loop aerial pages. All the loops described here were designed and built by myself. The features are not real different from loop to loop. These loops are made to enhance radio reception in the broadcast, or medium wave (MW) band range. Some of the loops are just one coil, some have tuning capacitors and some have an extra coupling coil. Read on and discover the fantasy of loop antennas. Or fetish in my case.

A Word About Loop Antenna Design

All these loops involve a resonant tuned circuit made up by a multi-turn loop coil and a variable capacitor. If you are using one of my designs shown on these pages, you are all set to go ahead. But if you are designing your own loop antenna, please read on.

As just mentioned, a resonant circuit is made with the coil and variable capacitor. The old standard configuration to tune the medium wave band is a 240µH coil and a 365pF variable capacitor. These numbers are fine when using a small diameter coil, but are grossly inaccurate with a loop antenna coil.

This inaccuracy is due to a relatively large amount of self capacitance (also called distributed capacitance) built in to large diameter wire coils. Increasing the wire spacing doesn’t do a lot to reduce this extra capacitance.

Continue reading→

Dave’s Homemade Antenna Tuner

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Article by Dave N2DS

A tuner like this has appeared with some of my high performance radios, such as my #35 and #50 sets. This type of tuner has worked very well with the accompanying detector board to make a nice dx crystal radio. My aim was to put as much versatility into this tuner project. When litz is this expensive, you can only go around once.

There are 4 uses I have found for this tuner. (This is why I call it a multi-use tuner.) The first use is a front end for my medium wave dx crystal or tube regenerative radios. Second is using the 4 gang capacitor with a loop antenna as a high performance crystal radio. Third is a long wave tuner and finally a signal booster for a nearby radio. Please look at the circuit below as I describe the different uses.

The medium wave (530-1700 broadcast band) crystal radio or one tube radio is set up by opening the two brass link switches between the capacitor gangs. The coil switches should be closed or shorted. By connecting an antenna and ground, this device becomes an antenna tuner. The signal is inductively coupled to the nearby crystal set detector.

The second use is to connect the tuner to a crystal loop antenna. To reduce circuit losses, only the stators of the capacitors will be connected. The links between the capacitor sections should be shorted together. Between the two sets of stators, the loop is connected. This can be done by using the A and G terminals. The effective capacitance is 500 pf. There is no wiper arm loss when using this 4 gang capacitor in that manner. The links to the coil should be opened.

The third use is for tuning in long wave stations. To tune the upper end of the long wave band, short all 4 links. If you wish to go lower, you will need a coil with higher inductance. This is easy to connect with this tuner. Open the two coil links and connect and external coil to the two thumb nuts that are now available. You will have 1000 pf capacitance across the coil and in series with the antenna available. Additional fixed capacitors may be used if a lower frequency is desired.

Finally, this tuner makes a great signal booster for a near by radio. I have had some e-mails from web visitors wanting to know how to make their little transistor radio work better. I did this in the 60’s when I wanted to put a transistor radio on my bike. The signal was weak so I made a tuned circuit and connected it to a rod antenna. Open the links that are between the capacitor sections and close the coil links. Connect an outside antenna and earth ground to the A and G terminals. Tune in a station, then reduce the volume. Then tune the tuner for a peak. You will be surprised! Just think how your kids can blast the house with Radio Disney with the same 10 songs all the time. Who Let the Dogs Out!!

Ok, now for the heißen eisen, the construction details. My tuner is built on an oak board about 16 x 5.5 inches (40×14 cm). The variable capacitor is a 4 section, 500 pf per section. If this is going to be used as a dx tuner, please look around for a quality variable capacitor. That is one with at least ceramic insulators on the stators. Nothing will kill the Q faster than a crappy variable capacitor. The capacitor should be mounted on ceramic or styrene standoffs.

It is also important to note that the capacitor shaft is isolated from the vernier drive with a plastic shaft. This is very important as this reduces the hand capacitance. There is still some slight hand capacitance effects which would be made better by moving the capacitor further back.

A 6:1 vernier dial drive is used to allow for easy tuning. Trying to tune the MW band in a half turn when using big litz is tedious at best. A one inch (24 mm) hole is punched in the front panel and the drive is attached with two small screws and nuts. Allow for the front panel or capacitor to move a little so as to reduce the binding. When the sweet spot is found, then the capacitor and front panel may be tightened. The dial is a round piece of thin styrene that is attached to the vernier. Made the dial as you please. I use Brother P-Touch labels to dress up my dial.

The switches are made up of brass links machined to span the distance between the two #8 screws. The panel material is styrene. Styrene has very good rf loss properties.

If you look at the switch drawings on the diagram, you will see a fixed side and a movable side. If the brass links are placed that way, the tuner will work as intended.

The coil form is a piece of 6x7x1/16 thick (152,5 x177,5 x1,6mm) styrene. There are 11 slits cut down to a hub diameter of 2 inches (5 cm). The wire is 660 strand, 46 gauge litz wire.

There is not too much more I can tell you about this project. If you have questions, please contact – Dave N2DS

Article originally available at http://makearadio.com

WSJT-X Site down: how to download.

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The official WSJT-X site is down from several days. The Website is hosted at Princeton Univeristy and it looks like it is under maintenance or relocating.

At time writing the only way to download the WSJT-X program is to access the SourceForge website where the files are maintained by the developing team.

Click here to download WSJT-X

Current stable release is  wsjtx-2.5.4 while release candidate version is 2.6.0.

Six Meter Yagi Antenna

Posted in VHF Antennas Leave a comment

A four element Yagi Antenna for 50 MHz band.

Six Meter Yagi

The reflector and the director elements can be mounted directly to the metallic boom, while the Driven element must be insulated from the boom.

The driven element is basically a simple folded dipole and foreseen a 4:1 balun. Usage of a folded dipole as driven element of the yagi antenna is almost common on VHF Yagi designs since it allow broading the SWR bandwidth.

If the broading is not so much important, the antenna can be directly feeded with a conventional dipole directly connected to a 50 ohms coax cable.

Mic Wiring Diagrams

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Article by m0ysu

Microphone wiring can be a real pain if you aren’t sure how to work out which wire goes where. On this page I will try to explain the basics and also give you the wiring positions for most CB radio’s

Basic Mics – These consist normally of three coloured wires and a braid/screen. The braid is the common wire for the TX/RX/Mod and is normally twisted around the modulation wire. If you get this in the wrong place you will be fighting an uphill battle. 4 pin mic sockets are about the easiest to sort out, the 5 pin din can be very hard to wire as there’s not much distance between the pins and can “short out” easily. Normally when I’m wiring 5 pins I put a sleeve on each wire to prevent this.
Back to 4 pin. Put the plug into the radio and look at the solder pins. Two of these pins will make the radio receive (sound) so find out which two these are by shorting a piece of wire across the pins with the radio on until you find the two that make sound.  One of these pins will also be common to making the radio TX so that pin will be where the braid is soldered to. Once that is soldered on its pin touch each coloured wire on the other pin until the sound returns. Solder that coloured wire on the other pin. Next you need to find the TX pin. With the mike key depressed touch the other two wires breifly on the TX pin until you find the one that makes it TX. Solder that wire to the TX pin. Finally the modulation wire will go on the remaining pin. Often the modulation wire is the yellow one or it has the braid wrapped round it.

 
PWR Mics – These normally have 4 coloured wires and a braid. More often than not the black and braid twist together and go on the earth pin. The blue goes on the Receive pin. Sometimes but less often the blue and braid go together and the black is RX.
Below I’ve made this a bit easier so you shouldn’t have to do the above unless the wires of the mic do not correspond with the below.


ALTAI PWR MIC – black/braid= earth, red=RX, white=TX, Yellow=MOD
ASTATIC – blue/braid=earth, black=RX, red=TX, white=MOD, Yellow=Spare
SIRTEL ECHO MIC CBE 2002 – black/braid=earth, blue=TX, white=RX, red=MOD
007 POWER MIC – brown/braid=earth, green=RX, white=TX, blue=MOD
SADELTA EC 980 – braid=earth, green=RX, brn=TX, white=MOD
                              or braid=earth, black=RX, blue=TX, white=MOD

OLDER MAKE OF CB   followed by plug reference

ACADAMY – 3
ALPHA 4000 – 13
AMSTRAD 900/901 – 1
ATRON CB 507 – 2
AUDIOLINE (ALL) – 2
BARRACUDA – 15
BINATONE 5 STAR/ROUTE 66/ BEAM BREAKER – 1
BREAKER 40FM CEPT – 1
CB MASTER 2040/2080 – 8
CHEIZA – 3
COBRA 146GTL/148/19/21 – 2
COLT 210/295/355/720 – 8
COLT 320/444/510/870/EXCALIBUR – 1
COMMTEL – 3
COMMTRON V111/CXX – 8
COMMUNICATOR – 1
DNT M40/B40 – 11
DOMINICO CONVOY 1 – 1
ELFTONE – 3
EUROSONIC EURO 2 – 5
FALCON FCB1281 – 1
FIDELITY 1000/3000 – 3
FIDELITY 2000/2001 – 1
FORMAC 88/120 – 1
GE 3-5804/3-5805 – 12
GECOL GT858B – 3
GRANDSTAND BLUEBIRD – 9
GRANDSTAND GEMINI – 10
GRANDSTAND HAWK – 1
GRANDSTAND HOMEBASE/WAGNER – 2
HAM CONCORD 2 AND 3 – 1
HAM EXPLORER – 1
HAM INT. UK/JUMBO/MULTIMODE/VIKING – 1
HARRIER CB/CBX/CBHQ – 1
HARVARD 400M – 5
HARVARD 402MPA – 1
HARVARD 420M – 1
HARVARD GOOD BUDDY – 4
HY-GAIN 5 – 1
ICOM ICB-1050 – 1
JWR MK2 – 1
JAWS MK2 – 8
KRACO KCB4030 – 1
KRACO KCB4004 – 2
LCL 2740 – 11
LAKE MANXMAN – 3
LEGIONAIRE – 4
MAXCOM 4E/20E/21E – 8
MAXCOM 30E – 1
MIDLAND 2/3/4/5/6/7001 – 1
MIDLAND 805 (PORT A PAC) – 14
MIDLAND 099 – 8
MURPHY CBH1500 HOMEBASE – 6
MUSTANG 1000/3000 – 1
NATO 2000/NATO 40FM – 1
NEW FORMAC 88 – 8
PEGASUS 7 – 1
PLANET 2000 – 1
PRESIDENT ADAMS/ANDREW J/AR144/AX144/DWIGHT D – 2
RADIOMOBILE CB201/202/205 – 1
REALISTIC TRC2000/2001/2005 – 12
ROTEL RVC 220/230/240 – 1
SAPPHIRE X2000 – 3
SAPPHIRE X4000 – 8
SCOOPER MKY440/550E – 2
SERPENT UK4000 – 1
SHOGUN (OLD) – 7
STALKER (ALL) – 2
SUN 401 – 1
SUPERSTAR 120/360/3900 – 2
SUPERSTAR 2000 – 1
TOKAI – 3
TRISTAR 727/747/777/797 – 1
UNIDEN UNIACE (ALL) – 2
YORK 861/863/869 – 1

Article by m0ysu originally available at m0ysu.com/micwiring.html

Compact 20m Yagi

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Article by M0DGQ

This yagi antenna is particularly suitable for those with small plots ( myself included ) who wish to use a 2 element 20m yagi. The design is by AB4GX, the original article is listed below ( PDF ). Here different materials have been used for construction as these are easy to obtain here in the UK other than this the design is essentially the same. The original design uses aluminium tube for the elements, common 2.5mm pvc covered wire is used here, this will reduce the useable bandwidth slightly but approximately 150kHz of the band is still useable – you will have to decide which part of the band the antenna is to be adjusted for. CW is my main mode on HF, so the antenna was adjusted for this section of the band. Here, both solid 6mm wire and 6mm mains earth wire were tried for the elements, however 2.5mm pvc covered wire ( stripped from standard domestic 2.5mm twin and earth cable ) is used in the final build as it is easier to use and cheaper. Four 4m telescopic fishing poles are used for the element wire supports, the final thiner section of the pole is disgarded. The wire elements are soldered directly to the loading coils and sealed with self – amalgamating rubber tape. The diameter of the fishing pole is approximately 23mm at the loading coil.

The element support mounting brackets are made from angle aluminium and are secured to the main boom by U bolts, the pictures give a clear view how this done. The boom is made from aluminium tubing, mine is approximately 50mm diameter and a wall thickness of 2mm – 3mm. The coax feeder is soldered directly to the driven element and insulated with self amalgamating tape, a four turn loop in the coax acts as a choke balun. As per the original article, the antenna should be adjusted at the height it is to be used at, this is tedious but worth the effort. In use, mine resides at a height of approximately 13 metres and gives a 1:1 SWR at 14 Mhz to 14.1Mhz rising to roughly 2:1 at 14.2 Mhz so you will have to decide which part of the band you want to adjust it for.

The antenna has been in use for several months now and the results have been very good, JA VK VE stations have been worked with ease. One observation ; because the antenna has quite a high Q, when wet due to rain the antenna resonance and SWR does alter somewhat but is still useable. It will be interesting to see what happens when frozen.

Article by M0DGQ originally available at http://m0dgq.co.uk (now offline)

Sudden TVI Problems – Solved

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Recently my apartment building decided to change the TV antenna system because of the latest upgrade of TV broadcasting to the DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial) standard.

My 10-year-old samsung LCD TV stopped receiving signals during last summer. Surprisingly, my TV was known to support the new digital broadcast signal, and also the shutdown of the old systems was already in place.

I therefore agreed to the antenna change, proposed by some condominiums.

The antenna installer, commissioned by the building manager, instead of changing the antenna, as I would have expected, decided to change only the antenna preamplifier, leaving me the old amplifier as a souvenir, and the box for the new amplifier.

Magically, my old TV went back to tuning all DVB-T2 channels correctly.

So far only the good news.

I then wanted to test my radio to make sure of the job done, since with the precendete amplifier, I could only jam the TV signal in certain frequencies, and exceeding the 200 W PEP.

Instead, to my immense amazement, I found that with only 5W of power on any HF band I could completely cancel the TV signal.

Terrified by this, and in disbelief as to what was going on, I began to document myself on the net and ask colleagues and in the fari forums.
Following everyone’s advice, I first informed the administrator, requesting a review of the amplifier, and then wrote directly to the Belgian manufacturer, of the TV amplifier reporting the anomaly.

The amplifier in question, about which I do not want to give bad publicity, is one of those self-programmable ones, very small, and evidently unshielded. The manufacturer immediately replied to me asking about the power output of my transmissions and frequencies, and saying that he would inform the technical department.

In the meantime I asked the administrator, for a replacement with another product that was shielded, and in fact in the following days the antenna technician, replaced the product with a TERRA PA420T and the problems magically disappeared.
Of course, this cost me the antenna specialist’s intervention to replace the TV amplifier.

A few days ago, I was contacted again by the Belgian manufacturer, even proposing to do a test with the modified version of their amplifier, to see if they had solved the problems. Of course, I declined.