Ham Radio Blog - IW5EDI

Kenwood TH-F7E vs ICOM IC-E90

iw5edi — Fri, 22 Feb 2008 22:42:19 +0000

I’m currently evaluating these two handheld transceivers and before to buy one I’ve tried to understand pros and cons of both rtx.
I will summarize here the work of my last two days, since I’ve not found any usefull review that could compare these two portable transceivers. Following comparison is the result of third party opinions i’ve collected on the net, so use this article with caution.

Dimensione and weight
They are pratically the same, Icom first introduced in the marked this model that many other have followed. Kenwood looks lighter.

Audio sound quality
Concerning the onboard audio speaker, Kenwood quality is amazing for clearness, really excellent.

Keyboard
Here ICOM works better, since Kenwood keys are very small and people with large fingers may find problems. Back lighting is good in both transceivers.

Ease of use
The Kenwood is extremely user friendly and easy-to-use. The icom is difficult to setup expecially for newbies

Battery
Both will output 5 Watts. Icom offer also 0.500W but the Kenwood offers also the 1.5 W ! Batteries have same amperage, but kenwood outperform for battery duration and recharging time, only 6 hours vs 12 hours of the ICOM

Antennas
Both comes with their antenna, tuned for the bands they need to operate.

Transmission coverage
ICOM is much better here, since cover 50/144/430, while TH-F7E is limited to 144/430

Reception coverage
Kenwood, outperforms Icom since allow 0,500/ 1300 Mhz while Icom cover only 0,500/999.
Kenwood TH-F7T allow you to listen in both frequencies simultaneously ( dual watch ) Both works in FM/AM/FM-W but Kenwood allow also LSB/USB/CW !

Price
Here in europe price is almost comparable for both transceivers, at the moment of writing this article, flows from 250-350 euros, depending on special prices and offers.

IRAQ: Ham Radio operators keep hobby alive

iw5edi — Wed, 16 Jan 2008 23:39:54 +0000

An interesting article on Iraqui amateur radio operators condition has been published on the Los Angeles Times.

Many Iraqui hams have dismissed their stations because initially either US troops and Iraqui police were supicous that their transmissions are a tool of the insurgency. During the Saddam period however looks like things were not so much better.

It seems things has changed now, and in an interview to YI1AK YI1EYT and YI1FLY, express the desire that other operators could go back to their radio shacks.

According to the Iraqui amateur radio society many more callsigns has been issued to foreign people in the last years.

Article worth reading

Iraqui Amateur Radio Society

AMSAT UK Site Hacked !

iw5edi — Sun, 16 Dec 2007 15:02:57 +0000

Surfing the net this evening, I jumped into the AMSAT UK site looking for satellite informations. The site reuslts hacked as you can see in above picture.
A quick jump to archive.org revealed that the amsat site has been implemented using Joomla a popular open source content management system that too very often release security fixes that needs to be applied as soon as they are availble.

Yaesu to be acquired by Motorola !

iw5edi — Mon, 05 Nov 2007 23:20:12 +0000

Motorola announced today the intention to acquire 80% of Yaesu parent company Vertex Standard.
Current owner will remain with 20% forming a joint venture.
Who knows if this merge will offer Yaesu technical development new founds and resources to be implemented in next generation Yaesu products, or if this merge will sign the decline of one of the oldest firms in the ham radio market ?
Should Icom look around for other similar joint ventures ? Who knows…
Good luck Yaesu.

DXTuners is back

iw5edi — Mon, 05 Nov 2007 07:12:32 +0000

DXTuners is back online. After this spring shutdown, looks like the system is starting up again, maybe thanks to Kelly SM0NHC or maybe not. This is not clear yet.
Looks like this new system will host selected remote stations only and subscription will be free of charge.

Ham Fest Firenze Pictures

iw5edi — Sun, 14 Oct 2007 21:02:17 +0000

The last week-end in Florence took place the first electronic and ham radio exposition, managed by compendiofiere.
I’ve been there both days, the first one I got the opportunity to met PY1NB Felipe, who was here in holiday with his family. The second one, i came back to buy the LDG Z-100 automatic antenna tuner for a very competitive price.
There were 6 amateur radio shops and there could be more, but an electronic show in Arezzo taking place in the same week-end took away a couple more stands.
Local ham radio operators, had a free pass for the exibition and this has been an apreciated gift from the event organizators. A free trade-exchange maket missed, but hopefully the next year we will have this too.
Some more pictures can be seen here at local ARI radio club web site.

Technorati Tags: ham radio, hamfest, amateur radio, firenze, florence

The 40 meter Stealth Vertical

iw5edi — Wed, 19 Sep 2007 21:32:02 +0000

As published in antennex Dec. 2001
The 40 Meters band stealth vertical antenna by K7ZB

“You’re 30dB over 9 here…” So goes the consistently fine signal reports received from around the USA and beyond - on 40 meters at the peak of Sun Spot Cycle 23. The most common antenna used in ham radio mounted over poor desert soil conductivity still performs beautifully!

This is the view of our second floor deck as seen from the closest street. The need for a 40 meter antenna that would perform well and not violate the spirit of the Home Owner’s Covenants protecting the aesthetics of the neighborhood was the driving force behind the design of this vertical.

This antenna was designed to provide low angle radiation for good DX performance during the night time hours. DX on 40 meters is best when the local sun is down and this makes it convenient to use the cover of darkness to hide the size of a quarter-wave antenna. Especially one which is mounted 12 feet above ground which puts the top of the vertical at nearly 50 feet!

The basic concept is to mount a standard 1/4 wave vertical element on a swivel mount, secured to the deck railing. The mounting must be extremely secure when the antenna is in the upright position. It should also be easy for one person to put up or take down in less than 5 minutes. This design meets these criteria with excellent results.

The 40m vertical in its down position rests along the bottom of the far side deck railing. It is supported by plastic coated hangers of the type sold in hardware stores for hanging bicycles, etc, on garage walls. These hangers also make excellent supports for the antenna in the intermediate position for extending the telescoping top section and for supporting the vertical in the upright position.

Shown below is a view of the vertical with the telescoping top 5′ section removed and stored in the down position. The swivel assembly has a spring-loaded locking pin which secures the base in either the upright or down positions. Putting up the antenna is simple: the top section is secured with a wing nut then the vertical is walked up hand-over-hand into the upright position and locked in place with the pin. The hanger also stabilizes the antenna so it does not sway in light wind.

The swivel assembly has been modified to support the vertical base element. Its load rating is well in excess of the load imposed by the vertical. Since the 35′ - 7 1/2″ vertical is only intended for use during good weather conditions it is only guyed with two light guy lines to ensure that in case something did happen to the antenna while up, it will not fall across neighbor’s property. In our neighborhood there are no above-ground wires for power, cable TV or telephone, so there is no possibility of a crossed-wire mishap. The coax attachment is made through an SO-239 connector mounted on an acrylic plastic block drilled and U-clamped to the base tubing. Also visible are the two radials connected to the shield of the coax connector. The two radials are 33′ long, and slope from 12 to 7 feet above ground at their end. They slope because that’s the available tie point height in the yard. The radials are oriented 145 degrees apart - not quite the 180 degrees desired but close enough. The EZNEC antenna azimuth plots do show the minor skewing of the pattern due to the asymmetric radial placement, but this has little effect on its performance.

The net active dimensions (not including the length inserted into lower elements) for each element of the vertical are as follows:

Base element: 11′ 5″ (1 3/4″ Dia. Al tubing)
2nd element: 10′ 2″ (1 1/4″ Dia. Al tubing)
3rd element: 5′ 7″ ( 3/4″ Dia. Al tubing)
4th element: 4′ 11 1/2″ (1/2″ Dia. Al tubing)
5th element: 3′ 6″ (3/8″ solid Al rod)

The tubing diameters were based on what I had available. Good mechanical design technique should be used in attaching each element securely into the lower one.

This antenna does bow substantially when being put up and down. This droop could be minimized by going to a higher strength alloy. The best strength-to-weight ratio for vertical tubing is probably titanium-aluminum alloy, although it costs substantially more than the material I used.

Raising and lowering 35 feet of aluminum tubing up over one’s head in low light conditions leads to safety considerations. I wear a hard hat and safety glasses when raising or lowering the vertical.

Shown below is a night-time photograph of the vertical in the upright position. The stabilizing hanger is seen approximately 2′ above the swivel assembly. Notice a 6 turn coax loop in the line which serves to help keep RF out of the shack - which is about 20′ from the vertical. The RF exposure on 40 meters with 500 watts output is within the FCC’s Maximum Permissible Exposure limits.

An advantage of verticals mounted above ground like this one is the safety aspect of proximity to RF-hot radial wires or vertical elements. Our yard is walled and the RV gate kept locked, and the access out to the deck is past my operating desk - so there is little danger of anyone’s unexpected exposure to hot wires.
Brian KD7Z helped with the design concept when he directed my attention to a Hints & Kinks article in QST (May 2000, page 56) that featured the fold-down mobile-antenna mount design of KB5YA. It was this use of the swivel jack that led us to conceive its use for a deck-mounted 40m vertical design.

Dave provided EZNEC computer simulations for the vertical dimensions used here, which when implemented were right on target.
The photo is of the vertical in daylight - up just long enough to take the picture to show how it looks at night! You can faintly make out the guy lines and one of the radials running out to the spot where I was standing to take this picture. Above the doorway on the deck is the coax feedline to the center insulator at the eave under the roof peak for the 75m antenna.

An excellent reference for understanding vertical antennas is provided by L.B. Cebik, W4RNL. Dr. Cebik is an authority on antennas and his website contains a vast amount of excellent information. The webpage specifcally covering verticals is shown below.

Original article by K7ZB

Originally available at pages.zdnet.com/radio_k7zb/id8.html

Technorati Tags: ham radio, antenna, amateur radio

A new HamFest in Florence 6-7 Oct.

iw5edi — Thu, 13 Sep 2007 20:37:43 +0000

After 20+ years, a new Ham Fest will take place in Florence this year.
Compendio Fiere, one of the most active hamfests managing company, has established the FIERA DELL’ELETTRONICA COMPUTER E TELEFONIA in Firenze.

This is mainly a Computer Electronics and Phone exposition, where also amateur radio will be present with six national ham radio dealers. This event will represent an interesting opportunity to promote Ham Radio to the many young people that will surely attend the hamfest, even if with a different goals.

The location of the hamfest, is in the Florence center in a dismissed railway station named “Stazione Leopolda”. Driving direction can be found via this link, but I suggest to use the Firenze SMN Railway Station and arrive by train. Car parking in Florence is very difficult, particularly during the week-ends. I suggest to use the Fortezza da Basso or Railway Station car Parkings. Feel free to write me if you need assistance.

Technorati Tags: firenze, ham radio, hamfest, florence

An effective 10-20m DX antenna for deed restricted lots…

iw5edi — Sun, 09 Sep 2007 23:12:58 +0000

Original article by K7ZB

Results

The simple 15′ vertical antenna shown mounted on the railing of our second floor deck has produced almost 200 countries worked around the world… VQ9’s in Chagos and 3B8’s on Mauritius in the Indian Ocean, TX0DX on Chesterfield Reef, VK0MM on Macquarie Island in the Antarctic region, BQ9P on Pratas Island off Taiwan, ZM7ZB on Chatham Island in the South Pacific along with FO0AAA on Clipperton, 9M0OO on Spratly Island in the South China Sea, JT1CO in Mongolia and on and on. What I hear, I can usually work with this little wonder and the small size and profile make it feasible for use in deed restricted neighborhoods.

A radio amateur friend and antenna designer came up with a simple design for a 10 meter vertical, which another friend and I modified to make work for the 14, 18, 21, 24 and 28 MHz ham bands. Its performance surpised us, and I’ll share it with you, in case you too are looking for a simple, inexpensive DX antenna that really performs well.

Main Antenna Concept

The basic concept is to put up a piece of aluminum tubing with a telescopic section held by a small hose clamp to adjust the height. By attaching the center conductor of a coax feedline to the tubing, and the shield of the coax to a couple of radials from the base of the tubing you can load the vertical across quite a broad range of frequencies.

Of course, with a vertical element of approximately 15′ this is a non-resonant antenna for the 10, 12, 15, 17 and 20 meter bands. I chose this length on purpose to allow the system to be tuned to resonance with an antenna runer.

Tuning

Since the SWR in an antenna system of this type will be relatively high, an antenna tuner unit will definitely be required. You may need an external ATU if the one in your transceiver can’t handle the impedance mismatches involved. Here at K7ZB, I drive my TS570 (which has a built-in ATU) thru the amplifier, which then drives a high power ATU to the antenna. I put the SWR/Power meter between the amplifier and ATU to ensure a good match for the amp, and in cases where I run barefoot without the amp, I can still use the ATU to assist the transceiver’s ATU in ensuring a good match.

In this way, everything is matched for maximum power output: from the transceiver to the amp, and amp to the antenna. And, even though the SWR’s are high at the feedline and the antenna, it doesn’t matter because the system is matched with the ATU.

Mounting Scheme
The picture below shows the details of the mounting scheme.

This picture shows the center conductor of the vertical connected to an SO-239 female coax connector. I used two pieces of insulated #14 AWG solid copper wire to provide a stiff means of supporting the connector to the metal bracket. Note that there is no true ‘ground’ connection to this antenna. The ground side of the connector simply connects to the hardware bracket, to which the two radials are connected. The bracket looks like a simple piece of offset metal used to mount a small flag pole or the like.

The two ~15′ radial wires are held to the bracket with a large sheet-metal screw, so the bracket is connected to the coax shield. Electrical isolation from the center conductor of the coax connected to the vertical element is provided by an insulating rubber sleeve. This is a piece of neoprene fuel line chosen because the dimensions fit the aluminum rod inserted into the lower 14″ of the aluminum tubing. However, we found the electrical isolation properties of neoprene fuel line leave a little to be desired at the high SWR’s of this system. After driving this vertical with 500 watts at high SWR in the middle of one of the DX Contests, I punched through the insulation. Obviously the original 10m antenna design was intended for lower power and lower SWR’s! This problem was solved by wrapping the neoprene sleeve with several layers of Teflon tape (the kind you buy for plumbing work at the hardware store). I also added a couple of layers of electrical tape (600V rating) for additional safety. These modifications are shown in the picture below with the vertical tubing removed - you simply add the tape over the sleeve. The vertical element is then secured to the bracket by a pair of hose clamps of suitable size.

A construction detail shown in the picture below is the solid aluminum rod that fits inside the lower 14″ of the main 8′ length of tubing. The solid rod is inserted at the bottom to ensure a good tight connection for the sleeve. This rod end can be drilled with a blind hole for a self-tapping sheet-metal screw to secure the solid copper wire from the center conductor from the SO-239. The tubing is secured to the rod with a hose clamp just above the top of the bracket.

A tip for ensuring good clamping force with hose-clamps and hollow tubing is to slit the tubing about two inches up from the bottom on opposing sides with a hacksaw. This will allow the clamps to grip tightly enough to prevent slippage. Also, insert a solid piece of rod about 8″ long inside the smaller diameter telescoping tube at the top of the vertical to prevent that tube from collapsing. The upper telescoping tube is adjusted to about 15′ overall length to give proper loading across all bands.

The final photo below shows the completed vertical attached to the railing with the coax looped about 6 times to give some measure of RF choke action to keep RF from entering the shack on the braid. I secured the coax loops with plastic wire-ties to the railing support to stress relieve the connector. You can also see the tubing and small hose clamp just above the neoprene sleeve along with the two larger hose clamps gripping the sleeve and rod to the bracket.

It is quite easy to remove the vertical tubing element and stow it when you are not operating, as I now do, thus fulfilling the need for an unobtrusive HF antenna.

All in all, a cheap and effective radiator for the higher HF bands!

Article originally available at pages.zdnet.com/radio_k7zb/id8.html.

Technorati Tags: antenna, hamradio, dx, vertical, coax antenna

DXTuners.com shutted down

iw5edi — Wed, 29 Aug 2007 21:38:20 +0000

Today surfing the net looking for ham radio live streaming, or remote controlled radios, I’ve jumped into dxtuners.com. Sadly, I’ve been redirected to new Kelly Lindman blog, where he annouce that his dxtuners.com has been shutted down by himself due lack of interest and time.
I’ve been an estimator of Kelly’s work since 1998 when DXTuners was named JavaRadio.com. (he had to change name some years after due to a SUN explicit request, cause of Java prefix name and itìs copy rights…if I don’t get wrong).

JavaRadio has been one of the first, or maybe the first attempt to link the internet with ham radio in a different way, allowing net surfers, to remotely tune a radio and listen the output via a live audio stream.

During years Lindman (SM0NHC), who is an IT expert, developed the client / server architecture using the emerging Java technology, and established a network of remote tuners all over the world. The network included stations from almost all continents, I remember the first remote tuners from Perth Australia, or Illinois USA, Lancaster in CA USA , Edinburgh Scotland, and a couple in Sweden… to support the project costs he was asking a yearly fee to get full access to the network, and with that requirement, I lost interest on that website, since it was exciting to tune remote stations, but not enought for me to pay a fee.

According to some news I’ve found, Lindman has not been able to delegate his functions to anyone else, and in May 07 decided to close the dxtuners.com.
I’m sorry to see a cool web resource, and a so valuable work (I refer to his Java System) be lost, but it can happen when things are driven only by passion, expecially if passion run out.
BTW TNX Kelly
73.

Want to try some remote receivers online? In the mean time, someone else has arranged a remote tuner control via the web, for free… try a google query for Online Radio Receivers

Technorati Tags: dxtuners, shortwave, hamradio, dx, online receivers, remote tuners, amateur radio