AmateurRadio.com

I’ve seen a couple of stories about this video already, so I figured I would post it too, and get Randy a little more traffic to the YouTube video. Randy headed to Petaluma, CA, and hung out at the TWiT Brickhouse with Bob Heil, K9EID and Leo Laporte, W6TWT, for the first day of the new Ham shack in the Brickhouse Studio.While Randy was there, he of course recorded some video and shared it with everyone else. There was also a special event station on the air for the open house, which I talked about last week. I’m curious if anyone who reads me, also worked the special event? If you did, please share in the comments. I would love to hear how it went. But now, Lights! Camera! ACTION!

73.

Rich also writes a Tech blog and posts stories every Tuesday and Thursday on Q103, The Rock of Albany’s website, as well as Amateur Radio stories every Monday thru Friday here on AmiZed Studios.

Rich Gattie, KB2MOB, is a regular contributor to AmateurRadio.com and writes from New York, USA. Contact him at [email protected].

The G4ILO APRS iGate is off the air again. My Android smartphone is on its way back to Motorola for repair so for the time being I need to use the Windows Mobile as a phone again.

I’ll also be running APRSISCE on it as G4ILO-SP while travelling to and from radiotherapy treatment in Carlisle. That is so that Olga can look at aprs.fi and see when I am about to return home. As I am using the volunteer hospital car service, time and route can be somewhat variable. APRS does have its practical uses…

Julian Moss, G4ILO, is a regular contributor to AmateurRadio.com and writes from Cumbria, England. Contact him at [email protected].

Jumping out of a fully working airplane from 13,000 feet is not exactly my cup of tea. When I stand to high on a ladder I get a little woozy. But this guy jumped from an airplane and using 70cm Amateur Radio Television, shared ti with other Hams. Mark, AF6IM, strapped on a parachute, and a 427 MHz ATV transmitter hooked to a helmet cam and jumped from an airplane to land safely while he transmitted, using a Drake mini-modulator with foldable dualband J-pole, that he released after his chute opened and he floated down to the ground.

As you can see from the video below and the info Mark gave about the jump, the Drake can act as a transmitter when an antenna is hooked to it, but the signal was weaker then expected and only worked when he got to about 2000 feet. He said he may try a linear or use a 5 watt Videolynx ATV transmitter next time he does it.

Mark was transmitting on 421.25MHz or cable tv channel 57, and the recieving station was using a 3-element 70cm UHF antenna connected to a Sansui TV set with built-in VHS deck set to catv channel 57. Improvements are being looked at from what was learned from this jump, and another may be in the future.

If you want to find out more, you can visit the Parachute Mobile website.

Rich Gattie, KB2MOB, is a regular contributor to AmateurRadio.com and writes from New York, USA. Contact him at [email protected].

The amazing power of the WSPR mode to enable weak signals to be received over long distances was demonstrated conclusively when my 2 watt signals, transmitted into a 1.3m long telescopic whip antenna from inside the G4ILO shack,were received in Australia and the USA, not once but several times with SNR reports of up to -19dB.

These spots were not achieved using a hand held radio as they occurred early in the morning when I was asleep. But they were made using a home made portable 30m whip antenna that I designed to be used with the VCXO-AXE portable WSPR transmitter I recently built. Here is a picture of the antenna taken during the tests.

The antenna consists of an L-match mounted in a small plastic project box, with BNC sockets for the transmitter and the whip antenna.

The constructional details can be gleaned from this internal view here. Click the image to see a much larger version.

The loading coil consists of about 46 turns of 28SWG wire on a T80-6 toroid. The matching capacitor is a 4 – 40pF trimmer. The number of turns was determined empirically (i.e. using trial and error) so don’t ask me for details of how to make one for other bands. There may be formulas for calculating things like that but I don’t know them.

It would have been difficult to make this antenna without an antenna analyzer like my RigExpert AA-200 which displays the SWR across a range of frequencies graphically. With my first attempt at the inductor it was possible to obtain an SWR null at 10.140MHz but it was rather a broad dip and the minimum was around 3:1. However at lower frequencies I saw that I was able to obtain a much deeper, sharper null. This made it clear that what I needed to do was remove some turns until the deep, sharp null was at the frequency I wanted. A deep null indicates higher Q and therefore better efficiency.

You can see the SWR curve of the final version below.

Note, however, that this was taken inside the shack in the test position where reflections spoiled the SWR and broadened the dip. When measured out of doors the SWR curve dipped deeper and was narrower as long as I stood clear of the antenna. (It was interesting to note how the SWR was affected even if I was a metre away from the telescopic whip. This suggests efficiency would be adversely affected when used in true hand held fashion.)

A good ground or quarter wave counterpoise wire is needed with this antenna. The resonant frequency is affected by the ground system used as well as the length of the whip and the position of the trimmer. If you don’t want to take an antenna analyzer to the field to check and tune the antenna before operation you should use the same counterpoise. So it would be advisable to pair the counterpoise with the antenna.

Further tests would be useful to determine the extent to which a good match is reproducible in different locations using the same whip length and counterpoise without retuning.

In case retuning is needed I added an access hole for the tuning trimmer. The resonant frequency can also be changed (increased) by shortening the telescopic whip a section or two.

This has been an interesting project. As a result of it I now have a completely portable, pocketable, battery powered system capable of sending a radio signal half way round the world, and I have developed a useful monoband 30m antenna.

Julian Moss, G4ILO, is a regular contributor to AmateurRadio.com and writes from Cumbria, England. Contact him at [email protected].

The code-writing squirrels at Radio Artisan Labs have produced another update to the Arduino Keyer code. This update provides a plethora of functions for the PS2 keyboard feature, increases the number of memories to 12, and the number of supported transmitters to six.  I’ve never encountered the Ultimatic mode in the wild, but it’s now available as are Iambic A, Iambic B, bug, and straight key modes.  Ham Radio Deluxe can now talk to the keyer, which can be used to provide a rather nice graphical user interface to most keyer settings and functions.  A host of other logging and contest programs should interface with it as well as some kinks in the serial USB interfacing were worked out.  And as if that wasn’t enough, the code now sports a GNU license like all good free software should.

The next features to be developed are an LCD display with eight soft keys and CW receive capability.  The squirrels want to write some code that will automatically make QSOs while they’re on a DXpedition vacation in Aruba, wanting more time on the beach and less in the shack.

Front mounted

In a prevous post I gave account of my Elecraft AF1 mini module audio filter project.I have built other mini modules from Elecraft such as the DL1 dummy load, N-gen wide band noise generator and the XG-2 three band test receiver test oscillator. All of the kits went together very well and they all without exception came with very easy to understand instructions. I have put these kits to get use while building many of the Elecraft radio kits. These test devices can also be very useful around the shack to do many tests as you either build , test or trouble shoot many pieces of shack equipment. The only beef I have with all these kits is Elecraft does

Stand offs mounted

not offer enclosures for them. My DL1, N-gen and XG-2 are still on the bench without enclosures. This does not concern me to much as they are out of the way and in a safe place and out only during use. On the other hand the AF1 audio filter is going along side my KX1 in
many out door situations. It was a must to get this unit in a case. This brings me to Dave W8FGU he offers a very good solution to my AF1 case situation. Dave

Tab on rotary switch bent

offers clear Lexan enclosures for a variety of Elecraft products. Dave's site offers great pictures of the enclosures that he offers. This solved my problem of wanting to make sure the AF1 filter was protected as I transported it and used it out doors. I contacted Dave and ordered the product, I received emails on the status of my enclosure. It was promptly shipped and arrived in no time. The enclosure was very well packaged and I downloaded his PDF instructions as there are some very slight modifacations to be done to the

Bottom of enclosure

Battery mounted on bottom

AF1 for it to fit properly into the Lexan case. The 9 volt battery had to be mounted on the underside of the circuit board. That went very smoothly as Elecraft has provided for this and it is well laid out on the PCB.
The only other modification was the AF1's rotary switch had a tab which had to be bent down in a horizontal fashion.The case is very well made and along with the strength of the Lexan materiel makes the case well worth it. All edgings and corners were flush fitting, all the screw holes lined up with professionalism and attention to detail.

Finished product

Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

As I recently blogged, I purchased the DV Access Point Dongle a few weeks ago.  It really came down to trying to do something to enhance my interest in D-STAR or sell my ICOM IC-92AD.  I was first introduced to D-STAR back in early 2008 and purchased the IC-92AD in the fall of 2008.  I spent the first several months having QSO’s on the local repeaters with the growing number of D-STAR users in the Rocky Mountain region.  But I’ll admit I did get a little bored with just speaking with the same group of guys.  I mean no disrespect, but I never really got into the local VHF/UHF repeater scene.  I think I would have more interest in local repeater operation if I had a longer commute.  But with less than 5 minutes in the car, there’s just no time to try. 

Anyway, a few months ago I grabbed the D-STAR radio and re-educated myself on how to use it and connected to the local Denver repeater and connected to the REF005 London repeater. I really enjoyed just listening with that reflector dialed up in the background.  Not wanting to tie up the local repeater just for my enjoyment, I began looking into the DV Dongle and the DV Access Point Dongle.  I was first leaning towards the DV Dongle as I figured I would do more listening that actual talking and it could just play in the background.  I could use my IC-92AD when I wanted to QSO.  But as I began comparing the two dongles (no dongle is created equal) I began leaning more towards the DV Access Point Dongle with the ability to still use my radio. 

It didn’t take long before I had a short list of ideas on how the DVAP would come in handy around the house and in the office.  In the office I work in a lab which is a RF black hole.  Nothing comes in and nothing gets out.  I could take the DVAP and my IC-92AD to the office and either just listen or perhaps even strike up some QSO’s during lunch.

If you’re not familiar with the DV Access Point D-STAR Dongle, it is a simple looking little device that connects to your PC via USB and allows you from your D-STAR radio to connect into the D-STAR network via the Internet.    The DVAP has a small antenna and transmits at a mere 10mw.  But the nagging question was just how far will 10mw travel?

I had read many blog postings from other hams who were enjoying the world of D-STAR from their DV Access Point.  They were finding out they could successfully operate from other rooms, the back deck, the back yard and even to the henhouse as in the case of my friend, Tim Kirby G4VXE in the United Kingdom.

Now before I go any further, allow me to type out some fine print.  The DV Access Point Dongle is truly designed to provide a licensed ham the ability to connect to the D-STAR network from inside and around their home or location.  It is not intended to be used as a neighborhood D-STAR repeater and send RF signals across the neighborhood or across town. 

Having said all of the above, I still wanted to know the range.  My ham shack is in my basement.  With the DVAP setup and using the little stubby stock antenna, I tested by walking all around my basement, then going upstairs to the ground level, then upstairs to the second floor and then finally on my back deck and courtyard.  No issues.

Like many, the experimentation aspect of the hobby is something I enjoy.  I don’t have a lot of time to build radios and living in such an antenna restricted neighborhood, I don’t have a lot of need to build and experiment with antenna design.  So my eagerness to know just how far I could move away from my QTH really excited me.  I know I’m a nerd…but if you’re reading this so are you.

So I decided to connect the DV Access Point Dongle up to my Diamond X-30A external VHF/UHF antenna.  This antenna is attached to the side of my house where a Directv satellite dish once was mounted.  The antenna works great for working the front range repeaters (including the D-STAR repeaters) and I’ve also managed to hear ARISSat-1 via this stationary antenna.  As a point of reference, the antenna is approx. 16 feet off the ground and it does not stick up above the roofline.  It is totally hidden from view of neighbors and as such it not as efficient as it could/should be.

With no other modifications to the DVAP, I connected it to the external antenna and hopped in the car to go to the grocery store.  From my QTH to the grocery store parking lot (based on Google Earth measurements) as the crow flies or the RF travels, it is .75 miles, 1.20 kilometers, 3,941 feet, 1201 meters…I think you get the idea.  I honestly figured I wouldn’t make it out of my neighborhood.  As I reached the end of my street I was able to do a successful echo test.  I continued up the road and to the exit of my neighborhood.  Another echo test proved successful.  I then proceeded down the street towards the grocery store and with IC-92AD in hand and in the car I did another successful  echo test.  I reached the grocery store parking lot, stepped outside and conducted the final echo test….yep successful.  I was .75 miles from my QTH and had solid copy on the echo test to the DVAP dongle.

Again…let me add the fine print.  The DV Access Point Dongle is intended to provide the licensed amateur radio operator access to the D-STAR network in and around their house/yard.  It is not intended to provide connectivity at 3/4 of a mile away. 

I was short on time this particular day and plan to conduct further testing to determine the limit.  The neighborhood I live in is relatively old with tall, mature trees.  Another test in the dead of winter might also prove to provide additional range since less foliage on trees will get in the way.  A final testing to just fulfill my interests will be as far as I take the range experiment.  I’m not interested in trying to amplify the 10mw signal as I believe that is taking the DVAP in a direction not intended by its developer.  However, the next time I go to the community pool which is located just about 100 yards from my QTH, I believe the IC-92AD might just come along.

Look for an updated blog post on the additional range testing to see if I can go a full mile.  I’ve read reports from hams in the NY area who have been successful at one mile in all directions (N, E, S, W).  I may just wait until winter to try this as I stated above. Finally, I do want to do a little testing to see just how this setup could perform in a portable setup using an AT&T 3G data card.  I’ve certainly read blog posts from other hams stating they have had no issues with a configuration like this.  Again, it’s more to fulfill my experimental interests. 

Until next time…

73 de KD0BIK

Jerry Taylor, KD0BIK, is a regular contributor to AmateurRadio.com and writes from Colorado, USA. He is the host of the Practical Amateur Radio Podcast. Contact him at [email protected].