NE-FL D-STAR System

The Journal of the North East Florida D-Star Repeater Network

Archive for category Antennas, Feedlines and Duplexers

FPCARC repeater upgrades

Feb 24

Posted by mikelee in Analog Repeaters, Antennas, Feedlines and Duplexers | No Comments

Tim and Phil were at the hospital yesterday and swapped out the repeater RF deck, but it appears that the duplexer might need to be tweaked. In order to minimize downtime, Phil has pulled of of our spare duplexers and we will get that set-up for the FPCARC frequency at 146.715 in order that it can be swapped out in a very short amount of time. That will give us a chance to put the old duplexer on the bench and see if there are any other problems with it besides tuning issues.

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Stay tuned for more updates

Portable, Light-Weight REEL Dipole Antenna

Nov 23

Posted by mikelee in Antennas, Feedlines and Duplexers, HF Antennas and Operation, Kit Construction | No Comments

THIS is the classic – but unfortunately, it has been out of production for more than 25 years. Ahh… the bye-gone days, when high quality items were not terribly expensive, but built to last..!!  The Collins TD-1 was functionally identical to the HyGain 18TD.

I used to have HyGain 18TD – a great, portable antenna which contained two stainless-steel measuring tapes which could be extended into a dipole configuration. Unfortunately, nobody makes that antenna any more (MFJ/HyGain – are you listening..??!!) – because I think they’d sell a bunch of these to ARES organizations around the world if they did. Why in the world I either sold or lost that Hy-Gain antenna is beyond me..!!

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There have been many valiant efforts to duplicate (read : CHEAPEN) the design – some using yo-yo’s or the equivalent of Coleman Camping Clothes-lines. but they’re all quite fragile or in some cases quite large. So I was thinking – how could we make a sturdy, yet light-weight antenna that didn’t require extensive fabrication – that could be duplicated by almost anybody for less than $120..??

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Here’s my idea – and y’all are welcome to take it, steal it, improve on it, then share the results with all of us so that we can all benefit. Basically, it starts with two FLY-Fishing Reels – stainless steel in construction so as to be impervious to the weather, a fishing rod like a Black Widow which extends to 10-feet and a 1:1 balun which acts as our feed-point and coupling device.

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I used (relatively) inexpensive Fly Reels (Hobbs Creek HC-III Reels from Bass Pro Shops for $39.99 each) which are silky smooth and made of alloy, so they’re only about 5 oz each.What’s nice about these reels, compared to super-cheap versions, is that they have replaceable reels, so you could have a set of reels that had #26 wire and another set that has #18 for longer lengths. Of course, two reels are required – one for the left and the other for the right side of the dipole. Thus far, we have $80 in the two reels.

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Next, we need the center support for the antenna – but also it would be good to have a 1:1 balun, so I decided to find a balun that would accept a PL-259 from the coax, then terminate in BINDING-POSTS for easy attachment of the antenna wire. I just happened to have an LDG Electronics 1:1 current balun handy (never used it before) so I put it to use in this project. Of course, that means that this particular antenna will need to be a symmetrical dipole – equal length on each side of the center.

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I’ll also make a version of the antenna as an Off Center Fed Dipole (OCFD), so I’ll need to use a 4:1 balun – again, I just happened to have an LDG balun that could be put to good use. An LDG 4:1 voltage balun is ideal for this project and should provide an excellent match for the OCFD. Both these baluns are only rated at 200wCW, so be careful – but as long as you’re not QRO with an amplifier, all should be fine. Below are pictures of both baluns. Current cost is about $30 each for either of the baluns.  Also be careful since neither of these baluns are weather-tight, so don’t use them during inclement weather lest you short them out. Total cost now is about $110.

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Okay, so we have the reels for winding the wire, as well as the baluns – so now we should decide on the wire type and size. I will be using two sizes of wire – #26 copper clad steel wire with a black insulation which is virtually invisible and a #18 copper clad steel wire without insulation. The #26 is invisible from a distance greater than about 10 feet – so it’s ideal for “sensitive” locations (remember, these are temporary, since the balun is not waterproof).

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Wire size (diameter), in part determines VSWR bandwidth – the larger the diameter of wire (or tube) the greater the bandwidth – therefore the #18 wire will have substantially greater bandwidth than the #26 which I expect to be quite sharp when being swept with an antenna analyzer. I’ll provide comparative VSWR plots from the AIM/UHF Antenna Analyzer when I get some time. It will be interesting to see the difference caused but the wire gauge. I expect that an antenna tuner will be recommended (if not required) in order to get excellent matches – especially in a field deployment scenario. My normal source for high-quality antenna wire is The Wire Man in South Carolina – always at the local (and Dayton) hamfests, but also close-by via UPS. His #26 wire is called #534 and is currently $0.16 per foot when purchasing more than 100 feet. The #18 is much less expensive and is listed as #501 at $0.06 per foot when purchasing more than 100 feet. Call it $10 for the wire (overkill) and you have the system for less than $120.

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Primary use of these antennas will be with QRP radios – in particular the Elecraft KX1 and the K2. In the case of the KX1, I’ll be experimenting with high-speed, computer generated CW at 50+ wpm. This would seem to be ideal for ARES work when conditions are horrible since 5w of CW will “punch-thru” abysmal propagation conditions unlike SSB. Of course, the premise is that the receiving station will also be using computer CW decoding. If it works (and it should), it will be faster than 45.5wpm RTTY and have more “punch” than any other digital or voice mode.  When SSB is needed, I’ll either use the Elecraft K2 or one of the K3′s.

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I mounted each of the reels on opposite sides of the LDG balun using velcro to attach the reels to the baluns, since they’re quite light (even with the wire spooled and ready to go), but you could also SuperGlue or Epoxy the reels to the baluns for a more permanent attachment.The wire will come out of each reel and be tied to one of the respective binding posts – after all the measurements are made. In the case of the #26 wire, I anticipate stripping the insulation at the appropriate points for each amateur band – making it easy to field deploy without having to measure the length of the wire. When using the #18 wire, I’ll crimp a conductive ferrule on the wire at each of the band lengths to signify 6m, 10m, 12m, 15m, 17m, 20m, 30m, 40m, 60m and 80m. In the case of the OCFD, only 1 marking is needed for each side of the dipole, so a single ferrule on each side  should suffice.

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The tension on the reels can be adjusted with a knob on the back of the reels – I normally make a very loose when deploying the wire, then tighten it afterward to avoid the spool from running free – even though the wire will already have been secured to the respective binding post. Retrieval of the wire is very simple since the gear radio of the winder is quite high (and it’s absolutely silent in operation).

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Finally – add a couple of Cable Ties to be able to hang the contraption by the balun (binding-posts facing UP) and we’re ready to deploy.

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So here is the finished product.. First, the Straight Dipole (Symmetrical using a 1:1 balun)

Then the unit intended for all-band operation using an OCFD configuration, which requires a 4:1 balun:

 

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In a future article, we’ll actually deploy this contraption and show you the SWR curves, as well as the VSWR bandwidth difference using different gauge of wire. Should be interesting.

 

Pneumatic Antenna Launcher – PADS

Nov 21

Posted by mikelee in Antennas, Feedlines and Duplexers | 1 Comment

PADS – Pneumatic Antenna Deployment System

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I obtained this contraption a few years ago – and have always been impressed with it’s performance. This unit will launch a tennis ball with an attached nylon line over 150 feet into the air, to serve as the leader line for wire antenna installation. What’s unique is that the tennis ball is easily detachable from the line, so that a mono-filiment line can be attached as the bright green nylon line is recovered – the mono-line helping to pull-up the wire antenna or the kevlar rope leader.

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The launcher uses CO2 to propel the tennis ball – either with 12oz Paint-ball type cylinders (with associated fill-valves), or the more convenient 12-16g CO2 cartridges (single-use) using a bicycle tire inflation unit. Each 16g cartridge is good for a single launch to about 150+ feet – so it’s pretty economical given the $2 cost of a 16g cartridge – especially when compared to the cost of damage done by falling rocks, or crescent wrenches. If using the larger 12oz CO2 cylinders, you can get about 30-35 “shots” for the cost of a fill (about $5) – not bad.. considering that the medical  bills on a falling tool would be much higher  :D

There are many articles on the internet regarding DIY pneumatic antenna launchers – but I must admit that I bought mine fully assembled and already in the Pelican case (ok, ok – I know that I’m the ultimate in lazy, but I’m also a mechanical klutz). Tools like this are meant to be shared – not left in storage, so if you’re local and in need to launch some wire antennas, give us a call…

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(left): PADS in Pelican 1500 Case                                  (right): CO2 bottles 20oz each

(left): portable inflator for 16gm CO2 cartridges

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Launcher alone

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Close-up of the CO2 system

SO2R Controller – MicroHam MK2R+

Oct 5

Posted by mikelee in Antennas, Feedlines and Duplexers, HF Antennas and Operation, NET Operations | No Comments

This is a VERY cool device..!! Any of you looking to do SO2R, or to just have a single interface capable of handling two radios should consider this device.

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As mentioned in the SO2R blog entry a few days ago, this unit, commonly called the MK2R+ contains two Sound Cards, and all the audio and switching infrastructure to handle two radios while also receiving and relaying radio data (frequency, mode, etc) to the computer for the logging program. The magic of all this is that the MK2R+ uses a SINGLE USB PORT to your computer, so you don’t have to fiddle with 2 external sound cards, plus numerous USB-to-Serial adapters in order to talk with each of the radios, the rotator, antenna switches, etc…   Everything is contained in a single box – plus the MK2R+ also talks (seamlessly) to the MicroHam Station Master, as well as the Station Master Deluxe which will be released soon.

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Okay – many top SO2R operators use this device to handle the route audio and switching chores for their contest stations – granted. But I’m going to use it for routine, day-to-day operating as well as contesting. The Big-Guns often have 2 radios, but as many as 10 antennas, constantly (auto) switching antennas between the two radios, as well as bandpass-filter and various other gadgets. My set-up is much simpler – as are most of the folks out there who might join an occasional contest, so I will mostly use the audio switching functions of the MK2R+ as well as the built-in sound-cards for CW, RTTY and PSK.

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Set-up of the MK2R+ is very easy – well, sort of.. The hardware set-up is made simple due to the fact that two pre-built radio cables come WITH the unit. You select the radios that you want to interface – and cables are available for almost all of the major brands and models. In my case, we specified a cable for each of the Elecraft K2 and K3 – with specific connectors for the Rear Panel of the K3, so that all the cables would be out-of-the way and not facing the operator. The cable sets are beautifully constructed – very professional and each cable is labeled as to function and corresponding connection point on the respective radio – simplicity itself.

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The software setup is a bit more complex – and more time consuming. It’s worth-while to read the manual TWICE even before receiving the hardware – and again with the hardware connected. There is a piece of software call the uRouter (microRouter) that is the brains connecting the single USB interface to all of the functions contained in the MK2R+, as it emulates all of the serial ports that would otherwise be connected to a computer – such as 2 serial ports for the two radios, 2 serial ports for the radio CW keying lines, etc.. on last count, the uRouter software was emulating over 9 serial ports into the USB connection and doing a flawless job of it (on top of talking to both of the MK2R+ sound card interfaces). This is a very complex piece of software, but it simplifies SO2R by an order of magnitude or more – not to speak of making a VERY CLEAN looking station (no wires all over the place).

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Computer software that takes advantage of SO2R and the MK2R+ specifically includes all of the popular contest software like N1MM, TR, WriteLog, CT and NA amongst others. I’m only starting to get familiar with the WriteLog piece, but initial impression is that it’s very slick indeed..!!

Cost for the MK2R+ is right at $995(price increase in the last 30 days) and it ships from the US Distributor direction in Geneva, Florida. Two radio cable sets are included and extras are $75 for any model radio. Sure, the set-up sounds steep, but when you consider that it includes 2 sound cards ($99 each for the SignaLink), 2 cable sets ($75 each), no need for 2 USB-to-Serial adapters ($35 each), you’ve saved $450 in other costs right there, so that makes the MK2R+ about $550 for the audio switching capability and other essentials to make SO2R work seamlessly.. pretty effective given that it cleans-up the radio table of all the separate units, wall warts, cables and miscellaneous “junk”….   I’m sold..!!

DeoxIT – Amazing Stuff

Sep 24

Posted by mikelee in Antennas, Feedlines and Duplexers, Kit Construction, Tools | 2 Comments


I have a list of about 15 websites that I scan thru each morning regarding technology and ham radio – among them is the Elecraft K3 reflector postings (daily digest). Each of these sources provides me with some valuable – and in some cases, invaluable – information. There is nothing better than to learn from other’s mistakes as well as successes, to try not to repeater their mistakes when learning something new, or to improve upon something already being done but that can be done better.

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Recently, one of the email threads talked about a contact enhancer called DeoxIT – meant to remove oxidation that inevitably begins to accumulate over time, depending on weather and other environmental conditions. Of course, I had to try it and WOW.. this stuff is GREAT. It ranks up there with Kroil and SiliKroil, which I buy by the case from Kano Labs. DeoxIT now becomes part of my permanent list of tools, much like the Hakko 808 desoldering gun and my PowerPole crimper tools – awesome..!!

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I purchased the 25ml bottle (with a dropper-tip) and it’s rated for 1,250 drops (+/-). DeoxIT is made by Caig Laboratories – and the product number of the unit that I purchased is “D100L-25c (ml)”. Cost is $29.95 + $9.50 shipping – a bit steep on the shipping side, but if you only have to buy one unit for the next 10 years, its shipping becomes a bit more tolerable.

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http://store.caig.com/s.nl/it.A/id.1703/.f?sc=2&category=188

 

N6BT – “Array of Light” Book Review

Sep 20

Posted by mikelee in Antennas, Feedlines and Duplexers, ARES Training, HF Antennas and Operation | 3 Comments

I had the pleasure of meeting Tom Schiller (N6BT) last weekend at the Torrance Hamfest. Tom is the co-founder of Force-12 Antenna Company (along with his dad) before selling it after many years to a Texas company. Tom now has a new line of antennas under the company N6BT.COM that appear to be outstanding, yet economical at the same time. I’ll be reviewing some of his designs in the next few months, but in the meantime, I purchased his latest book called “Array of Light” – Straight talk about antennas and related subjects.

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Now what makes Tom unique, is that he doesn’t live in the theoretical world – he’s a a master antenna designer, having designed some of the most successful antennas for the commercial, amateur as well as military market. Although he uses computer modeling, Tom actually constructs and measures antennas of his own design and has been tweaking designs for over 25 years. His designs are in use all over the world and he has a very large following of DX chasers.

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I spent about 45 minutes talking with Tom, since I was curious about his antennas, as well as his latest book. I have to tell you, the book is almost an inch thick in a spiral binding and is LOADED with great information. Now I’m no antenna expert, but I’m also not a complete idiot either  - but I have to tell you that his book is FULL of great information.  There are 54 chapters in the book, with subjects ranging from “Efficiency” to troubleshooting antenna problems, to construction techniques. Virtually anything you would ever ask an expert about building, installing, using and maintaining an antenna system is covered in this book.

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Oh  - did I mention that Tom is an avid DXpeditioner..??  Tom and his crew at Team Vertical have many years of foreign travel to exotic places, shlepping all kinds of radios and aluminum for contests – and the team has a number of World Records to their credit – one of them while operating QRP..!!

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I’m not but half-way thru this book – but so far, it’s TOP NOTCH… HIGHLY RECOMMENDED..!!

Antenna and Family Day – 16-April (Saturday)

Apr 10

Posted by mikelee in Antennas, Feedlines and Duplexers, ARES Events, D-Star Users, Go Kits, Work Party | No Comments

We will be having an Antenna and Family Day on Saturday, 16-April at the Favor Dykes State Park. Doug (N4FPS) has graciously reserved the Pavillion, which is about 50 meters from the water, where there is also an elevated walkway from which we can fish and enjoy the water.

We are anticipating a session to learn about antennas, starting with construction and tuning of an Off-Center-Fed-Dipole (OCFD) for 80-10m which should be about 150-feet in length. That antenna will be installed at the Flagler EOC in the following weeks after the replacement coax is installed. After the OCFD, we’ll also experiment with various antennas, including a Buddi-Pole for barefoot portable HF operation, a Lil’Tarheel for 40-6m and a Butternut HF-9V vertical antenna which is rated to 2kw. We’ll do final construction and tuning of all the antennas, then be able to compare performance of each of the antennas.

We’ll have various HF radios available, including an Icom IC-7000, a Yaesu FT-100D, an Icom IC-7200 and others. We might even have an ACOM 1010 linear to provide us with up to 800w of power to bust-up pileups that might be on the bands. There are numerous HF contests running that weekend, so the bands should be busy and allow us to have a good time.

We’ll have the antenna session starting at about 10am and would like to invite entire families for a “Pot Luck” dinner starting at about 6pm onwards (kids of all ages are most welcome). No cost to join – just plan to bring a dish that can be shared.  We’ll plan to be out of the park before dark.

Please come and join us – we’d love to meet family members and just sit and relax in one of the most beautiful parks in the Flagler/St.Johns area.!!

Members of FPCARC and ARES  - please plan to  join us..!!

A GREAT, Online Electronics Resource

Nov 21

Posted by mikelee in Antennas, Feedlines and Duplexers, ARES Training, DSTAR Projects, Test Equipment | 1 Comment

I was searching the internet last night for information regarding coaxial cables and Vp, or Velocity of Propagation – when I ran into this resource which I found to be most useful. It answered the question that I had (or at least, CONFIRMED the answer that was in my head regarding Electrical Wavelength). But then, I started browsing that same site in more detail (left navigation bar) and found it to be a treasure-trove of great information – from beginning theory, to much more advanced topics. In fact, probably not an over-statement to say that it’s the single best source of electronics information that I’ve found to date.

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I thought that I’d share so that it might benefit any of you who might be searching for similar material.
http://www.radio-electronics.com/info/antennas/coax/coax_velocity_factor.php

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Below is an excerpt of one of the pages from the site – used with full credits given.  Enjoy…

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Arrow Antenna seems to be Shipping again..!!

Nov 2

Posted by mikelee in Antennas, Feedlines and Duplexers | No Comments

Woohoo..!!
I’ve always liked these antennas, so after a couple of months off (taking care of his wife, who had a severe heart attack), they’re back to shipping product. I just ordered some replacement antenna mounts and a couple of their Carry Bags (40″ versions) to test-out for the go-kits. If they’re like the bags for the arrow-satellite antennas, they’ll be very good quality – should have them on Monday to be able to report back.

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Feeling confident in ordering from Arrow again – great products, good prices and now great service returns..!! Expect short delays in shipping, but that should be temporary (see the screen shot).

more tk

Arrow Corner Beam – Dual Band

Oct 27

Posted by mikelee in Antennas, Feedlines and Duplexers | 2 Comments

This antenna is no longer manufactured, but you may come into contact with it at a hamfest or other events – the Arrow Antenna’s Corner Beam. I’ve had mine for a number of years and just recently took it out of storage and got it back into operational status.  Assembly takes about an hour (there’s a lot to the antenna) – and it’s a snap to tune-up.

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Eddie and I put it on the test-stand Sunday morning and were able to get it tuned to a VSWR of 1.2:1 on both bands. Some of the significant attributes: forward gain of 7.8dbi, front to back ratio of over 22db and side rejection of approximately 25db.

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This antenna is great for a fixed-link between repeaters or a base station (you see them all the time between a broadcast studio and the remote, high-power transmitter). If you’re able to find one, it’s a worthy antenna to have in your stable.

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Below: Arrow CB148/450 antenna