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Portable DMR Go-Box for your TYT MD-380/390 handheld

in conjunction with an iPhone 6 / 7 as the "Hotspot"


Now that DMR is taking it's place among the newest digital modes, why not take your handheld with you as you travel and not be reliant on your local DMR repeater. With this article, you can construct a travel Go-box that will allow you to stay in touch with your friends back home and around the world! Consisting of a few items obtained from Amazon and easily assembled, you'll be on the air wherever you travel.


After researching many interesting approaches, I settled on the design seen below. It along with my iPhone 6 as a "hotspot" provides excellent communications.



Components I used in the construction are as follows:







Construction is straightforward. Place your components in the case to best serve your needs. There are a lot of different amperage levels and physical sizes for the power packs so select one that will power the router, Shark RF Openspot and even your iPhone. I chose the Rav Power model because of good reviews and I did not need 3 outlets. Once constructed, you'll need to configure the Shark Openspot, TP-Link Router and enable the "hotspot" on your phone. 



.A robust "codeplug" for the 380/390 radios that works well with this system is available here


Once configured and up and running, you'll be surprised as to how well this system works!


Additional information is available at the Shark RF Facebook Page  Shark RF Openspot Facebook Page 


Good luck with your "Go-Box! 


 To make traveling easier I constructed a storage box that holds both my handhelds, charger, antennas and

programming cable. The Pelican 1170 case holds everything in a safe and secure manner.




SPC Transmatch from A.R.R.L Handbook 1984


Here are some pictures of my homebrew SPC antenna tuner that I built in 1991. It was from the 1984 ARRL Handbook and designed by W1FB - Doug DeMaw. See article here. This tuner is built on a stainless chassis with stainless front and rear panels. Parts used in this tuner include: J.W Miller #2150 200pf variable, J.W Miller #2155 dual section 200pf air variable, teflon standoff's for both capacitor's, B&W turns counter, LaPointe 28uh roller inductor, Centralab JV-9033 ceramic switch, 3 Amidon T-200 torroid cores which form the balun transformer, James Millen insulated shaft couplings, Qualitykits 6:1 vernier dials, E.F Johnson feed-thru bushings, SO-239 chassis mount connectors with teflon insulation and stainless hardware.


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Link Coupled Transmatch modeled after a design by W1SE.

Here is another project, a link coupled tuner modeled after a unit built by Lee Aurick W1SE from 1982. See article here  This tuner is housed in a case I found on E-Bay for a very reasonable price. Components include, an E.F Johnson 154-3-1 488pf variable capacitor, a Cardwell 250pf capacitor, 2 Daka-Ware dials, a B&W 2406T inductor and a 3 position ceramic rotary switch, all which were located and purchased on E-Bay. The coax connector and the ceramic feed-thru's were in the junkbox. The components are mounted on a 18 gauge stainless steel chassis with stainless hardware. Fortunately I have access to a machine shop which simplifies the building process. I finished the case with Krylon spray and it has been clear coated. Built in 2002 but not yet completed in these pictures. Only $80 invested in this project!


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My version of the "Ugly Balun"


Faced with the option to build or buy, I decided to go the build route and constructed a coaxial choke balun to replace a very tired Hy-Gain BN-86 ferrite balun that had been in use on my TH3MK2 tribander for over 25 years. Searching the web, it was easy to find articles relating to all sorts of balun’s and one particular style caught my eye. http://www.hamuniverse.com/balun.html

After viewing the many different types of construction, I decided to build one that would suit my needs and not be ugly! A trip to Lowes and a visit to the junk-box yielded everything necessary for my project.

  • 3” Schedule 40 PVC (Lowes or Home Depot)
  • 25’ of RG8X Coax (I used DX Engineering DXE-8X)
  • (2) 3” PVC End Caps (Lowes or Home Depot)
  • (2) Cable Glands https://www.alliedelec.com/search/productdetail.aspx?SKU=70074427
  • (2) Amphenol PL-259’s w/reducers
  • (4) SS #6 Sheet Metal Screws
  • 5/8” Hole Saw
  • 1/4” & 1/8” Twist Drills

Using the basic instructions in the article on Ham Universe, I selected a 8” piece of 3” Schedule 40 PVC for the form. 25 feet of DX Engineering RG8X coax yielded 21 turns on the form (along with some extra for connections) I started by winding the RG8X on the form to give me the width dimension of the first and last coax turns so I could drill the start and finish holes to keep the turns tight. Once that dimension was determined, I drilled the first ¼” hole at a 45 deg. angle in the PVC so not to strain the coax. I fed about one foot of coax thru this hole and started to wind the turns on the form. When I reached 21 turns, I taped the coax to the form to hold it in place and drilled the final ¼” hole for the coax, again at a 45 deg. angle and left an additional foot for connections. If done correctly, the turns should all be tight together (as shown below)



Take the 2 flat end caps and find the centers of each and using a 5/8” hole saw make the holes for the cable glands. Mount the 2 cable glands (be sure to order the locknuts which are sold separately) Pass the coax cable from each end of the form thru the glands and position the caps on the PVC form. Tighten the cable glands to hold everything in place then carefully drill two 1/8” holes thru the caps and into the PVC. Fasten each end cap with two 1/2" #6 sheet metal screws.

For my needs, I opted for the connection type shown. Depending on your situation, SO-239’s, binding posts or a direct run of feed line could be used. Other sizes of coax (RG8, RG213 etc) can be used when building these balun’s. Just follow the basic instructions on the Ham Universe webpage.

If you need a decent 50-ohm choke balun for use on a tribander or other type antenna needing a choke balun, this simple project like this could be for you. My project got recognition on the Ham Universe “Ugly Balun” webpage!


High-Sierra HS-1500 rebuild and assembly of a High-Sierra "Wilderness" clone

I have enjoyed working with these fine screwdriver antennas. Over time, I have owned three of them. Two I still have. The first was purchased used on e-bay complete with whip and controller. I used that one mobile with a IC-706MKIIG for a few years and then decided to turn it int a clone of the High-Sierra "Wilderness" antenna package. One design flaw that I found with these antennas was use of dissimilar metals at the base of the antenna. A large brass plug is inserted into the 2" aluminum tube that protects the coil and over time, galvanic action takes place and you must disassemble the antenna and clean the parts and reassemble using De-Oxit or other conducting grease. I researched using Stainless Steel tubing to replace the aluminum and found that it would be an easy remedy to this problem.

I was able to find a nice 4' section on 2" SS tubing and had to modify the coil form slightly to fit into the tube since the ID was slightly less in diameter than the stock tube. A trip to my friendly machine shop and we chucked up the coil form in the lathe and removed the .020" needed to make the form fit loosely in the SS tube. At that time, I also replaced the original motor with the new style BlackHawk motor that are being used on the 1800 version models.

Below are some pics of the completed project along with a pdf file of the assembly instructions. These upgrades took a fine antenna and made it bullet-proof. It makee a fine portable or Field Day antenna and can be returned to mobile operation at any time.

Foolishly, I ended up selling the package to move on to another project. As fate would have it, in 2011, I was in need of another HS-1500 to use as a home base antenna at our condo in Florida. Looking on QTH.com yielded two more HS-1500's One was quickly rebuilt and put into service. The other is used as a spare. The antenna in Florida can be seen at the bottom of my timeline page (1965 - 2013)


The completed antenna with radials and
Diamond SBB-5 vhf/uhf whip

Testing with radials prior to upgrading


PDF file of the assembly instructions are FieldDaySetup - Shows close-ups of the antenna and mounting fixtures

Upgrade of a Heathkit SA-2550


Complete rebuild of the motor driven capacitor and housing along with the construction of a new power supply/controller. This controller is not powered by the original walwart but by a transformer buillt into the enclosure. This unit will be the heart of the shunt feed for my tower on 160 meters. It may require some additional capacitance to be added to the 500pf capacitor to be able to achieve a match at 160 meters. Currently I am using another SA-2550 as a matching capacitor at the base of my 160 meter inverted-L.

Heathkit SA-2550 remote variable capacitor

Homebrew controller to replace wallwart


Heathkit controller used with a walwart

My controller - heavy duty supply


W2FMI "Constant Impedance" Vertical Antenna


I built this antenna from an article by Jerry Sevick W2FMI. Basically it's an extended length vertical that is tuned with a 100pf doorknob cap. It uses Hy-Gain 14AVQ traps, Hustler base section and new aluminum tubing from DX Engineering. I had it mounted above a DX Engineering radial plate with (60) 40' radials. Because of the design, bandwidths were increased on each of the bands and matching was improved. It worked as designed and after initial setup, no more adjustments were needed. SWR was below 2:1 across 40, 20 & 15 and in my area of interest on 10 meters. I had planned to use the Heath SA-2550 above for more critcal tuning but it was deemed overkill. I sold it in April of 2016 to fund another antenna project (K4KIO HexBeam)



160 meter shielded receiving loop project

In the test fixture prior to resonating

Construction data here


Resonating trimmer capacitor and matching network













Five-position homebrew remote antenna switch


I built this switch about 10 years ago from an article in QST. It used five P&B high power relays mounted on a Plexiglas panel and installed in a Hammomd fiberglas enclosure. I wired it to work with a Heathkit SA-1480 controller. Worked well and handled high power. All antennas but the one in use were grounded so it was a very quiet switch. I used it for a few years but was sold to make room for a different switching arrangement.


KO4NR Remote Antenna Selection Switch





Here is the beginning of my KO4NR Remote Antenna Switch. Construction data here Got all the parts mounted to the remote and power supply boards and have tested for operation. Need to mount the PS board into the Ten-Tec enclosure (shown) and find a suitable weatherproof enclosure for the remote board. This switch uses 8-conductor cable for operation.


Found a nice weatherproof box from Hammond for this project. Model# 1590ZGRP162
Installed seven Altech cable glands for the coax feeds. (Sold in March 2013)


Antenna/Rig Selection Panel

Built this panel out of need to switch radio's and antennas. Used 2 Daiwa CS-201 two-way

switches and a Heathkit HD-1234 5-way rotary switch. Built on a 18ga. SS panel

Below is the layout I used with panel to select between two rigs, tuner operation and two meter operation.

The output line on the panel connected to my Heathkit SA-1480 remote antenna switch yielding 5 antennas.


Station Layout @ WB2RCB