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.
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.
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
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.
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
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
High-Sierra HS-1500 rebuild and
assembly of a High-Sierra "Wilderness"
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
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
Testing with radials prior to
PDF file of the assembly instructions are FieldDaySetup -
Shows close-ups of the antenna and mounting fixtures
Upgrade of a
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
Heathkit SA-2550 remote variable
Homebrew controller to replace
Heathkit controller used with a walwart
My controller - heavy duty
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
KO4NR Remote Antenna
|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