EMCOMM Portable Station
This is a page designed to help the
EMCOMM operator thinking of "going portable". It will describe a way of
having VHF / UHF / HF / voice and digital in one "box".
The first thing I want to say it, get at least your General class
license and become an HF operator. You are limited having only a
Technician license in what you can do, and HF operation requires
knowledge and skills learned. Also, don't build a "portable" station
and only use it portable during EMCOMM. You WILL meet Mr. Murphy and
his laws head on! Get the station out and use it to make sure you know
how to operate it, and can work out bugs.
The first piece of equipment we will look at is radios. Preferably HF
radios. What do we want? Well here is my checklist:
1. 10-160M operation, capable of MARS if needed and you are a member
2. Auto antenna tuner included, but manual tuner is OK.
3. Digital ready. (More in this shortly)
4. 100 watt output
You need a radio capable of operating all HF bands, with an auto tuner
on board (or an external one), 100 watt output, and digital ready. Some
suggestions are the Yaesu FT-450AT, Kenwood TX480SAT, Yaesu
FT-857, or Icom IC706MKIIG. The last two have HF / VHF /
UHF capability, but do not have auto tuners. Auto tuners are OK, but
also have available a good
quality manual tuner just in case. All the HF radios mentioned have
good filtration settings on RX, which is a plus in noisy band
What is "digital ready"? All modern HF rigs can operate digital. But
some are better than others. The #1 thing to look for is a 6-pin mini
din jack on the back, that follows the "packet standard" folks have
tried to do. Here is what that is:
This same jack is also found on newer VHF and VHF / UHF rigs, seen
If you notice that jack looks a lot like a PS/2 computer mouse or
keyboard plug, and that is because that is exactly what it is. But, a
word of warning, mouse and keyboard cable won't work to build TNC or
sound card cables, because they only have 4 wires, and one of the wires
is in the wrong place! Either purchase a cable from the manufacturer,
use a keyboard / mouse extension (male to female) cable. Some other
radio accessory suppliers also carry parts or premade cables.
Both pictures show a TNC connected, BUT the same jack will work for
sound card modes. You might even devise a way to switch between sound
card and tnc hookup. (See the http://www.qsl.net/na4it/interfaceswitch/interfaceswitch.html
for ideas in using an old comport switch.)
With all that said, what do we look for in a VHF / UHF rig? Well, some
HF rigs come with VHF / UHF capability. But, ask yourself a
question...Do you need to monitor HF and VHF / UHF at the same time? If
so, plan to get a VHF / UHF radio. And here is what to look for...
1. VHF / UHF capability
2. Dual watch (not a necessity, but is nice)
3. Digital Ready (see all the above...)
Some particulars about VHF / UHF when it comes to digital...the Kenwood
APRS ready radios are nice, and do a good job on APRS. But, the TNC is
not usable for digital EMCOMM work. I recommend instead a dual band
radio such as the Yaesu FT-8800R, FT-7800R, or even if you need VHF
only, the Alinco DR-135 (without the TNC).
OK, now that we know what we want in radios, what else do we need. Here
is a list:
20- 35 amp Power Supply (maybe not included in the "box" but in the
vehicle if needed and AC power is available)
A good battery. Suggestion, used or take out computer UPS batteries are
sometime available at battery stores. Look for a 100 amp hour or
greater. It will be heavy, so think of how you want to move it...a hand
truck maybe? Not a bad idea...
Sound Card interface...yea I know (I don't care anything about
operating digital...!) Well, if you plan to be in EMCOMM, get used to
it. Besides, it's a lot of fun when the chips aren't down and you are
just enjoying the hobby. Either build it yourself, or might look at the
Signalink USB (but word of warning, keep the USB driver disc in your go
kit, along with a copy of your digital software, in case your computer
bites the dust and you have to use someone elses).
TNC... if you plan on being able to do Winlink, you WILL need a TNC
that is capable of at least Pactor I. If you have money laying around,
then buy the SCS Pactor I, II, III modem. Other than that, look for an
AEA or Timewave PK232MBX or Kantronics Pactor I capable modem with the
very latest firmware.
Other stuff... well, a lot of guys add a lot of neat looking switches
and meters. BUT...these things eat power! Sans the pretty stuff and use
your VOM to see what your voltage is. Be sure to fuse every positive
negative lead at the equipment specs, and fuse your main power supply
wires going to the battery of power supply at 30 amps. Power poles are
OK, but since you are building your box for your use, you probably only
need them on the power supply wires. I would suggest you make a
powerpole to ring terminal adapter for the end of it...maybe even a
powerpole to battery clip adapter also.
Laptop...I would suggest at least Windoze XP with all service packs,
1.8 GHZ processor, and 1GB of memory. As I have said before, keep
copies of all software on disc or thumb drive. Keep the laptop in a
laptop case, separate from the rack case, and make sure you provide in
the rack case for power, serial, and / or USB hookup for the laptop.
Might think about a small inverter to power the laptop, if you can't
get a 12V cable for it. (most laptops pull no more than 90
watts...don't buy a huge inverter... it will kill your battery).
OK..the "box". First, you need to figure out how bug the box needs to
be. We are going to use a "rack case" that is used predominately for
professional sound equipment. A "rack space" is 1 3/4 inches tall x 19
inches wide. So if you by a 12 space rack case (which is HUGE) the
opening will be 19 inches wide x 21 inches tall. Look at places like
Guitarcenter.com (they also
have some local stores), Musciansfriend.com
and other whole sale sound equipment suppliers. BE SURE to buy from
someone who buys lots, so you can save lots! You are going to spend a
little money, but the convenience and protection is well worth it. While
you are at it, pick up a couple of rack shelves to mount
your equipment on. You might also look for a rack drawer to store
paper, pencils, cables, etc.
Most folks can get by with an 8 space case and a couple of shelves.
Remember, you can mount equipment on the top & bottom of the
shelves! Below are sample pictures...
this a 12 space case (19"W x 21"T inside)...
this is a 3 space case (19"W x 5 1/4"T inside)
You will want to look for the cases that have the rack rails only on
the front, they are cheaper (unless you want them
on the back).
this is a 2 space rack shelf (may or may not have mounting holes in
these are rack drawers (make sure they are enclosed...)
OK last but not least...ANTENNAS! Let's look at VHF. A good quality VHF
/ UHF vertical is probably what you want. No too long, but preferably
one piece. Look at MFJ, Diamond, Cushcraft, etc. A good mag mount to
stick on a file cabinet, or on a metal building is a good idea too.
HF antenna...you just can't beat wire. Look for something muilti-banded
or broad banded. I would personally stay away from the "folded"
dipoles, as they are hard to set up. A trapped antenna for 20/40/75
meters, or maybe even the new "Cobra Dipole" is good. The only ladder
line fed 135 ft "Zepp" works too, but you will need a balun for the
radio and tuner, or a tuner equipped for ladder line. And, Hamstick
type antennas put up in a dipole
configuration work well. Here is a hamstick dipole mount...homebrewed
Note, one side DOES need to be an
insulated stud mount!
You need to be able to work 20, 40, 60, and 75M, and if your local
group sees the need, maybe 10M for short range local stuff. Forget
using verticals on HF...period.
Don't forget coax and rope...you is gonna need it! For rope, try to get
a highly fluorescent color so it will be seen, or get some warning tape
to hang on it so people do run into it.
How about supports...well, worry about the center. The 4 foot
fiberglass military masts work great, can be extended by adding more
sections, and is light weight. Build a good metal base that maybe goes
under your vehicle tire, and let the dipole be part of the guys. Put
the VHF / UHF antenna on top with some worm clamps (Home Depot has
these with thumbscrews!) The ends of the dipole can be tied to bumpers,
light poles, trees, street signs, etc etc etc.
If you think it through, you can come up with a great portable station,
that is easy to transport, and quick and easy to set up. Good luck.
Below is a good picture of a finshed "dropkit" or rack case fully
Personal opinion note:
I DO NOT
recommend "agency go kits" of radio equipment. Why you ask? Operating a
kit if this type in an emergency situation requires that the operator
be well trained in the kits operation. Most "agency" kits are built
because they think it is a good idea. They are used maybe one time a
year, and other than that, no one sees it until another "event",
usually a drill or exercise, where an evaluator is watching and scoring
the drill or exercise, which will lead to government money being given
to the agency.
If the kit pitured above were set before you, and you were told to send
a message on WL2K using Pactor III, could you do it? But, if the above
kit was one you owned, and used every day, that capability to operate
the system would change much to the better.