On the ground with average terrain for two five watt VHF or UHF HTs talking to each other? A mile or two.Originally Posted by Bolt_Overide
On the ground with average terrain for two five watt VHF or UHF HTs talking to each other? A mile or two.
Ken
BBI: ...”you better not forget the safe word because shit's about to get weird”...
revchuck38: ...”mo' ammo is mo' betta' unless you're swimming or on fire.”
This article we used for RACES Basic Operator Training Course is dated, but the fundamental information is still good.
Getting the Most from Your Hand-Held Transceiver
©1998-2009 Arlington County Virginia RACES, Inc., KE4SKY Assistant Radio Officer for Training - Cross-posted by permission.
A portable transceiver with its original flexible helical antenna should not be your primary rig for EmCom.
Many amateurs start with a "handy-talkie" when they get their first amateur radio license. Having learned from my experience in doing so, I recommend that new operators who commute via POV rather than public transportation buy 2-meter or dual-band mobiles as first rigs. Mobile rigs cost a little more than a good brand-name ICOM or Yaesu portable, but are much more useful. For portable operation, carry a compact mobile rig in a briefcase and power it with a 17ah-gel cell battery and telescoping 1/2 wave or ¼-wave magnetic-mount mobile antenna. Include 25 feet or more of RG8-X or LMR240 coax to get the antenna up high, away from people.
This mobile as alternate portable set-up doesn't work for everyone. So, if all you have is an HT, the following will help you to “make the most of it!”
An "HT" does makes good sense:
• For use on solo, foot assignments
• For City dwellers who don't own or regularly drive a car;
• For Commuters who mostly use public transportation;
• For controlling a mobile rig set up as a remote cross-band repeater
• As a “spare,” backup or loaner.
The National Institute of Science and Technology tested Public Safety "high-band" VHF and amateur 2-meter antennas. Flexible antennas commonly used on portable transceivers have -5db, “negative gain” compared to a quarter wave whip held at face level. This means that a 5-watt portable VHF with flexible helical antenna has an effective radiated power of only 1-watt. Carrying a portable on your belt produces -20dB of attenuation, reducing EIRP to 50 milliwatts! UHF results are quite similar.
Flexible "rubber ducky" antennas are rubber covered helical springs, intended to withstand rough handling, but they are not indestructible. Flexible antennas used for a full season on California fire lines for several weeks showed a 60% failure rate. Flexible antennas should be replaced as soon as they show ANY apparent kinks, cracks, abrasion or other wear to visual inspection. For EmCom you should always carry a spare antenna of some type.
An expedient which improves the performance of a flexible antenna is a counterpoise wire (19" long for 2-meters, 11” for 222 MHz or 6.5" for 70 cm or 6” for GMRS) of AWG14 stranded wire, crimped and soldered to a battery clip. Attach the battery clip to the shield of a BNC connector, or use a ring terminal which will fit over the threaded female fitting of an SMA connector, enabling you to install and thread the antenna over it. Reinforce the soldered connection with heat shrink to resist flex.
A counterpoise prevents transmitted RF from coupling with your body. Your antenna now performs like a center-fed dipole, instead of an "end-fed dummy load!" The main lobe of the radiation pattern can be "aimed" by, grasping and pointing the end in the direction where you need a stronger signal.
Some after-market and home-made antennas perform much better than the standard helical "rubber duck." A J-pole antenna constructed of 300-ohm twin-lead rolls up easily and fits into your pocket. When thrown up in a tree, it increases both height and gain. Full-sized, flexible 1/4 wave and telescoping half-wave antennas work very well. A quarter-wave provides unity gain when used with a counterpoise and held at face level. This represents a 5 dB improvement over a short flexible antenna, because most of the effective signal is radiated. If operating from a vehicle, connect your portable rig to a magnetic mount mobile antenna to provide a clear RF path outside the vehicle. This overcomes about -10dB attenuation which results from operating a portable unit from inside a metal vehicle. Always carry suitable adapters so that you can connect your portable transceiver to an outside base or mobile antenna, when one is readily available. Pre-position antennas at shelter sites, etc. for this purpose.
In marginal operating locations a telescoping, half-wave performs better, because it provides the same unity gain without a ground plane that a 1/4 wave antenna does when used with a ground plane. A half-wave antenna can be pulled up into a tree, dangled out a window, attached to a window pane with suction cups, or be used bicycle or motorcycle mobile, or in city driving on a window clip mount. A telescoping half-wave increases useable simplex range of a typical 5 watt, 2-meter portable in average suburban ground clutter from about a mile with the stock flexible antenna to 3 miles or more, depending upon your height relative to the terrain. Adding a counterpoise to a unity gain antenna enables a portable unit to keep in reliable contact within 5 miles of an EOC or base station equipped with a gain antenna on a tower.
Telescoping antennas are more fragile and work best when stationary or in the open. Avoid side impacts, rough handling or prolonged mobile use of telescoping antennas on window clip mounts at highway speed, because excessive flexing loosens their internal electrical connections. Never collapse a telescoping antenna by whacking it down with the palm of your hand. Gently pull it down with your fingers. If you note any wobbling or looseness in the sections, replace the antenna.
Flexible antennas are safer when working in close quarters around people and are more durable when walking through dense vegetation for wildfire suppression, CERT or urban search and rescue operations. They better for dual-band transceivers because telescoping antennas are usually mono-band. Most dual-band flexible antennas approximate a 1/4 wave on 2 meters and a 5/8 wave on 70 cm, are optimized for one band and may resonate poorly on the other. How efficient a particular antenna is can be determined only by testing. A telescoping half-wave, or dual-band-mobile antenna with magnetic mount, which will work either with or without a ground plane, offers the best “bang for the buck.”
Any emergency antenna for your HT should be rated to handle up to 25 watts of RF output. This enables it to be used as an expedient antenna to use with your mobile radio when used in portable operation, or to permit using an external "brick" amplifier such as a Mirage BD35 connected to your portable.
A magnetic mount works best on a car, but an improvised ground plane can almost always be found around the home or office, such as a metal filing cabinet, metal trash can, cookie sheet, rain gutter, refrigerator, window air conditioning unit, balcony railing or any other large metal object. On boats, motorcycles, fiberglass truck caps or wooden balcony railings use a half-wave antenna, which does not require a ground plane. If you need to place an antenna on a bus or other vehicle where a mag mount won’t work, use a suction cup mount: see http://www.w5fc.org/pse_docs/KNOWLEDGE/qst_p56.pdf
A common error of new operators is failure to carry enough battery power to last through a full 12-hour operational period. As a minimum always carry at least one spare charged NiCd pack and a AA battery case with fresh batteries plus a set opf spares, to enable you to keep operating when the power goes off, if you can't recharge your NiCd pack.
Cycle and recharge dry battery packs monthly. Write the recharge date on a strip of tape on each pack. In cold weather keep NiCd packs warm by keeping them in an inside coat pocket and not exposed on your belt. Do not store NiMh packs in your vehicle above 120 degs. F if you expect them to hold charge more than a few hours.
An adapter cord to power your transceiver from an auto cigarette lighter plug or a gel cell battery is essential needed for extended operation. Cigarette lighter cords are often unreliable because auto sockets aren't the best conductors, due to contamination and size variations, which cause the plug to vibrate loose. As an alternate power source, you should still have one, because they are ubiquitous and in a pitch, much better than nothing!
Commercially available portable power packs are expensive and don't provide the best capacity or life cycle. Encourage your operators to make their own using 12-volt gel cell (SLA) batteries such as those used to power emergency lighting, fire alarm systems, medical instruments and computer backup power supplies. These commonly are sized from 7-17 ah and are replaced by hospital and building maintenance on a fixed schedule, commonly every four years, before the batteries are likely to fail from age. SLA batteries require disposal as hazardous waste unless recycled or reused. A donation to your EmCom unit for reuse and recycling reduces their disposal cost. Commercial battery distributors or municipal recycling programs can often assist your unit on proper recycling or disposal once the batteries reach the end of their useful life. Contact your local hospital environmental officer to develop a battery reuse program to support auxiliary EmCom in your community.
Donated SLA batteries must be inspected, recharged and load-tested. A 12V battery with open circuit voltage (Voc ) of 12.8V or more can be tested immediately and distributed for reissue, if OK. Batteries with Voc <12.8V are connected in parallel across a regulated 13.8V power supply. Those which do not accept charge after 4 hours are discarded. Total charge time and current should not exceed 140% of battery capacity.
Recharging voltage for 12V gel cells should never exceed 14V due to outgassing. Reject batteries if their internal resistance exceeds an ohm. This is determined by voltage drop divided by the current load in amps. “Good” batteries suitable for re-issue should not drop below 11.5V under a test load approximating “C,” their full amp-hour capacity, for 30 secs. or “C/5” for one minute.
A simple test load for small gel cells up to 20ah is a 50w, 12V-marine/RV bulb or automotive droplight. This equals about 3.8A, approximating a mobile radio on low power 5w transmit or a portable 2-meter hand held, plus laptop PC and packet TNC. Use two 12V marine bulbs in a Y adapter to simulate a mobile or brick amp at 25w RF output. This is a simple test load for batteries up to a Group U1 (30 ah). In a “good” battery voltage drop stabilizes quickly, does not fall below 11.5V under load and recovers quickly when the test load is removed.
If all you have is a portable transceiver, the above information will help to ensure that you can provide an adequate signal for reliable emergency communications. Doing so is vitally necessary to enable your volunteer disaster unit to complete its mission efficiently and safely.
More information on emergency communications is available on our web site at http://www.w4ava.org
Last edited by Outpost75; 08-18-2021 at 05:27 PM.
^^^ good info right here.
A few friends have been known to set up tactical (“suitcase”) repeaters for events such as Dayton or Knob Creek, but that’s not really practical for emcom.
Ken
BBI: ...”you better not forget the safe word because shit's about to get weird”...
revchuck38: ...”mo' ammo is mo' betta' unless you're swimming or on fire.”
wanted to thank everyone for all the information.
As much as I would personally like to get a higher end radio, it looks like we have settled on the Baofeng. I was wondering if anyone could recommend a model from personal experience?
Friends don’t let friends use Baofengs. What is your budget per radio?
Ken
BBI: ...”you better not forget the safe word because shit's about to get weird”...
revchuck38: ...”mo' ammo is mo' betta' unless you're swimming or on fire.”
+1 to no Baofengs. The only good thing about them is they're cheap. One can get good used Japanese radios for nearly the same price (I paid $50 for my Icom IC-V8, a far superior radio).
Outpost75's post is spot on, but rather than SLA batteries, I'd use Lifepo4 batteries. They're smaller and lighter, and have better discharge curves. They're safer than other lithium technologies. Bioenno makes a good one and are "ham friendly" (I think the owners are amateurs radio operators as well).
You might also read the articles over at https://www.k0nr.com/wordpress/. Bob Witte, K0NR, is a ham heavily involved on Summits On The Air, and does a lot of VHF/UHF work using handhelds. There is a lot of crossover between SOTA, Emcomm, and backcountry comms, so you should be able to glean some nuggets of wisdom there as well.
@Outpost75, are you participating in the upcoming VHF contest? A buddy and I will be backpacking to High Knob just north of Harrisonburg to activate that summit for SOTA and to camp overnight while working the contest. We're only running 5w (him on an HT and an 818, me on a couple of HTs). We'll be covering 6m, 2m, 220mhz, and 70cm. I'm limited to FM via the HTs (all bands listed), but he'll be on FM, SSB, and CW. At that elevation, we should be able to reach your neck of the woods.
Chris
I'm a fan of Baofeng's but, my use case is limited to Tx-ing through nearby repeaters in a mostly suburban environment. If my distances were longer or I needed top-reliable point to point communication, I'd likely make a different choice. I have a 50W Yaesu built into a pelican case (set up to run on battery, cig lighter and 110v) for such occasions.
Amazon is a good source for Baofeng's, just be sure to buy from the Baofeng Amazon store or you risk counterfeits. For sure not less than a 5W model. There are some 8W models out now as well, but, I would not operate those (or even the 5W, honestly) without a remote mic. Putting 8W up to my ear and hitting PTT seems unwise.
"No free man shall ever be debarred the use of arms." - Thomas Jefferson, Virginia Constitution, Draft 1, 1776
@Outpost75, are you participating in the upcoming VHF contest? A buddy and I will be backpacking to High Knob just north of Harrisonburg to activate that summit for SOTA and to camp overnight while working the contest. We're only running 5w (him on an HT and an 818, me on a couple of HTs). We'll be covering 6m, 2m, 220mhz, and 70cm. I'm limited to FM via the HTs (all bands listed), but he'll be on FM, SSB, and CW. At that elevation, we should be able to reach your neck of the woods.
Chris[/QUOTE]
PM me with date and time and maybe we can set up a sked. Normally I don't do contests, but have both FM and SSB on 2 meters and it would be fun.
@Bolt_Overide, here are two easy button radios that are each miles better than any of the inexpensive Chinese brands:
2 meter amateur, it can be “opened up” for outside the amateur band (“MARS mod” http://radioaficion.com/mods/ic-v86-mods/ https://www.hamradio.com/detail.cfm?pid=H0-016666
Unlicensed commercial, lower power but no issues with not all users having an amateur license: https://www.hamradio.com/detail.cfm?pid=H0-017480
If encryption is needed, you can find older used Motorolas but you’d also need to budget for a keyloader. If you want to go that way, in my opinion look for used VHF XTS3000s. Even without encryption, a P25 digital radio like an XTS will just be static to most casual users.
Yet another option is a amateur radio that uses proprietary digital. It can be monitored by anyone with the same maker’s hardware, but most people are too lazy to bother. I personally would not go that way.
Ken
BBI: ...”you better not forget the safe word because shit's about to get weird”...
revchuck38: ...”mo' ammo is mo' betta' unless you're swimming or on fire.”
Budget per radio would preferably be $100 or less, but if I had a compelling argument I could probably get it to $150
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