The KØNR Radio Site


VHF QRP: Give it a Try
Bob Witte, KØNR

Mention "QRP operation" and most radio amateurs think of a small CW transceiver for the HF bands. Mention "VHF QRP" and the response may be more like "what's the matter, your transmitter broke?" The surge of interest in QRP is largely focused on the HF bands and most weak-signal operation on the VHF bands is high power, for good reason. Putting together a competitive weak-signal station requires careful attention to every decibel in the system --- receive sensitivity, transmission line loss, antenna gain and, yes, transmitter power. On the other hand, there is something to be learned from the QRP community about having fun with amateur radio.

What is QRP?
QRP is normally defined as operating with 5 Watts of output power or less. If you dig a little deeper, you'll find that low power operation carries a lot more with it.

QRP is generally associated with:
• Compact, portable, battery-powered equipment (often used portable in the outdoors)
• A personal challenge and/or a minimalist approach (get the job done using efficient equipment)
• Emphasis on operator skill (especially CW operation)
• Contesting or other events that promote QRP activity

Are these elements of radio operating relevant to VHF and up?
Our VHF equipment is not always compact and portable but in recent years there has been a significant reduction in the size and weight of VHF and up equipment. It started with the combination HF/VHF/UHF mobile rigs from ICOM (IC-706) and Yaesu (FT-100). For QRP enthusiasts, the FT-817 from Yaesu is a backpack-ready 5 Watt rig that spans HF through 70 cm. (Unfortunately, none of these rigs include the 222 MHz band.) Now that I think of it, we should include the older single-band all-mode rigs such as the FT-290R and the IC-502. More importantly, we see hams using these rigs for VHF/UHF mountaintop and grid expeditions. So, yes, there is a match between compact, portable operation and VHF and up.

With regard to taking on a personal challenge in radio operating, the weak-signal VHF/UHF enthusiasts are already there. The higher bands were once thought to be of no use except for limited line-of-site propagation. The weak-signal ham community has proved that idea wrong.

The weak-signal VHF world also puts on emphasis on operator skill, including the use of CW. You must be a fast and efficient radio operator to make contacts when VHF band conditions are marginal or changing rapidly. Most serious VHF operators have had the experience of trying to work a distant station on SSB, then switching over to CW to complete the contact. Whether you like using CW or not, it does get through tough conditions better than phone, so it is important to have in your bag of tricks.

With regard to contests, this is where QRP VHF is formally established. The major VHF contests have a special entry category for QRP operation, with a maximum power level of 10 watts, not 5 watts. The ARRL contests refer to this category as "Single Operator Portable" while the CQ World-Wide VHF contest just calls it "QRP". The intent of these categories is to encourage portable operation, presumably from a rare grid or mountaintop location.

In summary, we can check the box on all of the main QRP elements as applying to VHF and higher.

Intro to VHF QRP
First, let's talk about some of the more popular frequency bands above 50 MHz. I am going to discuss the bands up through 70 cm because they are the most commonly used. Certainly, there is a huge amount of spectrum above 70 cm with lots of potential, especially if you are into experimentation and homebrewing of equipment. Note that I am using the term VHF quite loosely, to mean any band above 50 MHz.

Band

Frequency Range

Calling Frequencies

Comments

6 M

50 to 54 MHz

SSB: 50.125 MHz

FM: 52.525 MHz

Normally local communications but Sporadic-E and F2 propagation are common.

2 M

144 to 148 MHz

SSB: 144.200 MHz

FM: 146.52 MHz

The most popular VHF band, used for local communication via simplex and repeaters. Normally local communications but long distance tropo propagation and Sporadic-E propagation occasionally occurs.

1.25 M

222 to 225 MHz

SSB: 222.100 MHz

FM: 223.5 MHz

Propagation similar to 2M but rarely sporadic-E

70 cm

420 MHz to 450 MHz

SSB: 432.100 MHz

FM: 446.0 MHz

Propagation similar to 2M but no sporadic-E

Note: This table shows the US amateur bands, other countries may have different frequency allocations.

Equipment
There are a number of transceivers available for VHF QRP. One of the most exciting rigs to appear on the scene is the FT-817, which covers HF, 6M, 2M and 70 cm. More recently, ICOM introduced the IC-703, which is primarily an HF QRP rig but is available in a version that includes 6 meters. MFJ offers a couple of single-band transceivers, the MFJ 9406X 6M SSB rig with 7 watts output and the MFJ 9402X 2M SSB rig with 10 watts output.

Elecraft, the well-known manufacturer of radio kits, recently introduced a line of transverters that will allow HF rigs to operate on VHF (see "CQ VHF Reviews the Elecraft K2 Transceiver", CQ VHF, Summer 2003). According to the Elecraft web site, there are three models: XV50 (50 MHz), XV144 (144 MHz) and XV222 (222 MHz) with 20 to 25 watt output.

There are older rigs available on the used market such as the FT-290R series from Yaesu and the IC-202 series from ICOM. These are low power, single-band rigs for 6M, 2M and 70 cm. Check out your local hamfest or online auction such as Ebay (http://www.ebay.com).

Antenna
The antenna for any amateur radio station is a critical component. The key difference at VHF and higher is the shorter wavelength, which means antenna elements are much shorter and perhaps more numerous. The polarization of the antenna is important under most situations, since you want to have your antenna with the same polarization (horizontal or vertical) as the station you are contacting. Most FM-oriented stations use vertical polarization, consistent with easy mobile mounting and simple omni-directional antennas. Serious weak-signal VHFers almost always use SSB or CW and horizontal antennas.

For the 6-meter band, we can adapt many of the standard HF wire antenna designs. For example, the classic half-wave dipole is a good choice, providing an efficient radiator about 9 ½ feet long. A quarter-wave vertical is also a possibility, especially for mobile installations. Antenna polarization is not an issue for long distance propagation via the ionosphere since the polarity tends to change anyway. For local contacts, horizontally-polarized is generally the way to go. Yagi beam antennas for 6 meters are normally mounted horizontal and provide gain over a dipole.

For the 2-meter band, the wavelength and antenna elements are quite short (about 1 meter or 39 inches) compared to the typical HF antenna. Here, the yagi antenna is the most popular, with as few as 3 elements and as many as 17 elements. For CW or SSB work on this band, you'll definitely want to be horizontally polarized. For FM, vertical is more common.

The bands higher than 2 meters tend to also use yagi antennas but with correspondingly shorter elements. The shorter wavelength allows for more antenna gain within the same antenna dimensions. Of course, a directional antenna means that you need a method for pointing the antenna in the desired direction.

Transmission Lines
Transmission line loss is an issue at VHF and higher frequencies. This loss is usually specified in dB per 100 feet of cable length. The losses of some common coaxial transmission lines are shown in the table below. Small cables such as RG-58 have high loss at VHF frequencies, losing 3 dB (half the power) in 100 feet at 50 MHz. However, RG-58 might be acceptable for shorter cable runs, say 25 feet or less. RG-8x is not much larger in diameter but delivers lower loss. For longer runs, the larger "full size" RG-8U and 9913 are necessary to control transmission line loss.

Cable Type

Loss per 100 feet
(50 MHz)

Loss per 100 feet
(150 MHz)

Loss per 100 feet
(450 MHz)

RG-58/U

3.1 dB

6.2 dB

10.6 dB

RG-8x

2.3 dB

4.7 dB

8.6 dB

RG-8U/foam

1.2 dB

2.3 dB

4.7 dB

9913FX

0.9 dB

1.6 dB

2.8 dB

Source: Cable X-perts, Inc. catalog, http://www.cablexperts.com

Operating
The place to start on VHF is to go to the calling frequency and call CQ. Unlike the HF bands, there is a tendency to mix CW and SSB operation on the same frequency space on VHF. For example, on 2 meters you might hear an SSB signal calling CQ on 144.200 MHz then a few minutes later hear a CQ using CW. Someone might even respond to the CW CQ using SSB and take up the QSO on phone. It is good operating practice to move off of the calling frequency once contact is established. However, you'll hear people rag-chewing on the calling frequency, especially in areas that have little VHF activity.

Without a band opening, you are dependent on local activity to make contacts on the VHF bands. Local activity is, well, local and depends on how many VHF operators there are in your area and how often they get on the air. The amount of activity on these bands will vary dramatically from place to place. Some areas have a formal or informal activity night, sometimes by band. For example, Monday night may be the 2-meter activity night, while Tuesdays might be for 1.25 meters. Obviously, this is a good time to get on the air, check out your equipment and work some of the local VHF crowd. Another opportunity is a local VHF net, most common on 2 meters.

Finally, VHF contests are great for concentrating activity and represent a chance to work lots of stations in a short period of time. These weekends are my favorite weekends to operate VHF, not so much to compete in the contest but to enjoy the higher level of activity on the bands.

VHF Contests with QRP Competition

VHF Contest

URL

ARRL January VHF Sweepstakes

http://www.arrl.org/contests/forms

ARRL June VHF QSO Party

http://www.arrl.org/contests/forms

CQ WW VHF Contest (July)

http://www.cq-amateur-radio.com/World Wide VHF Contest.html

ARRL September VHF QSO Party

http://www.arrl.org/contests/forms

Grid Locators
Besides a signal report, a key piece of information that gets exchanged on the VHF bands is the grid locator, which indicates your approximate position on the planet. The Maidenhead Locator System divides the earth into rectangles that are 1 degree latitude by 2 degrees longitude. The VUCC (VHF/UHF Century Club) and other awards are based on the number of grids contacted. When you get on the SSB/CW portion of the VHF bands, the operator on the other end will likely want to know your grid. For example, the grid that covers greater Denver, CO is DM79. For most VHF and UHF operation the four-character grid is used (e.g., DM79), but two more characters can be added to create a more precise 6-character locator (e.g., DM79nc).

The best way to determine your grid is to take an accurate latitude and longitude measurement and convert it. A GPS receiver is a very convenient and accurate way to determine your position and many of them can display the location in the maidenhead grid format (usually 6 characters). Otherwise, you may need to consult a map of your area that shows latitude and longitude. The ARRL web site (http://www.arrl.org/locate/gridinfo.html) has more information on the grid system, including a web page that can calculate the grid locator based on latitude and longitude.

Mountaintop Operating
One of the advantages of QRP operating is that the equipment is small and portable. You can operate from almost anywhere! For VHF, the obvious thing to do is increase your height above average terrain.  In other words, drive or hike to your favorite mountaintop location and activate it. In Colorado, we have an event designed just for this purpose, called the Colorado 14er Event.  VHF contests are excellent opportunity to operate from your local high spot.  If you don't have a mountain close at hand, then check out the local fire tower, lighthouse, grain silo or skyscraper.

Summary
We made a quick tour through some basic operating information for the bands above 50 MHz. This is just a start, so please give me your feedback, ideas and suggestions on future topics.

72, Bob KØNR.

References
ARRL Web site, vhf grid information: http://www.arrl.og/locate/gridinfo.html
Yaesu web site, FT-817 information: http://www.yaesu.com/
ICOM web site, IC-903 information: http://www.icomamerica.com
Elecraft web site, vhf transverters: http://www.elecraft.com/
MFJ Enterprises: vhf transceivers: http://www.mfjenterprises.com/