Stuart/KB1HQS has been experimenting with various modifications of the Arrow II antennas. Recently, he put together a video of the various mods, well done and interesting:

Ultimate Arrow Antenna Modifications

I am a big fan of the Arrow II style antennas for VHF SOTA. Initially, I used the dualband 2m/70cm antenna for satellite work as well as mountaintop activity. This started before SOTA was even a thing, as I hiked in the Colorado mountains and made radio contacts just for fun. These days, we normally carry the 2m-only version of the antenna, with split boom and 3 elements. My personal seamstress (Joyce/K0JJW) worked up a really nice rollup case for it. Sometimes, we’ll take along a separate 5-element 70 cm Yagi, which can remain fully-assembled and strapped onto my pack.

All antennas are a compromise between cost, size, weight, performance, convenience and durability. I have found that the 3-element Yagi from Arrow fits my needs really well. I have not been motivated to modify it. The Arrow antenna has a gain of about 6 dBd and is 37.5 inches long. We handhold the antenna and that is about as big/long as I’d like to hold. I am still in search of a higher-gain antenna for those special situations when I know that a few more dB of gain could make a difference. I’ve not really found anything I like. A longer boom would likely require a mast and, therefore, a guy system, which adds more weight and complexity.

Antennas are a never-ending source of options and experimentation, so go out and try something new.

73 Bob K0NR

The post KB1HQS Arrow Antenna Mods appeared first on The KØNR Radio Site.

Closing out 2021, here are the top five blog posts at k0nr.com during the year. Some people may see this as a lazy way of creating one more blog post for the year without much work. This is definitely true. I hope you enjoy it anyway.

Leading the list is this blog post…a perennial favorite that seems to make the top five each year:

Getting Started on 2m SSB

This is another popular article that explains some of the details behind the 2-meter band plan. This particular article is tuned for Colorado but it also provides a link to an article that covers the topic for the USA.

Choose Your 2m Frequency Wisely

New this year, is the post about the North America Adventure Frequency, which was promoted by the ARRL Contest Update newsletter:

North America Adventure Frequency: 146.58 MHz

This post is my attempt at humor concerning the SOTA obsession of small transceivers:

The Truth About Tiny SOTA Transceivers

Once again, coming in at fifth place is one of my personal favorites that talks about proper kerchunking of repeaters. It even introduced a new Q-signal for kerchunking, although I must admit it may not be catching on.

Proper Kerchunking

Editors Choice

Just for good measure, I am including one more post that I think is notable. I wrote this one after looking around the web for a good explanation of what is a valid QSO? I never did find a good, up-to-date definition of a QSO, so I wrote one. This one may turn out to be an evergreen article but so far it has not gotten a lot of hits.

What Is a Valid QSO?

Merry Christmas and Happy New Year!

73 Bob K0NR

The post Top Five K0NR Blog Posts for 2021 appeared first on The KØNR Radio Site.

I’ve been interested in the idea of a microphone-centric radio and wrote about it here: How About a Mic-Centric Mobile Transceiver? Shortly thereafter, I discovered that QYT has introduced a VHF/UHF ham rig that has the display and controls in the microphone (Model KT-WP12).

You may want to watch the video by Tech Minds, which does a good job of introducing the radio.

I was very keen on trying this radio out, so I purchased one, paying about $110.

On the Bench

First, I did some bench tests to check the basic performance of the radio. The receiver sensitivity, transmit frequency and FM deviation all looked very good. The one specification that was disappointing was the RF power output. On the 2m band, the output power was 20.6 W, while the 70cm band was 15 W. The specification for the radio is 25 W. The power was measured using an HP 8920A RF Communications Test

I’ve noticed this on other radios from Chinese manufacturers: the basic specs of the radio check out, except the RF power level is low.

User Interface

As you might expect, cramming all of the controls into the microphone is a challenging user interface design. I spend quite a bit of time playing with the radio at home before actually using it on the air. Overall, I found the user interface to be acceptable, but several areas that should be improved.

QYT relies on the menu system to provide control of many of the settings. This is similar to the various Chinese handhelds where you push the MENU button to access the menus, followed by UP/DOWN to sequence through the menus, followed by MENU to access the specific setting. Then the UP/DOWN buttons choose the value of the setting and another push on MENU to accept it. The volume control setting is buried in this menu system, which seems like a poor choice. Fortunately, Mick/M0VMK pointed out that the volume can also be set by enabling the monitor feature (big button on the top of the mic) and hitting UP/DOWN.

This design depends too much on the menu system. A few user-defined buttons would be a real help. This radio could benefit from a serious redesign using User-Centered Design.

This radio has one receiver but allows for three independent frequencies to be displayed simultaneously. There is a scanning mode that tries to emulate a multi-receiver radio. This too is all too common with the Chinese radios…somehow they have it in their heads that this adds value for the user. My experience is that it mostly confuses the user. Most users would be better served with a single frequency display, supplemented with dual-watch and scanning capability.

You probably won’t be surprised that the user manual is terrible, also common with Chinese manufacturers, but this one is particularly bad. Same with the programming software…it mostly works (I had a few crashes) but it is poorly written.

On The Air (SOTA)

I was very interested in trying out this radio for Summits On The Air (SOTA) use. The idea is that the radio can be stuffed into a fanny pack, with the microphone, speaker, display, and controls in your hand.

The basic concept of holding everything in the palm of my hand worked out quite well. The display was visible in bright sunlight, the speaker audio was clear, and the microphone worked great. I made a number of SOTA contacts and received good signal reports. I held the microphone in one hand and pointed the 3-element Yagi antenna with the other hand. (Joyce/K0JJW assisted with logging and we took turns working the SOTA chasers.)

As soon as I fired up the radio, I heard interference on the 2m band, not very strong but noticable. It sounded like it was coming from an FM broadcast station. Pointing the Yagi antenna in the direction of the FM station on the adjacent mountain seemed to confirm the source. I did not hear any interference on the 70cm band. I’ve operated from this SOTA summit before and have not noticed any interference with other equipment, including Yaesu handhelds. Also, I switched to my Yaesu FT-90 and the broadcast station was not heard. As various people have suspected, this indicates that the receiver in the QYT is not very robust in terms of rejecting off-channel signals. Of course, this is an anecdotal report, not based on bench measurements.

I also encountered an anomaly where after my transmission, the radio did not revert back to receive quickly. There was a few seconds where no audio was coming out of the transceiver. This caused me to miss a few responses to my CQ call. This issue requires some additional investigation. It may have just been operator error on my part. However, I suspect that the radio was probably locking onto another frequency but I am not sure (see previous comments about the three frequency scanning mode). So file this issue under “stay tuned for more information.”

Note that I did not use the radio very much on repeaters, focusing on SOTA simplex operating with no transmit offset or CTCSS.

Conclusion

On the positive side, I really like the microphone-centric approach that this radio uses. The user interface can be improved but it is good enough.

The two big limitations of this radio are 1) low RF power output and 2) weak off-channel receiver performance. Now you might say that the RF power is not off by that much but my interest is having a SOTA radio that greatly exceeds the power of a typical 5 W handheld. On the 70 cm band, this radio only put out 15 W, so only 4.7 dB better than a handheld. The poor receiver performance will tend be an issue on summits that have radio installations nearby. In some cases, this can completely prevent a VHF SOTA activation.

I will probably use this radio again for SOTA activations but I’ll be bringing along a backup rig, just in case.

The post Checking Out The KT-WP12 Transceiver appeared first on The KØNR Radio Site.

When operating portable, I use Lithium Iron Phosphate batteries from Bioenno. Most of my portable operating is for Summits On The Air (SOTA) and I wrote about it here:

My SOTA Battery Journey

For POTA activations, I purchased a larger, 20 Ah Bioenno battery and use it to power a Yaesu FT-991 (and other radios). This battery has worked out really well. It is a bit large for backpack portable and weighs 5.4 pounds, but I have taken it along on a few SOTA activations.

Powerwerx PWRbox

I decided the battery could use a case to protect it while being tossed around in the back of the Jeep. Powerwerx has a really good battery box that includes a digital voltage readout, automotive (“cigarette lighter”) socket, dual PowerPole plugs and high-current binding posts.

Initially, I did not think I needed the extra gizmos, and I did not want to take up more space with the battery system. Later, I figured that I could always pull the battery out of the box and use it in its original form.

The power switch is handy for turning on/off the battery power and the digital voltmeter provides a simple view of the battery condition. Most of the time, I use the PowerPole connectors to connect up my radios but occasionally the automotive socket comes in handy.

I used some of the plastic packing material that came with the box to hold the battery in place. A little bit of cutting with a sharp knife produced a good fit. There is enough room above the battery for the Bioenno charger, so it makes for a nice kit. The charger connects to the original charging plug on the battery.

As expected, Powerwerx did a good job of wiring up the various components and included fuses in both the positive and negative cables. The box is big enough to hold a 40 Ah battery and I am tempted to upgrade it for larger capacity, but the 20 Ah battery has been sufficient, so far.

I’ve used this battery box for multiple POTA activations and a few other situations when I just needed to power up a radio at home. It works great. The voltmeter gives me a quick check of the battery status and the PowerPole connectors make for easy hookup.

The PWRbox costs $109.99, battery not included.

73 Bob K0NR

The post Power Box for Bioenno Battery appeared first on The KØNR Radio Site.

This is a report on my single-operator contest effort during the ARRL November Sweepstakes (Phone) HF Contest. Some other potential titles for this article are:

A Slacker's Guide to Working the Sweepstakes
How To Almost Work 50 States On a Weekend
A Simple Way to Get On the HF Bands

Contests on the HF bands can be a fun way to make a lot of contacts and get some new states or countries. The ARRL Sweepstakes promotes contacts between US and Canadian stations, so it is an opportunity to work those states and provinces.

The Club Challenge

I don’t usually work the Sweepstakes contest but Bill/K0UK put out a challenge to the Grand Mesa Contesters club to get on the air and contribute whatever points you can to the aggregate club score. I thought this was a good idea and decided to join in the effort. I already had committed to teaching a General License class on Saturday, so that limited my operating window to mostly Sunday. No problem, I could still make a significant number of contacts on Sunday.

I read the rules for the contest to make sure I knew the operating times, entry categories, what stations I could work for points, and the contest exchange. Sweepstakes has a complicated contest exchange, that includes a serial number (every contact gets a unique sequential number), precedence (operating class), your callsign, the last two digits of the year you were first licensed, and your ARRL section. Wow. For me, the section is just Colorado (abbreviated CO), but some states have multiple sections. It is a great idea to have the list of ARRL and RAC (Radio Amateurs of Canada) sections available. So the information I gave to the other station was something like this: 105 A K0NR 77 CO. In the example, 105 is the serial number that incremented with each radio contact.

Antenna Project

It turned out that my HF antenna at the house fell down some time ago because the rope holding the wire had rotted away. So my first task was to do a quick but effective antenna installation. We have a 30-foot Ponderosa pine in the backyard, which is my preferred antenna support. I have a number of wire antennas stashed away in my basement, including dipoles, end-fed halfwaves, G5RV’s, etc.

For this contest, I decided to use an end-fed antenna from MyAntennas.com, about 44 feet long. This antenna has a 9:1 matching transformer (an “unun”) that matches the high-impedance of the wire to something closer to 50 ohms. An antenna tuner is required to do the final matchup over multiple HF bands. This antenna is long enough to be effective on 40 meters and any higher band, which matches my usual operating habits. I had a Yaesu FT-950 transceiver available which has an internal tuner that was able to match the antenna on 40m, 20m, 15m, and 10m. This is not an end-fed halfwave…it is a “random” length of wire that is not resonant on any ham band but will radiate pretty well using the matching transformer. The advantage of this antenna is its simplicity and ability to handle multiple bands, with the push of the internal antenna tuner.

My main challenge was to get this antenna up into my favorite Ponderosa pine tree. Again, I took a simple approach. I grabbed my spin-cast fishing pole, attached two 5/16-inch hex nuts to the end of the line (to act as a weight), and cast the nuts up over the top of the tree. This may sound difficult, but it only took me three casts to get the fishing line on a limb that I liked. I let the line out and let the weight drop to the ground. Then I attached a 1/8-inch synthetic rope onto the fishing line and pulled it back up over the tree. Soon, I had my antenna support rope passing over the very top of the tree. It was a simple matter to attach and hoist the undriven end of the antenna to the top of the tree. The antenna is longer than the height of the tree, so I sloped the antenna away from the tree.

A length of RG-8 style coax connected the antenna and the transceiver in the ham shack. I did not ground the antenna transformer or add a counterpoise, hoping that the length of coax would be sufficient to act as a counterpoise. This worked out OK and the FT-950 was able to drive the antenna using just the internal antenna tuner on all bands.

Station Setup

You don’t have to have a computer to log your contacts during the contest, but you really should. Even with 50 contacts written on paper, it becomes difficult to remember which stations you’ve already worked. Also, the logging program automatically generates the serial number mentioned above. Very helpful.

For most contests, I use the N1MM Logger+ software, which is arguably the standard in ham radio contest loggers. It is free to use and is available here. I probably use about 10% of the power of this software but it is relatively easy to use, once you get familiar with it. It has templates for all of the contests, so it keeps track of your score and warns you if you’ve already worked a station. It automatically generates the cabrillo format for submitting your log electronically.

Results

With a 100-watt-and-a-wire station, you have to compete with much more capable stations during a contest. These folks may be running 1kW and gain antennas. I used the “search and pounce” technique, tuning around to find strong stations calling CQ. I typed the callsign into the logging program to make sure we have not already worked and then I called them, just saying my callsign. If they hear me, they will call me back, providing their exchange information. I enter that into N1MM and give them my info. It is as simple as that.

I can usually judge how well my station is doing by how quickly I can contact another station. If they answer me on the first call, that’s great. If it takes a few calls, it usually means that someone else is beating me out in the pileup. I was happy with the performance of the station — I was making contacts at a decent rate.

I made 187 QSOs in about 7 hours of operating, which works out to one contact every 2.5 minutes or so. That rate is not going to win the contest but it was good enough to keep me having fun.

The scoring multiplier for the contest is ARRL and RAC sections, with a maximum number of 84 sections. I worked 66 of them, so not too bad but not a clean sweep. I worked 45 of the 50 US states, missing South Dakota, Oklahoma, New Mexico, Utah, and Alaska. Except for Alaska, the missing states are relatively close to Colorado, so a little more time on 40m (or 80m), for shorter skip distance, would probably have gotten them. The point is that you can achieve Worked All States (WAS) on a single Sweepstakes weekend.

This is a good example of how to get an HF station up and running and make some radio contacts. I often encounter hams that are new to HF and not quite sure how to get on the air. It does not have to be complicated…get a basic transceiver, power supply, coax and a wire antenna and give it a try. Doing this on a contest weekend means that you’ll have plenty of stations to contact.

73 Bob K0NR

The post Working Phone Sweepstakes appeared first on The KØNR Radio Site.

Lately, Joyce/K0JJW and I have been doing combined Summits On The Air (SOTA) and Parks On The Air (POTA) activations. Most of the SOTA summits we activate are inside parks as defined by POTA. Our primary focus is using VHF/UHF from SOTA summits with POTA is being a nice addition. Although the two programs have a lot of similarities, there are some significant differences that need to be understood.

SOTA / POTA Differences

Let’s compare the two programs to understand the differences, so you can have a successful activation with both. We will focus on differences when doing an activation so this is not an exhaustive list.

• Summits Vs Parks. Well, this is the fundamental difference. Summits tend to be small in area, defined by a specific lat/lon coordinate and the surrounding activation zone (AZ). The activation zone is roughly defined as the area surrounding the actual summit, staying within 25 vertical meters. Parks can be almost any size and may cover many square miles. Both SOTA and POTA maintain lists of official summits or parks, so it should be clear whether one of these is valid for an activation.
• Accessibility. While there are drive-up and easy walk-up summits, most SOTA summits require a hike. Many of them are physically challenging. Parks often have easier, park-like access. Or you can always do a 50-mile backpack trip for a POTA activation.
• Equipment restrictions. SOTA allows you to reach the activation zone in a vehicle but you must move away from the vehicle an unspecified distant and operate totally independent of the vehicle. On drive-up mountains, our practical application of this rule is to load up our normal SOTA gear into backpacks, hike away from the vehicle, and set up for the activation. SOTA requires the use of portable power sources but not fossil-fuel generators. This pretty much means battery power, perhaps augmented with solar panels. POTA does not have such restrictions, so if you meet the SOTA requirements you’ll be valid for both.
• Scoring. SOTA emphasizes the accumulation of activator and chaser points, while layering in other challenges such as Summit-to-Summit (S2S) scores. Each summit has a point value assigned to it, based on elevation. In POTA, all parks are created equal and the main focus tends to be on the number of activations and the number of parks hunted (chased).  POTA also has awards for the number QSOs. For example, the Kilo Award is achieved by making 1000 QSOs from a single park (usually over multiple activations). Both programs have quite a bit of variety and flexibility built into their awards and operating objectives, which is one of the reasons people enjoy the programs.
• Successful Activation. SOTA requires only one radio contact for a successful activation. But to receive point credit for the summit, which is what most people are after, you need to make at least 4 contacts. So most SOTA activators define success as getting at least four contacts. The 4 SOTA contacts must be with 4 different stations, with no credit for working the same station on multiple bands. In contrast, POTA requires 10 QSOs for a successful activation.  POTA does count QSOs with the same station on different bands. For example, an activator could obtain the required 10 POTA QSOs by working just two stations on 5 different bands.
• Same Location QSOs. A SOTA activator does not get credit for working another station on the same summit. That is, the other station must be outside of the summit activation zone to be counted. POTA allows an activator to work another activator in the same park for QSO credit. In fact, the activators can receive park-to-park credit for such a radio contact.

VHF SOTA and POTA

Racking up lots of contacts on VHF/UHF from a summit can be a challenge, dependent mostly on the range of your gear and the ham population in the area. Most of the time, we can get four contacts without too much trouble but at times even that can be a challenge. Getting ten contacts for POTA raises the bar higher.

We noted that most of the hams we work on 2m FM are also workable on 70 cm FM. So an easy thing to do is to ask 2m chasers (hunters) to switch over to 70 cm and work us there, doubling the number of POTA-valid QSOs. Interestingly, the SOTA QSO count recorded in the database includes these QSOs. (But you must have contacted at least four unique stations to get the summit points.)

Because Joyce and I usually activate together, we can also work each other for POTA credit. I have discovered that many POTA activator teams make it a standard practice to pull out a couple of handheld radios and work each other on 2m FM when they first set up. OK, maybe that’s not the most exciting QSO of the day, but it is allowed.  With a dual-band HT, you can make two QSOs this way. And it is a good idea to put out a call on 2m FM to work any locals that might be hunting parks. On a summit, these QSOs would not be valid for SOTA, unless one of the operators leaves the activation zone. Yes, we’ve done that, too, taking turns hiking down out of the AZ to make a quick contact.

Summary

This covers some of the things we’ve learned about doing combined SOTA and POTA activations. Again, this is with an emphasis on VHF/UHF operating. You should study the SOTA and POTA rules carefully because this article does not cover everything. However, some of the issues I’ve outlined here are not obvious from the SOTA and POTA rules, so I hope you find this article helpful.

73 Bob K0NR

The post Combined SOTA / POTA Activations appeared first on The KØNR Radio Site.

Adam/K6ARK recently posted this video of his 2m SOTA activation in California. Adam does a really nice job with his videos and this one is no exception. During this activation, he worked KE9AJ in Arizona at 256 miles. This was an FM QSO, with KE9AJ running 6 watts and K6ARK running over 120 watts.

In the video, he shows the 8-element 2m Yagi antenna, which has a clever folding boom design (homebrew, I assume). You’ll notice that he is carrying quite a bit of gear in his pack, including a 160w amplifier, a Yaesu FT-857, several batteries, the Yagi antenna, and antenna masts. Adam has posted other videos of VHF SOTA activity, so check out his YouTube channel for them.

Note that at 256 miles, this is definitely propagation beyond line of sight. We’ve talked about this before: The Myth of VHF Line-Of-Sight.

This has me thinking about some of my best VHF SOTA activations, which I will list here.

Sneffels to Pikes

In 2012, for the Colorado 14er Event, Joyce/K0JJW and I climbed Mt Sneffels (W0C/UR-001) at 14,150 feet in elevation. I worked Stu/W0STU on Pikes Peak (W0C/FR-004). We both were running 5 watts on 2m FM, with 3-element Arrow II antennas. I had an FT-817, while Stu used an HT. We made the QSO without too much difficulty, at a distance of 160 miles. Stu put together this video that shows the action on both summits.

Capulin Mountain

Capulin Mountain (W5N/SG-009) is out in the middle of nowhere New Mexico, a long distance from populated areas. My goal was to activate it (and get the points) on VHF, but I knew it would be a challenge. I put the word out to the weak-signal VHF community and used my FT-817 (5 watts) and 3-element Yagi to make contacts. My best DX was with Arne/N7KA at 184 miles. I could hear him fine on SSB but he could not copy me, so we switched to CW to complete the QSO. Arne used a 2M12 Yagi antenna with 700 watts of power vs my 5 watts.

This turned out to be a good lesson in what happens when the two stations are imbalanced with respect to RF power. My 5 watts vs his 700 watts is a difference of 21 dB. No wonder I could hear him just fine but he was struggling to copy me. Flipping over to CW narrows the receiver bandwidth, improving the signal-to-noise ratio, and was enough improvement to make the QSO.

Capulin Mountain (W5N/SG-009) VHF SOTA

Mount Scott

Mount Scott (W5O/WI-002) is a drive-up summit (elevation 2464 feet) in the Witchita Mountains of Oklahoma. It sticks up high enough to have a good radio horizon in all directions. We stopped there to do an activation in March 2018, using the Yaesu FT-90 (set for 30 to 50 watts) and the 3-element Yagi antenna.

We easily worked a bunch of stations on 146.52 MHz FM, including K5RTN in Brownfield, TX. Later, I checked the distance to Brownfield and found that it was 245 miles, which is still my best SOTA DX on 2m FM. There was probably some favorable propagation that morning, perhaps some ducting, for this to occur. K5RTN was operating from home and I am not sure about his power and antenna.

Threemile Mountain

During the 2021 January VHF Contest, we decided to activate Threemile Mountain (W0C/SP-107), which is usually accessible, even in the winter months. Because it is in the Pike National Forest (K-4404), I did a combo operation of SOTA, POTA, and VHF contest. At 10,020 feet in elevation, it is not the highest summit in the region but it has a good radio horizon in all directions.

Also, the hike is relatively short, so I packed the Yaesu FT-991 and a 20 Ah battery, which gave me more power (50 watts) on 2m and 70 cm. Not only that, I actually fired it up below 50 MHz and made some HF contacts, using single-band end-fed halfwave antennas.

I was working a few stations in Denver on 2m SSB when I heard Larry/N0LL calling me from Smith Center, KS. Larry is a well-known Big Gun on VHF with excellent antennas. I’ve worked him in past contests on various bands and modes but I was surprised how strong he was coming in at Threemile Mountain. We probably had favorable conditions on 2 meters that day but nothing exotic, to make a 372 mile QSO. I’ve worked longer distances on 2 meters but this is my best DX for SOTA.

Radio Fun on Threemile Mountain (W0C/SP-107)

Power and Antenna

Most ham transceivers have decent receivers, so the choice of radio on the receive side is not that critical. (OK, you can add a preamp in front of the receiver to improve it.) The big difference for making QSOs (or not) on 2 meters is antenna and power level.

Improving your antenna is normally the first step in improving your VHF SOTA station, because it helps on both transmit and receive. Joyce/K0JJW and I almost always use the 3-element handheld Yagi from Arrow Antenna. Arrow does not specify the gain, but various sources have measured it at 6 dBd. We have made many QSOs over the years where the extra 6 dB made the difference. An omnidirectional antenna would have come up short. I’ve been looking for a higher gain antenna to use for SOTA but have not found one that I like. Adam’s 8-element antenna is tempting but longer antennas pretty much require a mast, which adds weight to the pack. One of the benefits of the 3-element Arrow is that it is handheld, so we don’t carry a mast. Of course, having two of us activating together really helps…one person can hold the antenna while the other operates and logs. A handheld antenna with a single operator can be a challenge.

Concerning power level, the Capulin QSO with N7KA illustrates what happens when two stations are imbalanced with respect to RF power. After this experience, I did purchase a small 2m amplifier that boosts the 5 watts from the FT-817 to 35 watts. It is compact and not too much of a DC power hog.  I think we also heard an imbalance with the QSO between K6ARK and KE9AJ. KE9AJ’s signal was a bit noisy at K6ARK while K6ARK’s signal was full quieting 59 at the other end. This is not a surprise with K6ARK at around 120 watts and K6ARK at 6 watts (13 dB difference).

For higher power on 2 meters, you generally need to bring a bigger radio or an amplifier. The popular HT is generally limited to about 5 watts. For 2m FM, we’ve been carrying the Yaesu FT-90, which is a pretty compact radio and can put out 50 watts of RF power (FM only). On the Threemile Mountain activation mentioned above, we took the FT-991, which is not very SOTA friendly, but it also does 50 watts on 2 meters…and all modes.

Battery capacity also comes into play as higher power requires more DC current. The FT-90 manual says it draws 9.5 amps at full 50 watts of power on 2 meters. (We usually run it at lower power but will punch it up to 50 watts when required.) The FT-991 manual says it draws 15 amps when transmitting at full power on 2m or 70cm. My 160 watt 2m (Mirage) amplifier can draw up to 30 amps on transmit. Wowzy, that’s some real current! The point is that as you increase power, you need to look at your battery situation more carefully.

It might sound like I am suggesting that we should maintain a power balance between the two stations. That’s not the case and is often not even practical. When one station is much stronger than the other, it can be used to advantage. The stronger station is easily heard and the weaker station can point the antenna in the right direction to peak up the signal. The weaker station consistently hears the stronger station, so now the challenge becomes to just get a few seconds of successful transmission in the opposite direction. You keep trying until the weaker station manages to get through. Compare this to having two lower power stations trying to make a contact. They may not even hear each other at all because the antennas are not pointed optimally. When they do hear each other, they are both struggling to hear the other station and complete the QSO. This lowers the probability of completing the contact.

So how much power should you run on 2 meters for SOTA? Of course, More Is Better, except for the extra weight in your backpack. The difficulty of the hike comes into play…on shorter hikes, weight does not matter so much. I am finding that 5 watts is on the skimpy side. On the other hand, going much above 50 watts requires larger batteries, so I am thinking the sweet spot is around 30 to 50 watts. If I do happen to work a base station running 1kW, my signal will be 13 dB lower with 50 watts (worst-case scenario). This is just my opinion, your mileage may vary.

Summary

So can we all agree then that VHF signals can go beyond line-of-sight? These examples are basic tropospheric paths and do not include the exotic propagation modes such as meteor scatter, sporadic-e, aurora, EME, etc. I’ve used most of those modes to work longer distances but not during a SOTA activation. Most hams know that SSB and CW are more effective than FM when signals are weak. In fact, FM weak-signal performance is lousy. Still, we see multiple examples of making some long-distance contacts with FM.

73 Bob K0NR

The post How Far on VHF SOTA? appeared first on The KØNR Radio Site.