When discussing signal levels and power output, hams like to say things like:

Using higher power isn’t important because it only gives you one additional S unit

and

You’ll lose some power in the coax but you won’t even notice a few dB

These statements are often true and at the same time may be completely wrong. I’ve noticed that radio amateurs pushing the limits of their station pay close attention to every decibel they gain or lose. This is especially true at VHF/UHF frequencies where signals may be weak. A dB here, a dB there, the next thing you know it adds up to something big!

Definitions

First, let’s make sure we have a few definitions right. The decibel (dB) is defined as the ratio of two power levels:

dB = 10 log (P2/P1)

One decibel corresponds to a 26% increase in power level. A well-known rule of thumb is that doubling the power corresponds to a 3 dB increase. Similarly, chopping the power in half drops the signal level by 3 dB.  A 10 times increase in power is 10 dB. (Voltage can also be used to calculate decibel relationships but to keep it simple, I’ll just use power.)

The S Unit is normally defined as a 6-dB change in signal level, which is a factor of 4 in power. (Your S meter may or may not actually follow this rule but that is a topic for another day.)

Power Level

Let’s compare a few different power levels to get a feel for how decibels and S units behave. Let’s use a 5 watt QRP level as our reference power. If we crank up the power to 100 watts, we  have 10 log (100/5) = 13 dB increase in power level. This is slightly more than two S units (2 x 6 dB), so we would expect the S meter on the other end to read 2 units higher.

Now suppose we kick in our linear amplifier to produce a 1 kilowatt RF signal. This power level is 10 log (1000/5) = 23 dB higher than the 5 watt signal, or roughly four S units.

Now if our QRP signal was a solid S9 to start with, adding another 23 dB on top of it may not be that significant. The station can be heard at S9 or can be heard even louder at S9 + 23 dB. Except when there’s a pile of stations all calling that rare DX…then the loudest station tends to be heard. Crafty operating skill and good luck may overcome the power difference.

But consider the other extreme. Our QRP station is being heard right at the noise floor on the receive end. The two stations are struggling to complete the contact and the propagation path degrades by 2 dB. Now the QRP station is below the noise and uncopyable. We increase our power to 100 watts and gain 2 S units…still not very strong but the ability to receive the signal improves dramatically. Crank it up to 1000 watts and you gain another couple of S units and the copy is quite good. The key point is that changes in signal level matter most at the margin, when you can just barely copy the signal. (By the way, there is nothing wrong with running QRP…many ops enjoy the challenge of making contacts with low power.)

At the receiver, our ability to recover the signal is determined by the signal-to-noise ratio (SNR). A higher noise floor at the receiver means it will be more difficult to hear the signal coming in. The type of modulation being used may also make a big difference. Good old CW and the WSJT modes use a narrower bandwidth and will get through when wider-band modulation (SSB, FM) fails. In all cases, a stronger signal works better.

Antennas

Antenna systems also increase our signal level…and they do it for both transmit and receive. I recently did some comparisons of VHF antennas from a SOTA summit. My 2m Yagi antenna has 6 dB of gain (referenced to a dipole) and my comparisons showed that the performance of this antenna was good enough to pull some signals out of the noise to be solid copy. This occurred when the other station’s signal was right at the noise floor (using my lower gain antennas) such that the 6 dB improvement had a significant impact.

Sometimes hams will say that VHF is just line-of-sight propagation and that the signal level doesn’t matter much. This is partially true but often we are stretching for contacts beyond line-of-sight. Take a look at this article: The Myth of VHF Line-Of-Sight. This is another case where we are operating on the margin and every dB matters.

Feedline loss can cause us to lose decibels, which impacts both transmit and receive performance. If your coaxial cable is short, then the losses may be negligible. Increasing cable length and increasing frequency produce more loss. For example, 100 feet of RG-8X has only 1.1 dB of loss at 10 MHz. Increase the frequency to 146 MHz and the loss jumps to 4.5 dB, using the Times Microwave cable calculator. That means 50 watts of power at the transmitter turns into 17.7 watts at the other end of the cable. Using LMR-400 coax reduces the attenuation to 1.5 dB.

Summary

You can choose to ignore small changes in your signal level. A dB here or there may not make a big difference with casual ham radio operating. But these losses tend to add up and may become significant. Most importantly, just a few dB may be the critical difference between making a radio contact or not, when operating at the margin.

The post A Decibel Is Still A Decibel appeared first on The KØNR Radio Site.

Getting out on the road and exploring is always fun, especially if you have ham radio on board. Joyce/K0JJW and I have been doing quite a bit of travel lately and we just completed our longest road trip so far with our RV.

Our main destinations for the trip were four national parks: Congaree NP, Biscayne NP, Everglades NP, and Dry Tortugas NP. This determined the main route but we also found plenty of other things to do along the way. We started in Colorado, cut the corner across New Mexico into Texas, then east through Oklahoma, Arkansas, Mississippi, Alabama, Georgia and South Carolina. Then we headed south to Florida and ended up in Key West. Our return trip followed the gulf coast back to Texas, then back home.

Travel Philosopy

Planning a trip is full of trade-offs, so it is useful to have a general approach that the participants agree on. Our approach to this trip was to not drive too far every day but drive enough to hit the various places we wanted to visit. We are still working to find the right balance. This trip lasted 39 days, covering 6000 miles, which is about 150 miles per day. Some days we drove very little and other days were longer, maybe 400 miles.

Although the trip was created around the national parks, we filled in with interesting stops along the way. In particular,  we like to camp at state parks: the campgrounds are great and there’s usually something interesting about the park to enjoy. And did I mention they are natural Parks On The Air (POTA) opportunities? We also tried to work in some Summits On The Air (SOTA) activations that are relatively easy to access.

Rocky Victoria

Our recreational vehicle (RV) is a 2018 Winnebago Paseo, built on a Ford Transit chassis. We named her Rocky Victoria, using non-standard phonetics, but usually just refer to her as “Rocky”.

Compared to your typical car or SUV, this Class B RV is huge. Compared to other RVs, this vehicle is small, about 22 feet long, usually fits in a standard parking space. With all of the normal RV stuff installed (stove, microwave, sink, refrigerator, toilet/shower combo, bed, etc.) there is not a lot of room left for personal gear.

Rocky fits us really well because it is easy to drive, getting in and out of places without much hassle. Also, setup and tear-down time at a campsite is minimal. One limitation is poor ground clearance, which is fine for forest service roads in good condition but not appropriate for offroad use. This affects what SOTA and POTA activations we do.

Radio Gear

We have an ICOM IC-2730A in Rocky, for normal 2m/70cm FM comms while running down the road. The antenna (not visible in the photo) is just a short whip on the driver’s side of the hood.

Rocky is not a big RV so by the time we load up all of our stuff, it is full. So the radio gear (and everything else we take along) must follow the backpacker principle of “take only what you need, use what you take.” No room for extra stuff you don’t use.

For this trip, we took along two ham stations:  A basic VHF SOTA station and a capable, picnic-table POTA station.

VHF SOTA Station

The VHF SOTA station is very compact and easy to carry. It covers the 2m and 70cm bands on FM, which is usually sufficient for us. The RF output power is only 5W, so it does not have the punch of one of our higher power radios. Not a bad tradeoff though.

Two Yaesu FT-1DR 2m/70cm handheld transceivers
Arrow 3-element Yagi 2m antenna
Two RH 770 dualband SMA antennas
HT chargers and other accessories

Picnic Table POTA Station

The POTA station is built around the FT-991, which is a 100 watt transceiver (HF/VHF/UHF) that is reasonably compact. We use a 20 Ah LFP battery to power the radio so it is portable and independent of the RV power sources.

Yaesu FT-991 Transceiver (HF, 6m, 2m, 70cm)
End-fed halfwave antennas for 40m, 20m, 17m, 15m, 10m
Roll-up j-pole antenna for 2m/70cm
20-foot fishing pole to support antennas
Two 25-foot lengths of RG-8X coaxial cable
12V, 20 Ah LFP Battery (Bioenno Power)

The POTA station does a great job at a campsite, usually on a picnic table. The POTA station fits inside my Kelty backpack so it can be taken for a hike. It is a bit heavy for a typical SOTA summit but works OK for drive-up and short-hike summits. It can also be set up inside the RV if required.

Typically, we are going to try operating on 20m or 17m so that the halfwave antenna easily hangs from the fishing pole support. Depending on conditions, we often have to use 40m which takes a little more work to hang. Not a huge problem, though.

For portable operating, I’ve tended to use a variety of end-fed wire antennas supported by a non-conductive pole of various sizes. For this trip, we used a 7 meter (21 feet) telescoping fishing pole that collapses to about 30 inches.  This pole will fit into my SOTA backpack.

To support the fishing pole directly from the RV, I attached a short length of plastic pipe to the ladder. It is a simple matter to slide the pole into pipe, resulting in the top of the pole being about 26 feet off the ground.

The combination of the two stations gives us a lot of options for ham radio operating.

Summits On The Air

We activated three summits along the way: Mount Scott (W5O/WI-002) in Oklahoma, Choctaw County HP (W5M/MS-001) in Mississippi, and Monte Sano Mountain (W4A/HR-002) near Huntsville, AL.

Monte Sano Mountain turned out to be a unique location because it is located in the Monte Sano State Park. The park surrounds the summit, which is broad and flat. We determined that the park campground is within the activation zone, so we camped there and did both SOTA and POTA activations.

Parks On The Air

We did a number of POTA activations along the way. This was done opportunistically, typically in the afternoon after we had set up our campsite. Our radio operating used SSB on 20m or 40m, along with a few 2m FM contacts.

K-0688  Lake Meredith National Recreation Area   US-TX
K-1090  Lake Chicot State Park   US-AR
K-1048  Monte Sano State Park  US-AL
K-0017  Congaree National Park US-SC
K-1832  Anastasia State Park  US-FL
K-0024  Everglades National Park  US-FL
K-0635  St. George State Park  US-FL
K-2992  Brazos Bend State Park  US-TX

Every one of these activations was a lot of fun. There’s nothing like sitting outdoors in the sunshine working a pileup of enthusiastic POTA hunter stations.

Summary

In this post, I emphasized the ham radio activity during this trip. Radio operating was not our main goal but it was a big part of the overall experience. Joyce and I had a fantastic time touring this section of the country, and we are looking forward to our next trip.

73 Bob K0NR

The post Parks, Summits and Roadtripping appeared first on The KØNR Radio Site.

Joyce/K0JJW and I did another activation of Mt Herman (W0C/FR-063) today. This is a repeat summit for us this year but we were looking for an easy hike not too far from home.

As usual, we were just using the VHF/UHF bands for the activation. My favorite rig for this type of SOTA activation is a Yaesu FT-90, a very compact mobile transceiver (4 x 1.2 x 5.4 inches) that is no longer manufactured. It has a unique heatsink with an integral fan that can handle the heat from the 50-watt transmitter.  We use a Bioenno 4.5 Ah LFP battery to supply the power for the radio.

I was trying to work Bob/W0BV about 65 miles away and we were not able to complete the contact. The distance is not too difficult but there are several mountain ranges in the way. Sometimes we can get the electromagnetic waves to sneak through, but not today. Hiking down the mountain, I was thinking about how we could have probably made the QSO on SSB or CW, instead of FM.  I chose not to bring the all-mode transceiver (FT-817) along today, so that was not an option.

That is when the idea hit me. The FT-90 is the right form-factor and power level for VHF/UHF SOTA but it is limited to FM. Yaesu, if you are listening, here’s what I’d really like to see in a small mobile transceiver:

• FT-90 size radio, perhaps a little larger but not much
• 2m and 70 cm bands (include 1.25m if you’d like)
• At least 25 watts of output power, more would be better (say 50 watts)
• All mode capability (CW/SSB/FM/Digital), sure go ahead and toss C4FM in too.
• No internal battery…I’m going to have to use an external battery anyway to get enough battery capacity

At various times, I have had people ask “why don’t they put SSB in handheld radios?” They recognize that SSB has weak-signal advantages over FM, so they wish their handheld transceiver (HT) could do it. I say rather than shove more features into an HT, put it in an FT-90 size radio. It would be a much more usable solution.

Although I arrived at this radio concept thinking about SOTA, it would also be a great mobile rig for general use. The FT-90 was popular because it was very compact AND it had a removable faceplate that could be mounted almost anywhere. There really is no way to get VHF/UHF SSB into a vehicle other than those all-band radios like the FT-857 and the IC-7100. Oh, did I say FT-857? Sorry, that model has been discontinued. The satellite operators will love it, too, especially if it could work 2m/70cm crossband full-duplex.

So there you go, Yaesu (or Icom)…a fantastic product concept at no charge. I would be happy to beta test it for you.

That’s my idea for today. What do you think?

73 Bob K0NR

The post Here’s the SOTA Transceiver I’d Really Like appeared first on The KØNR Radio Site.

Many of us hams, SWLs, and makers buy inexpensive electronics from China. It’s become a bonanza for small, cheap and surprisingly good radio-related gadgets and parts on eBay and other vendors. I buy a fair amount, most recently a recommended project box for a set of HF bandpass filters I purchased from a small company in Australia. It finally arrived and is superb for a very cheap price!

But there’s a dark side. I love a bargain more than most. But when it’s an illegitimate clone of another genuine manufacturer’s product, that’s no fair. Yep, there’s ways to legitimately copy another design with various hardware licenses and beaucoup software licenses (if that’s relevant to the product). One of the ongoing issues in the Pacific Rim to the rest of the world has been the taking of the intellectual property from others, making a cheaper product offered for sale, and using the trade naming and hardware/software designs of the originating manufacturer. In short, stealing for profit.

So be careful. The fake copies may not work with the latest SDRplay software including SDRuno. There will be no technical support even if you get some limited functionality using out of date software.

Jon Hudson SDRPlay.com

For those in or interested in the SDR receivers available, there are a number of prominent names. I’ve had an Italian Perseus SDR for over a decade. Paid the asking price (a lot by today’s standards). It’s a terrific product although aging in the technology of the design. The SDRPlay company in England has risen to the top in terms of performance, continued innovation and the software they purchased for a free download to their legitimate customers. SDRUno is a terrific software package which they continue to update. They have an API so other software makers (like Simon Brown with SDR Console) can drive the SDR car, too. Their price points are very good and appropriate for the various receiver models they have on the market. A third-party individual has written code for a continually updated package that implements a Spectrum Analyser for most of the SDRPlay receivers. I’ve used an old (no longer in production) RSP1 with it and it’s very cool! And don’t get me started on their tech support and education. Mike Ladd KD2KOG is the Dude on social media for SDRPlay and related products. Mike creates new markets for SDRPlay products by educating hams and listeners on creative new ways to use them.

Individual preferences for one SDR product or another aside, SDRPlay is a legitimate company that plays more than fair in the marketplace. They do a lot to support the various elements of the radio hobby that we all enjoy. We should return that favor so that they can continue without the eroding effects of illegal clones undercutting their market, n’est-ce pas?

In Episode 344 of the ICQ Podcast, we covered a news story about illegal fakes of the RSP-line of SDRPlay receivers being sold through various online sales venues. I made the suggestion that there’s a means for honest members of the amateur radio and SWLing community to help. On both eBay and Amazon (Ed DD5LP pointed out Amazon), there is a simple quick procedure to report fake or illegal clones or deceptive use of trademark identification on items for auction. I actually reported six (6) during the recording of the podcast!

Here’s what you do. I’ll pattern it after Jon Hudson’s blog post at SDRPlay.com that he published after I sent him a note of my statements on the podcast that drops today. It only takes one minute to do.

If you search eBay for the term “sdrplay,” you can get a string of hits returned, some of which are completely legitimate. For instance, SDR-Kits in the UK is a bona fide reseller of SDRPlay receivers (and another really good international seller of VNA and related test equipment!). Some might be individuals offering personal units for sale. But many are effectively selling fake clones. Here’s the first hit I got when I just did this search on eBay. Heck, it’s even a SPONSORED auction!

Clearly, it’s labeled as an SDRplay RSP1A but real owners who have looked at the SDRPlay website will recognize that it is a “black box” clone. Here’s the next step:

Once you find the Report Item tab, here are the options you should select to report it as a fake clone in violation of eBay’s stated terms of sale. I’ve added a brief narrative in the Brief Description that gives eBay your claim and the website through which to validate that it’s a clone:

Don’t think that just repeatedly filing a claim on the SAME clone auction is doing even more good. It won’t. It will just slow down the process.

After you click the Submit Report button, your submission will be greeted with the following response:

While this action on your part might appear to be vindictive, it’s not in light of what the nefarious seller is doing to the legitimate amateur radio and SWL marketplace of legitimate products. IF enough of us engage in this public service, it will greatly help eBay and companies like SDRPlay continue to provide legitimate products to the marketplace. It only takes a minute!

Charlie/NJ7V and Gaston/KT1RUN did a comparison of VHF antennas during a SOTA activation. Specifically, they compared a rubber duck antenna, a J-pole antenna on a tall mast, and a 3-element Yagi antenna. Spoiler Alert: the rubber duck sucks (they all do) but the Yagi and J-pole performed about the same.

Joyce/K0JJW and I use the Arrow 3-element Yagi antenna for most of our SOTA activations, so I am very familiar with that one. We also have a rollup J-pole that we use once in a while.

Charlie used the Yagi the same way we do: handheld at ground level. The J-pole was on a mast, maybe 12 feet (?) in the air. Although they were on a summit, there is some performance improvement getting the antenna higher than the surrounding terrain. The gain of the Arrow 3-element Yagi has been measured at about 6 dBd. The gain of a J-pole, being a halfwave radiator, is 0 dBd. The additional height of the J-pole has to make up this 6 dB of gain difference to be roughly equivalent.

A big difference, though, is that the Yagi antenna has to be held and pointed. The J-pole is always pointing in the right direction so you can just focus on operating and logging. We may have to consider using a omni antenna instead of the Yagi.

Good stuff!

73 Bob K0NR

The post Best VHF SOTA Antenna? appeared first on The KØNR Radio Site.

Once again, I was asked by a new ham “which handheld transceiver should I get?” This is a frequent and valid question that comes up. Often the question gets framed as “Baofeng or something better?” I say “something better.”  I am not writing to bash Baofeng radios or the people that use them. The radios are an incredible value on the low end of the market…amazing what they can do for $30 or so. Besides, I own several of them.  I just think that if you have a few more $$ to spend, you can get a much better radio. What’s wrong with these low-end Chinese radios? Out of spec harmonics on transmit and poor adjacent channel rejection on receive.

Digital? Probably Not

The other question that usually surfaces is “should I get a digital radio?” Here “digital radio” means D-STAR, Yaesu Fusion or DMR. My answer to that is “No,” unless you have a specific reason for going digital. Adding digital to a radio results in two things: 1) a higher price and 2) a more complex radio. Actually, the price difference may not be that significant, especially for a DMR radio. However, the complexity factor is always there.

What is a specific reason for going digital? You already know that there are digital repeaters in your area that you want to use, you have ham radio friends already using digital or you are technically-oriented and have researched the topic to know that it is something you want to try. If one of these things is true, then go for it.

Oh, you do need to know which digital format to get. No radio does them all and the industry is fragmented between D-STAR, Fusion and DMR. I find this very disappointing but life is sometimes like that.

Narrowing It Down

So narrowing the topic down, we are looking for an affordable (under $100) dual-band handheld that is not a cheap Chinese radio (Baofeng, etc.) and is not a fancy digital radio. My opinion is the quality ham radio manufacturers are pretty much Alinco, Icom, Kenwood, and Yaesu. The price points on basic handheld transceivers keep changing, so be sure to check the date on this post and do a little price shopping.

The Alinco DJ-VX50 is about $100, so not too expensive, but I am not seeing any eham.net product reviews on it. Also, it seems to be out of stock at several vendors, so I am not sure of its production status. Icom and Kenwood have exited the low-end handheld market, so nothing to consider there. This leaves Yaesu as the only “brand name” player in this space. I have been recommending the Yaesu FT-4XR as a good alternative: see What About the Yaesu FT-4XR? at about $80. I recently noticed that the Yaesu FT-65R has come down in price to about $85. With this price difference, it probably makes sense to go with the FT-65R. (I really wonder about Yaesu’s product line strategy at this point. Why are there two similar radios priced so close together?)

Here is a quick comparison of the two radios: Yaesu FT-4XR vs FT-65R, which is right for you? Conclusion: FT-65R is probably better for most people. Also, check out the HamRadioSchool.com article: Yaesu FT-65R Product Review.  The eham.net product reviews are generally positive on the FT-65R, but there are a few negative themes that surface. Some people are reporting radio failures that may indicate a manufacturing issue with the product. (It is made in China.)

The Good Old FT-60

The other theme that surfaces is that the FT-65R is not a complete replacement for the venerable FT-60R. Joyce/K0JJW and I have a couple of FT-60Rs that we really like and frequently use. Yaesu still sells this older model because it is so popular and, frankly, it is a really solid radio. The HamRadioSchool.com review of the FT-65R mentions several things that people tend to like on the FT-60R that were left out of the FT-65R (e.g., dedicated VFO and Squelch knobs.) The biggest complaint I hear about the FT-60R is that it has an old-school NiMH battery (the FT-65R has lithium-ion).

My conclusion is to recommend the FT-65R to newcomers to the hobby. At ~$85, it fits most people’s budgets. There is some risk that you will outgrow it down the road and want a more capable handheld for digital or APRS or whatnot. In that scenario, the FT-65R will still be a good second/backup radio. (Ya gotta have more than one, right?)

That’s my opinion. What y’all think?

73 Bob K0NR

The post Choosing A First Handheld Radio appeared first on The KØNR Radio Site.

Some folks are criticizing the ARRL for not modifying the Field Day rules in response to the Wuhan virus epidemic. Most of them are looking for a way to operate Field Day from home but still have a club score of some kind. I posted my thoughts here: Don’t Mess With The Field Day Rules.

The Field Day (FD) rules allow for a home station with commercial power to participate in FD as a Class D station. However, Class D stations cannot work other Class D stations for points. If the home station has emergency power (batteries, gasoline generator, etc.), then it is a Class E station that can work all FD stations for point credit.

Emergency Power: Too Difficult?

I’ve heard some hams argue that it is too difficult to set up emergency power for their home station. In many cases, the argument is actually that it is too expensive to do this.  I can see this point if you run out and buy a name brand gasoline generator…a Honda EU1000i costs about $950.

This raises the question of what is the lowest-cost way to equip a home station for emergency power?  Let’s consider the case of a typical 100W HF transceiver such as an IC-7300 or FT-991A. These radios require a 12 V power supply at 22 A maximum on transmit. Receive current is much lower, typically 1 to 2 A. Under FD rules, we don’t need to power our computer or other accessories from emergency power, just the radio. If we assume a 50% duty cycle, this class of radio consumes about (22+2)/2 = 12 A average current. (Yes, you could choose to operate QRP and really stretch the battery but let’s stay with the 100 W scenario.)

Get A Battery

So what is the cheapest way to get this done? Let’s take a look at using a deep-cycle battery. Walmart has an RV/Marine battery for $75, rated at 101 AH. Assuming 12 A of current, this battery would support about 8 hours of radio operating. This is going to be way short of the 24 hour operating period of FD but it might be enough to support a less intense operation.  We could also do some things to stretch out the battery life, such as reducing our transmit power. Dropping to 50 W would roughly double the operating time to 16 hours, which should be enough for a single-operator station.

Of course, another option is to double the battery capacity by using two batteries. These amp-hour ratings on batteries are always a bit idealistic and our transmit duty cycle might be more than 50%. Let’s assume we buy two batteries to give extra margin and allow us to run 100W. We will also need a simple charger, which costs about $25. So there you have it, 2 x $75 plus $25 = $175 for a decent emergency power source.  (If we decide to use only one battery, the cost drops to $100.)

Now $175 is a significant investment and only you can judge how well your ham radio budget can support this. For many people, this is affordable and the real question becomes is this how you want to spend my hard-earned cash.

This is my best shot at a low-cost emergency power source. Do you have a better idea?

73 Bob K0NR

The post How Much Does Emergency Power Cost? appeared first on The KØNR Radio Site.