UFYQL F156P02 15.6in Portable Monitor Mini Review

The UFYQL F156P02 15.6in Portable Monitor is certainly not the fanciest available, but it is a very inexpensive way to get more screen space

A short and maybe not-so-sweet HF antenna

A lot of information has been posted online recently about very short portable vertical antennas. There must be some magic in how they work, surely, since they appear to disobey the laws of physics. I used to own one called a “Miracle Antenna”; it was manufactured in Quebec, Canada. It comprised a 57-inch telescoping whip mounted on a remarkably well-engineered toroidal loading coil with many taps selectable by means of a rotary switch. The Miracle Antenna could be used from 80m up to 70cm with a suitable counterpoise. The loading coil switch had a bypass position so that the antenna could be used as an unloaded whip for VHF/UHF. The 57-inch (~1.5m) whip is a three-quarter wavelength on 2m; 70cm could be selected by shortening the whip.

I made lots of contacts!

I was thoroughly impressed by my Miracle Whip; I made lots of contacts with it. Really; it worked remarkably well – but only on VHF. Perhaps if I had tried harder with it I could have snagged some QSOs on HF too, but that never happened. It was relegated to the role of a great 2m band antenna used for accessing my local repeater.

So what’s up with very short antennas?

First, let me dispel one myth about them. With a suitable transmatch (tuner) or adjustable loading coil, a nice low SWR can be obtained even from the shortest of shorties. Let’s say you can tune for 1:1 SWR on multiple bands. Great! Now key up and start working the pile-ups! Yes? Or no?

Whoa … Not so fast pilgrim!

The SWR that the radio sees results from a private negotiation between the transmatch and the radio; the antenna doesn’t enter into it. Compare it to a wild west cowboy town. The local sheriff maintains law and order inside the town, but outside the town it’s still the untamed wild west.

The SWR at the feedpoint of a very short vertical antenna (excluding loading coil) is very high. That high SWR is presented to the “tuner” as a high impedance that the “tuner” transforms to 50 ohms resistive, or close to that value. That “varmint” of a shortie antenna remains a wild, untamed, high SWR beastie. Why is that?

There is another factor to consider and it is critically important. It’s called Radiation Resistance (Rrad). Rrad is a strange animal in that a high Rrad results in higher efficiency of the antenna. Very short antennas have a very low Rrad. I set up a 57-inch whip on a tripod and attached a 17ft counterpoise, them measured the Resistance and Reactance on the 20m band. The numbers I obtained were 1.98 – j53 ohms. The reactance value (X = -j53) was actually a lot better than I expected and I have a theory about why that is. I will explain later in this post.

Now let’s look at how antenna efficiency is calculated. An antenna has two types of resistance; Radiation Resistance (which is good) and Loss Resistance (Rloss which is bad, very, very bad). Loss resistance includes every connection between components in the antenna system, ohmic loss in any loading coils as well as ground loss in the counterpoise system. Efficiency is the ratio between Radiation Resistance and total resistance:

Efficiency = Rrad/(Rrad+Rloss)

Lets assume the Rrad value is equal to the real component of the antenna’s impedance; in the example given above that’s 1.98 (let’s call it 2) ohms. Determining the value of the total loss resistance is not easy. There will be a few ohms of resistance in all the connection points and definitely in the loading coil – especially for a base-loaded vertical since the current is at a maximum at the antenna feedpoint. But the biggest losses may come in the ground system.

Typically, from accounts I have read, operators often lay just a single counterpoise wire on the ground. The current in this wire will be the same as the current in the radiating element and will be almost totally lost in the ground.

Now, let’s look at how my experimental shortie vertical antenna would perform if I took it out to the field. And, also, let’s assume I used a base loading coil to resonate it instead of a tuner. If I adjusted the coil to give a 1:1 SWR guess what? That would be VERY BAD, VERY VERY BAD. Here is why:

We can insert the value I measured for Rrad into the efficiency formula given above:

Efficiency = Rrad/(Rrad+Rloss) – inserting measured value of Rrad: Efficiency = 2/(2+Rlos).

Since we have also measured an SWR of 1:1 the feedpoint impedance is 50 ohms (resistive) comprising the total of Rrad + Rloss.

Now we can deduce the value of Rloss as the difference between the 50 ohm resistive impedance at the feedpoint minus Rrad. Rloss = 50 – 2 = 48 ohms.

So the efficiency of our shortie antenna can be calculated as 2/50 = 4%.

Gadzooks!!!

If little shortie is used with a QRP radio putting out 5 watts into the antenna, the actual radiated power will be only 4% of 5 watts = 200 milliwatts. That’s sad.

Hey Jude, don’t make it bad

“Take a sad antenna and make it better”. There are two ways to make an antenna better. We can increase its radiation resistance or reduce its loss resistance. The first way is very easy; the second is more difficult. To increase its radiation resistance all we have to do is make it longer. We know that a half wave antenna has an endpoint impedance that is resistive and very high – typically 2000 ohms or more. If we plug that into the equation we get an efficiency of 2000/2000+48 = 98%.

“What a load of horse feathers, I still make plenty of contacts with my short vertical”

Yes, of course your 200 milliwatts will still be heard and you will still make contacts. Let’s introduce another bit of physics to explain why. It’s called the Inverse Square Law. It states that the strength of your signal is proportional to the square of the distance between the transmitting station and the receiving station. Modern HF receivers are very sensitive and can receive signals down into the microvolt range. If the receiving station has “big ears”, i.e. a big efficient antenna, it has a better chance of picking up very weak signals and will hear your 200mW signal. But at a certain distance the Inverse Square Law dictates that the strength of your signal will have fallen below the threshold at which even Big Ears can detect you. But, the Inverse Square Law applied to stations closer to you means your 200mW will still be heard.

If the DX can hear you, can he still work you?

Now let’s look at another situation in which Big Ears can hear you fine business and replies to your call. Now yet another bit of physics comes into play – it’s called the Reciprocity Principle. Simply put it states that an antenna’s transmit efficiency is the same as its receive efficiency. So Big Ears is calling you but you may not be able to hear him.

There’s no free lunch

There are lots of shortie antennas available. If you choose to build, or buy one you will have to accept that, while you may have fun with it, it has limitations. When propagation is good you may even get some pleasant surprises.

Oh, I see, that’s why …

Finally, I wrote earlier in this post that I was surprised at the relatively low capacitive reactance of the shortie antenna I put up for testing. I think I can explain why. At my home QTH in southern Ontario, Canada, winter hasn’t finished its dastardly doings yet. It was way too cold and windy outside to venture out onto the planet’s surface for antenna experiments, so I set up my 57-inch whip on a tripod inside the house and laid 17 feet of wire across the floor as a counterpoise. It is possible that this appeared as an ungrounded Off Center Fed antenna to my RigExpert antenna analyzer. The total length was just under 22 feet which is about 2/3 of a half wavelength on 20m. The analyzer might then have perceived this as a less inefficient antenna than a short vertical (0.075 wavelengths on 20m) worked against an electrical ground.

Help support HamRadioOutsidetheBox

No “tip-jar”, “buy me a coffee”, Patreon, or Amazon links here. I enjoy my hobby and I enjoy writing about it. If you would like to support this blog please follow/subscribe using the link at the bottom of my home page, or like, comment (links at the bottom of each post), repost or share links to my posts on social media. If you would like to email me directly you will find my email address on my QRZ.com page. Thank you!

The following copyright notice applies to all content on this blog.

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

I have hyperhydrosis on my hands, feet, and under arms. I lost count of the amount of keyboards I've had to replace, both internal in my laptops and external usb ones. I know there are silicone options, but they are very mushy, often have strange layouts, and are full-sized. I am totally blind, so I need both tactility and the layout to be normal, or at least, close to it. I tried at least one a keyboard cover, but it made it very difficult to feel the keys, since it was thick and felt like a single sheet of silicone, even though it did have the spaces for each key.

This is my ideal keyboard in both layout and size, next to that on the Acer Aspire One D270, which is perfection. But I've gone through about seven of them already, because I keep shorting out keys. I try to remap them, but after awhile, it just becomes annoying.

CUQI Mini Keyboard, Small Wired 82 Scissor Keys, USB Interface

https://www.amazon.com/dp/B0C26RZBRJ

I bought this last month. It's okay, but I always have to use Auto Hotkey to add an Applications key and reverse the left Alt and Windows keys. Plus, not all programs recognise the changes. I have no idea how long it will last, either, since this is my first one. But at this price, I don't want to keep buying them. It's not portable enough to fit in my bag with my tablet, but it's thin, light, and not huge.

ALLIFE Universal Ultra Light Slim Portable Wireless Bluetooth 3.0 Keyboard

https://www.amazon.com/dp/B09GKFJM5D

This is good for phones, but it doesn't contain the F1 through F12 keys for Windows.

ProtoArc Foldable Compact Keyboard, XK04

https://www.amazon.com/dp/B0D9PT9884

I bought this a few days ago, precisely because it's supposed to be waterproof. They say it's for my Toughpad, which is a seven-inch tablet, but it's a giant, full-sized keyboard! Why they would make this for such a small machine is beyond me. That said, if this were compact, it would be perfect, since it's rigid with good key tactility. While they say it's mechanical, don't expect anything like a Model M.

BoxWave Keyboard Compatible with Panasonic Toughpad FZ-M1 MK3 (7 in)

https://www.amazon.com/dp/B0DJ3NT9G9

I've tried a few others, from folding to solid, but many were missing essential keys (most noteably the F1 through F12 keys) and some were simply ruined very quickly. Can anyone help me find a good, portable keyboard that can withstand my sweat?

#accessibility #blind #computers #hyperhydrosis #keyboards #portable #sweating #technology

I’ve skated on my one arborist bag throwing lesson from @beckett long enough.

I think I’m going to have to break down and watch some youtoob videos on technique. My willow oak humbled me today 😅

Recommendations, Mastodon.radio?

#NewHam #NewHams #Throwing #Antennas #Portable #pota #AmateurRadio #hamradio

Be gone pesky radials!

One of the biggest bugbears of portable operations in a public space when using a vertical antenna is having to lay out radials – either on the ground, or raised. I have told the story of the dancing lady before on this blog; she performed a little jig when advised to be careful of the wires on the ground. Some of the parks I frequent are quite small and busy in the summer months, so I always have to be cautious about creating a potential hazard for other park users.

Even if I find a nice quiet area along a trail, there is often limited space in which to spread my wires. Alternatively, I may be on a mission to operate with multiple rapid deployments – drop my pack, super fast setup, operate, move on. A small vertical antenna is a very convenient way of getting on the air with minimum fuss – except for the radials.

What is the function of radials?

It doesn’t matter whether the radials are on the ground or raised, they form a counterpoise – “the other half” of an antenna. The current flowing through the radial system controls the current flowing into the radiating element. An efficient set of radials allows maximum current to flow through the whole antenna system. The current flowing in the radiating element is equal to the current flowing into the radials. More current equals more signal being radiated.

We can throw a single wire on the ground and call it a counterpoise – there seems to be a magic length of 17 feet, at least that’s what we may be led to believe from reading many online accounts. Seventeen feet may be approximately a quarter wave on 20m, but it is detuned by proximity to the ground. Is it efficient? Well, it’s better than nothing. Without that wire the operator may become the counterpoise – RF gotta go somewhere.

Transceivers can’t count radials

Let’s pretend that transceivers have eyes for a minute. When the transceiver looks at a counterpoise – whether its made of wire radials, or has a callsign – all it really “sees” is a combination of Resistance, Inductance and Capacitance (RLC). Transceivers can’t count radials – you read it here first! Resistance, Inductance and Capacitance are seen as impedance. An efficient set of radials has a low impedance to RF which allows maximum current to flow. So isn’t the current flowing into the counterpoise system really the most important factor in determining its efficiency?

Hams endlessly debate about how many radials make an efficient counterpoise. Is it 4; is it 16, or maybe 128? The debate is pointless unless other factors are also considered. The correct number is just ONE – if your antenna is erected in seawater. I want to propose another number – ZERO and, in the true spirit of scientific endeavor, I have empirical evidence to support my assertion. If an assertion cannot be verified by experiment it just ain’t so.

“I would rather have questions that can’t be answered than answers that can’t be questioned.”
― Richard Feynman

Here is the experiment

The experiment was conducted in the Ham Radio Outside the Box outdoor laboratory (my driveway). A welcome rise in temperature had melted the ice from my concrete driveway and, for once, the Sun was shining. I wanted to test a “de minimis” rapid deployment antenna that would also serve to verify my assertion about counterpoise efficiency.

The initial test was conducted with my 20m emergency wire antenna (a coil-loaded 13ft wire). Instead of radial wires I used my GTU (Ground Tuning Unit).

A GTU is a series connected L-C device. There is a sensor circuit connected to a small analog meter for observing the current passing through the device. The GTU case is a Hammond aluminum box which is electrically connected to the ground side of the GTU. The input to the GTU is a short wire connected to the shield of the coax at the antenna end.

To monitor the current in the radiating element an RF current meter was inserted into the radiator wire. The current meter is basically a GTU without the tuned circuit.

The GTU was placed directly on the concrete driveway; its aluminum box forming a capacitive connection to ground. It would have been more effective to perform the experiment on grass, but my lawn is still buried under a miniature glacier formed by another dreadful winter that isn’t over yet.

The 20m emergency antenna is nominally resonant when a counterpoise is attached so no further tuning was required. The absence of radials required the GTU to do the job of maximizing the current flow on the ground side of the antenna.

At the start of the experiment there was a small current flowing to ground. A similarly small current was observed flowing into the radiator wire (see images). The antenna analyzer recorded an SWR of 13:1.

As the GTU was tuned the ground current increased. It was observed that the current in the radiator also increased. Neither meter was capable of measuring the value of current, so the readings simply represented the relative flow of currents in the counterpoise and radiator. As the ground current peaked the antenna analyzer showed a much improved 1.79:1 SWR.

Quod Erat Demonstrandum?

So did that little semi-scientific experiment prove the point? Well kinda sorta. It established a correlation between ground side current and radiator current. But would it QSO? No, definitely not; it’s just a dumb collection of wire and electronic components – I make the QSOs eh?

Next step – hook up a radio

This is the bit where I boldy went on to risk a radio in pursuance of scientific inquiry. First, the antenna was replaced with my “tactical” 9.5ft whip wearing its finest top hat. The whip was mounted on a small tripod out on the driveway. Even with a googol (10e100) of radials this antenna would not be resonant on the 20m band. That called for deployment of my QROp L-match tuner. The radio called into service for the experiment was my old Yaesu FT-897 set for a blistering 20 watts. Since the antenna is a compromised short vertical my QRP radios were granted liberty for the day. A little muscle was called for to ensure a decent signal could be launched up to the edge of space to pound the ionosphere.

The L-match was adjusted for resonance (X=0 @ 14.113MHz), a low SWR reading on the radio, then the GTU was adjusted to max out the ground current, which lowered the SWR reading on the radio even further. Everything was ready for launch but countdown was paused for one further refinement.

A large plate for pizza?

A GTU is usually used in combination with a capacitance plate laying on the ground. The GTU body is itself a very small capacitance plate, but maybe a larger plate would enhance the ground side current flow. A quick hunt around the Ham Radio Outside the Box HQ turned up a number of options. One of the options was an old pizza pan. It worked – i.e. it raised the ground current a little, but I really couldn’t see carrying a disgusting retired old pizza pan around as part of my portable ops kit. A little further searching resulted in a small piece of what looked like chicken wire. It looked much nicer and it worked even better than the pizza pan.

The final setup – will it QSO?

Do I have to say it again? I make the QSOs not the dumb bits of wire. Well, could I make some contacts with this ZERO radial short vertical antenna system? Here is a picture of the setup.

Once again, a concrete driveway is not the best test of a GTU-based zero radial counterpoise system. The glacial layer of frozen, compressed snow on my lawn may not melt for another few weeks so one has to just make do with whatever nature allows.

I scanned the bands seeking somebody calling CQ and found a station in Connecticut doing a POTA activation. Grabbing my CWMorse paddle key I threw out my callsign and waited to hear if he heard me. Connecticut might be a little close to my QTH in southern Ontario for a vertical antenna with low angle radiation. Anyway, he heard me and sent me a 539 report. I responded with a 579. Contact was made.

A popular mantra among hams is “one is none and two is one” so I figured another contact would hammer a nail in it and seal the proof.

A little more search and pounce revealed another POTA activator in Virginia. Still quite close but my contact there earned my modest setup a 579 report.

Both those contacts were on 20m and I wondered whether another band would also work. I tuned up on 15m but the band was frantically busy with high speed CW traffic and I didn’t want to slow anybody down with my low power into an experimental antenna so I pulled the plug.

So there we have it. A very simple, rapid deployment field portable vertical antenna with zero radials. Now how am I going to make the ladies dance?

Help support HamRadioOutsidetheBox

No “tip-jar”, “buy me a coffee”, Patreon, or Amazon links here. I enjoy my hobby and I enjoy writing about it. If you would like to support this blog please follow/subscribe using the link at the bottom of my home page, or like, comment (links at the bottom of each post), repost or share links to my posts on social media. If you would like to email me directly you will find my email address on my QRZ.com page. Thank you!

The following copyright notice applies to all content on this blog.

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Zero Install es una aplicación de código abierto que nos permite usar otros programas sin necesidad de instalarlos. Parece irónico que esta herramienta tenga un instalador, pero lo cierto es que también permite su ejecución sin instalación previa (zip version) y es un serio candidato para añadir al USB multiusos con apps portables.

Hay que tener claro que no se trata de usar cualquier programa sin instalación, sino que debe Zero Install lanza un listado de aplicaciones de software libre que pueden funcionar de forma muy correcta, por lo que he comprobado.

🍱 Electric Lunch Box for Adults – 90W Portable Heated Lunch Box (3.5L)

Electric Lunch Box for Adults – 90W Portable Heated Lunch Box (3.5L) is a convenient solution for enjoying hot homemade meals anywhere. This portable heated lunch box works with 12V, 24V, and 110V power, makinhome, in the office, in the car, or in a truck.

With its large 3.5L capacity and 2-layer design, you can easily separate different foods such as rice, vegetables, and meat. The 2.5L removable 304 stainless steel container ensures safe and hygienic food storage while also being easy to clean.

The 90W fast heating system warms your food in about 20–30 minutes, so you don’t need a microwave. This makes it an ideal choice for drivers, office workers, construction workers, and travelers who want a warm meal on the go.

✅ View

Disclosure: This post may contain affiliate links. If you purchase through these links, I may earn a small commission at no extra cost to you.