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Messages - vwflyer

I wrote a couple of short documents that can be helpful to someone looking into how to use ham radio for emergency communications. I plan to give them to interested people, let them read through them, then answer any questions they have from them. I hope some of you can find them helpful too.
Hi Dylon,
You have a lot of good questions. I'll try to answer of few of them. I'm not an expert but I can pass on what i think I've learned. I give no guarantee of the accuracy of my answers.

It sounds like you have a good setup. I have found my MTR3b to be a great performing little radio and I have found QRP in general to be very effective. I've also used end fed antennas almost exclusively with QRP and they have worked well for me. That being said, QRP is a lot like fishing, if you don't stack the odds in your favor you may get a bite and you may not. Calling in the blind is the least optimum way of securing a QSO. Some days you snag a good one and some days you get nothing. When you are testing out a new antenna or radio it can be disheartening when your first trip out returns only minos. You have a great SOTA setup. If you self spot a SOTA or POTA activation you will stack the odds in your favor by bringing the fish to you. Now you are being chased by others who would have not know you were there or wouldn't have been interested in a contact with you otherwise. I have gone out on consecutive trips outdoors with my MTR and not had one bite. I started to wonder if my setup works. Then I go activate a summit (spotting myself) and in 20 minutes make 30 contacts nationwide using the same setup.

To address some of your questions specifically:
Half wave wire antennas when in free space (or when more than half a wavelength above the ground) radiate mostly broadside. They also radiate off the ends of the wire but not as much. As the wire is lowered below half wavelength to the ground the horizontal radiation pattern turn more and more omnidirectional. A 40 meter half wave antenna only 20 feet off the ground will have a mostly omnidirectional radiation pattern. As for the takeoff angle, it will be quite high and NVIS will work if NVIS conditions exist for 40 meters at the time and location of your activation. Ground losses will not be too high for NVIS if NVIS  is available. I have used NVIS very effectively with 3 watts. Your takeoff angle will be high, as I said earlier, but it will be low enough for a communication range of a few hundred miles in average conditions. I have found midday 40 meters to usually work well between 300 and 600 miles with my end fed antennas and QRP CW.
I think that whenever someone gives an opinion, it is impossible to avoid basing that opinion an many preconceptions. For example, it is stated unequivocally that a heavy radio is disqualified from being a good prepping radio. The assumption is that all preppers are going to be carrying the radio on their backs over great distances and will not have a group of people for distributing loads. Of course there are many prepping scenarios in which this would not be the case. What if I were the radio guy in a group of preppers and they carried all my things and I was only responsible for carrying the radio gear? Or perhaps I intend to prep for a flood in my house due to a hurricane and i don't plan on leaving the house but want a radio that can be submerged and take a beating from the floodwaters if my house is flooded.

Another assumption that seems to be made is that parts for other radios will be more available than parts for this radio in my survival scenario. In most survival scenarios, no radio parts will be available to me for any radio. In the hurricane scenario, only the radio parts I already have safely guarded on the second floor of my home will be available to me when I need them. In most other cases where I don't already have in my personal stock spare parts, it's not as if I can get replacement parts for my Icom off amazon or from a local Radio Shack. So in the end, the only parts I can expect to have in my time of need are those I'm stocking up on now. If I own a KX2 and am not stocking up on new switches, jacks, final transistors, screens, etc. for it now, I'm no better off with one of those than I am an old military rig. For many of us, stocking up on spare parts for our radios doesn't make a lot of sense. We don't know what will go out and individual parts, when bought separately, cost a lot more than the whole. For many of us, the best option is to simply have multiples of the same radio. Two KX2s, two military radios, etc. And in this regard, the military radio has an edge on other options in that two of them is more affordable than two Elecrafts or Icoms.

Finally the complexity assumption. That argument could be made, and is made, for any HF radio. That's why we hams highly discourage preppers from buying an HF rig without having a license to use it and then say that they'll use it in an emergency when it won't be illegal for them to use it without a license. We hams have all gone through the learning curve of using HF radios and know how steep it can be. We can never expect someone who has not trained and practiced with the selected emergency radio to be able to effectively use it in a disaster. This holds true of a KX2, my drop dead simple YouKits HB-1B, or a military radio.

In the end, what makes a good prepping radio for one person and scenario makes a lousy choice for others.

QuoteI always used 10.5V as the minimum for lead-acid, SLA and AGM batteries, but I have no idea if that's 50%...

Hi Gil. 10.5V is considered to be 95% - 100% discharged and the battery is considered completely dead. In fact, for most batteries, anything below about 11.3 volts is thought to cause permanent damage.

I agree Wally. The biggest takeaway here seems to be the reverse of what I've always been told. That in order to get the most life out of one's batteries, both in terms of longevity and max ah delivery, one should only sip the top few percent off of them.

People who use these batteries for off grid living generally do one cycle per day. They charge during the day and discharge at night, to be charged again the following day. What most off grid people want, is to buy the fewest number of batteries per year. So for the batteries on the graph, 50% discharge gives you 700 cycles or almost 2 years of battery life. But in order to discharge one's batteries less, one has to have a bigger battery bank (more batteries). So the question is, when does it start paying off to buy a big battery bank up front and only sip the top 20% off of them and when does it make more sense to buy fewer batteries at a time but buy them more often. According to this graph, you will always pay less overall, the more batteries you buy upfront and sip just the top of them.

Lets say a person needs 100ah per day. Lets say he can buy 100ah batteries for $200 a piece. If he plans to discharge them down to 50% he will need two batteries to meet his demands and they will last him almost 2 years costing him about $200 per year.

Now say he wants to only draw 25% off of them. He will then need twice as many batteries to meet his demand. 4 batteries will run him $800 up front but those batteries will now last him 1900 days/cycles or 5.2 years. So twice as many batteries lasts him well over twice as long when running them all together. $800 / 5.2 = $154 per year, a $46/year savings.

This trend holds true for all values above 50% discharge but not for anything below 50% discharge since the vector of the graph changes abruptly at the 50% point. According the the graph, after 50%. you're no worse off and perhaps even slightly better off discharging the batteries all the way down to 80%.

This is what surprised me. I've always been told the reverse, that you will get most of the batteries maximum life so long as you keep it above 50% and you only start to see rapid drop in longevity when going below 50%.
I was reading this article about AGM batteries and noticed the graph relating to cycles and depth of discharge.

Now what I've always been told is that if a deep cycle battery is discharged bellow 50% you will significantly reduce it's life, ie reduce the number of available cycles. Most plans for how much battery capacity you need figures on discharging down to 50%. So if you calculate that you will need 100ah per day of storage you should buy at least 200ah worth of batteries. This will keep your batteries above that magic 50% number and significantly prolong the life of your batter.

Indeed, the graph does so a sharp change in direction right at that magic 50% mark. But after looking at it for a few minutes, it dawned on me that what the graph is showing is exactly opposite the above premise. To me at least, the graph seems to be saying that the first 50% of your battery is where the number of cycles takes the biggest hit and the second 50% has less impact on the number of cycles available to you.

So I crunched a few quick numbers taken from the graph. If I take a 100ah battery and drain it 50%, I get 50ah out of it per cycle and 700 cycles. 50ah x 700 cycles yields 35,000ah over the life of the battery.
If I only sip 30% off the top I get 30ah per cycle and 1600 cycles. 30 x 1600 is 48,000ah out of the battery during it's life. That's a whopping 52% increase in power harvested over the life of the battery.

On the other hand, if I discharge the battery to where there is only 10% left in it at the end of the day (I'm discharging it by 90%) it still gives me 400 cycles, not that many fewer than only taking 50%. In fact, 90ah x 400 cycles gives me 36,000ah over the life of the battery. That's more than I get when I discharge it down to only 50%.

So the graph is definitely showing that the first 50% of the power taken out of the battery takes the biggest tole on the battery's life. The shallower line means smaller changes in discharge result in larger changes in number of cycles and the steeper line bellow 50% means larger changes in DOD result in smaller changes in number of cycles. If you are going to pull it down to 50%, you are not losing anything to keep on pulling it down to 70%, 80% or even 90%. I wondered if this graph was wrong so I looked for more graphs online and they all say roughly the same thing.

Am I missing something or have I been misled all these years?
Digital Modes / Re: FT8 digital comms mode
August 03, 2018, 08:58:31 PM
Just a quick anecdote about Olivia. Yesterday, my brother and I were trying to have a QSO on 20 meters over 1500 miles using Olivia, 50 watts and low wire antennas. It was tough copy but we were getting between 50 and 90 percent depending on fades. Shortly after the QSO my brother went outside and saw that one support rope for his G5RV had broken and half of the antenna was laying on the ground. Later he commented that he thought that it was odd that the tuner settings were different than usual.
Morse Code / Re: Straight Key Cable
July 20, 2018, 06:02:58 PM
The photo hasn't shown up. Perhaps it needs approved.

I imagine, though, that they are referring to one of these...

I've also taken old earbud cables and use those. Some of them have really small wires inside and so are too fragile but the ones with decent sized interior wire make good key cables.
Antennas / Re: Linked Dipole
June 27, 2018, 10:44:27 AM
Everything is a trade off. If you can handle the size and weight of RG58 you have a bit of an advantage using it over RG174. But it's a personal choice. Many people go to great expense and inconvenience to squeeze every last dB out of their rig. Others say, "with one feedline my radiated power is 4 watts and with the other it's 3.5 watts. If they can't hear me at 3.5, chances are they won't hear me at 4 either".

I will say though, that if you're going to put up with the size and weight of RG58, you might as well switch to RG8X. It's basically the same size and weight as RG58 but with markedly less loss.

You might consider a compromise. Use a length of 58 and a length of 174. Connectors add very little loss if they're clean and tight. You might also want to use zip ties or Velcro ties or tape or something to attach your coax to your mast below the feed point to act as a strain relief to the higher part of the mast where it's too thin to support the weight of all the coax.
Antennas / Re: Linked Dipole
June 25, 2018, 05:17:03 PM
More noise often times simply means you're antenna is more effective.
You defiantly will not regret learning morse code. It's not like buying a computer interface to run FT8 and after a few contacts getting bored of it and regretting the purchase. Learning morse code is a lot more rewarding and even if you eventually bore of it, it will always be useful. It's not a product, it's a skill.

I agree that digital modes like FT8 have limited usefulness to the preppers but that's not their target users. On the other hand, FSQ was designed specifically for emergency comms. Modes like FSQ and Olivia are very handy to the emergency communicator. FSQ can even send messages while the receiving station doesn't have an operator present at the radio.  They perform better than CW. They can send faster and in worse conditions. Their only downside is that they require a computer. This adds weight, complexity, points of failure, and power requirements. If you can afford the additional weight and power requirements they are a good way to go.

I have an IC-706 in my suburban and am setting up a mobile station that can run digital on all HF bands. This mobile station will be able to run digital modes for extended periods of time until I run out of gas. Then the foldable 22 watt panel will allow me to run the station for short intervals.
Antennas / Re: Linked Dipole
June 20, 2018, 01:04:10 PM
Sotabeams makes some good stuff. That looks like a nice balun. If you can set up a wispr beacon it might be a good way of doing direct comparisons of the antennas.
This thread got me thinking though, when was the last time I even heard a QRP station?

Do you do much CW? I'm in the El Paso area and I have regular QSOs with QRPers on CW. I'd estimate that ΒΌ - ⅓ of my CW QSOs are with someone running QRP.
QuoteBut not everybody can afford (learn) it. Although CW seems like a really useful thing to know, I personally prefer talking SSB.

You can afford what you value.
Agreed! Avoid real distress calls!
A simulated emergency call should have some goals to be met to prove that the exercise  was successful though. When organizations like ARES demonstrate their abilities to public service agencies, they have to show the value of the radio by proving that important/life saving communications can reliably be handled by their radios. They do this by transmitting non-important but equally challenging messages. Things like your coordinates are a good test of successful communication since it's something that can easily get messed up in the transmission with all those numbers (number don't have context to help fill in the blanks), and it's something that would likely have to be transmitted in a real crisis. It also involves other survival skills like being able to read a map or use a GPS, so it ties the radio in with the rest of the outing.
And as for simulating a distress call, perhaps you can prearrange a call with a ham you know. Have the scouts provide you with coordinates from a map or gps. Make it vary clear on the air that it's an exercise or simulation and make the information passed benign so that other hams don't get excited by tuning into the middle of the QSO.
If you can set up a 60 or 80 meter wire you can be pretty sure of solid local QRP contacts using NVIS.