Lscott

This is another model file for a 5/8 wave MURS antenna. In this case there are 4 horizontal ground radials. Beside a series inductive element I need to use a 1/4 transmission line matching section to bring the SWR down to near 1:1 at the design center frequency, that's between the 151 MHz and 154 MHz channel frequencies. Without the transmission line matching section the match isn't that great. Looks like the radials really should be angled downward. I also tried a J-Pole model at MURS too. MURS J-Pole Rev 2.EZ MURS Five-Eights Wave GP - Rev 3.EZ

Antenna modeling takes some intuitive insight. Also have to get a feel for the limitations of the modeling tool(s) as well. The high segment count I used was to keep the feed point and series inductive load located at the bottom of the main vertical element. The 5/8 wave antenna requires a series inductive element to match correctly. The dual band antenna I haven't tried to model yet. One reason is you need multiple elements, at the higher frequency, in series using phasing elements or line sections to get the element currents to line up phase wise. Trying to figure out how to do that with a modeling program will take time and good educated guesses on how to do that and get believable results.

https://www.icomamerica.com/en/products/landmobile/portables/v10mr/default.aspx https://www.icomamerica.com/en/products/landmobile/portables/v3mr/default.aspx

The FCC wants either 6.25KHz bandwidth or the equivalent at some future point in time. When that might happen is anyone's guess. DMR can do the "equivalent" part since it can run two voice streams in a 12.5KHz channel bandwidth. The one attractive part of DMR is the ability to build a repeater without the necessity of using expensive and bulky cavity filters. This is the so-called SFR, single frequency repeater. The hand units would TX, for example, on slot 1 and RX on slot 2. The repeater would RX on slot 1 and TX on slot 2. All of this transpires on the same frequency. To change the repeater frequency simply requires switching to another frequency by all involved users. No cavity filter re-tuning required. I've read many comments about how one mode sounds better that another. Consider that DMR, P25 and NXDN all use the same exact vocoder, the AMBE2+, which can run at two different data rates. When running the same data rate, NXDN has two by the way typically offered by Kenwood radios, any differences likely has more to do with other factors with the radio and not the mode as such. Otherwise they should all sound about the same based on the vocoder itself. Where things get sticky with DMR is when a particular site has no need for the extra voice stream, effectively it goes to waste so you end up with one voice stream occupying a 12.5KHz channel. Unless two separate sites have radios with DCDM, duel capacity direct mode and within range of each other, the radios can't sync to a master time slot signal. You also then have to coordinate between sites who uses which time slot etc. This would just make the job of the frequency coordinator far more difficult. The job of the frequency coordinator is to reduce or eliminate interference between sites by distance and frequency diversity means, just the opposite of what DCDM would require. A true 6.25KHz bandwidth would allow the frequency coordinator more flexibility to assign channels since there would be more of them, physically, due to the narrower bandwidth possible. Not every site out there needs a repeater, the usual source for the master slot timing signal, simplex communications works fine for them. This point is very often overlooked by proponents of DMR.

Try this model file. Five Eights Wave Rev 5.EZ

I just wonder how well it's going to work since the cable/wires are not shielded. The cable/wires go right through in close proximity to the RF power stage. You might have been better off punching a hole in the bottom or side of the face plate and running the cable through there. As a side note I have one of these radios and I'm not impressed with the receiver performance. The radio has poor selectivity in the presence of strong in band signals. A few channels I've had to lockout due to fire paging calls, some from 10+ miles away, showing up on channels I'm sure they really don't operate on. I don't pick these calls up on my other radios. I guess for a $110 CCR ,what I paid, that shouldn't be a big surprise.

Unless the state reserves that format block there isn't isn't anything you can do about it. Contrasted to Ham call plates, at least here in Michigan, you have to show proof of your license before they will issue the plate. The fees are the same as an ordinary plate so you don't pay extra for it. At least I've never noticed if they did charge extra.

There is a wide spectrum of charge controllers. What he needs is very dependent on the particular equipment, batteries and panel array. If the panel array/size is large compared to the battery bank then try to find a charge controller that can be "programmed" to limit charge current, voltage points etc. I have several "good" charge controllers from this company. https://sunforgellc.com/product/gv-5/ My solar panels range in size from as small as 5 watts up to 100 watts. I pick the panel size to match the charge controller and battery pack I want to charge, I have several LiFePO4 types from 3.3AH to 40AH. However the charge controllers I have are not "programmable". So, what is a "good" charge controller in one system design may not be so good in another.

Well in reality it's no for the simple cheap ones. Of course there are some exceptions. The purpose of a charge controller is to terminate the charging phase when the battery reaches the full charge state. Some of the controllers use a "charge algorithm or profile" to controll the charging process based on the battery's terminal voltage. For the simple PWM type charge controllers they effectively connect the solar panel straight to the battery terminals. The resulting terminal voltage is whatever the internal voltage is plus the voltage rise required to overcome the internal resistance at the panel's output current. So if the solar panel can output 10 amps, for example, at 12 VDC, approximate battery terminal voltage under charge, that's what you're going to get. A MPPT by definition will try to push whatever maximum power it can squeeze out of a panel into the battery. I've attached a few of the files I have in my electronic library on solar and wind power. 91069768_WhichsolarchargecontrollerPWM-or-MPPT.pdf GrapeSolar GS-Star-100W.pdf Renogy RNG-100D June 2015.pdf 1518183678_RenogyRNG-50DLatest.pdf Renogy RNG-30D June 2015.pdf 1017403390_DesignandDevelopmentofBatteriesForSolarPhotovoltaicApplications.pdf

One other issue is cops having a problem with "scanners" in vehicles. Some Hams make it a standard practice to turn off their mobile radio if they get pulled over. If the cop sees your radio "scanning" they automatically assume it's a "scanner" not a two-way radio. In some states scanners are prohibited. Having your Ham rig scanning may get you a ticket. In some very rare cases the radio was confiscated requiring a trip to traffic court to get it back. The cops in general have no clue about the exceptions so you'll find Hams that keep a copy of the local/state motor vehicle code with the specific exceptions for Hams in the glove-box.

In fact many radios fail in that area, including some of the better ham gear. The typical short cuts are reducing the drive to the FM modulator to limit the deviation to 2.5KHz, and bumping up the audio gain by a factor of two. The worse part is they still use the same wide band IF filter in the RX path, cost saving, in the radio so you lose the benefit of using the closer channel spacing. The more expensive commercial radios do the same but have two sets of IF filters, one wide and the other narrow, to allow use of the closer channel spacing. After all that's why the FCC mandated narrow band in the first place. Also as some people have noticed even with properly designed narrow band radios there is some range reduction. The attached file goes into some detail on that point. For range you can use the simplified formula: (Range to optical horizon in miles) = (Antenna height above ground in feet) * squareroot(2) This would be for one radio. To get the path do the calculation for each radio and add the distances together. Narrowband vs Wideband.pdf Radio Horizon.pdf

Radios fail from time to time. That's why there are repair shops. Sometimes the repair cost isn't worth it. You can spend less or about the same buying another used radio.

Yup. People forget that hand held radios were never intended for high duty cycle, long winded, communications. Some work better than others in that use case. I've used a few of the palm sized radios where after a few minutes of moderate TX they were getting "uncomfortable" to hold. In the winter time they would make great hand warmers.

0ne area that doesn't get much attention is the charge rate on the battery. I was at a Ham Radio swap a year or so back where one guy was selling emergency power boxes with one or two 7AH sealed lead acid batteries in them and connected up to a 100 watt solar panel. That last bit was scary. One of the often overlooked specification on rechargeable batteries is the max charge rate. On the unambitious 7AH sealed lead acid battery that max charge rate is around 2 to 2.5 amps. Anything higher will likely result in damage to the battery, bubbles in the gel which won't go away, for the older gel-cell, to gas generation, hydrogen and oxygen, which is vented to the air and results in a permanent loss of electrolyte for AGM types. So, for a 2 amp max charge rate, and assuming a 12VDC nominal terminal voltage for a discharged battery, the max usable solar panel power is 24 watts. Your typical solar panel will usually deliver about 70% to 75% of the manufacture's STC rating. So, for 24 watts that works out to a standard panel rating of 32 watts at 75%. Doing the same calculation for 2.5 amps results in a max standard panel rating of 40 watts. You have to check the data sheet for the battery you have to figure out the max safe charge rate. BP7-12.pdf UB1272 F2.pdf

Now that you did some measurements it would be a good idea to include this as part of a radio's review. The problem with hand held radios is the continuing reduction in size. Starting with with the older Motorola brick radios down to the tiny palm sized units which which have to dissipate the same power, the RF power stages haven't changed much in efficiency over the years. The smaller cases, including the radio's metal chassis, and the use of more plastic leaves less area for heat to radiate. These smaller radios have a tendency to heat-up/over-heat far quicker than the larger older designs. There are stories where some users have destroyed their radio from using it at more that a tiny TX duty cycle. The cheaper radios don't have over-temp protection. That's one area where they save money and why they're so cheap.

It might be comical but it's an indication the local police are not as well trained as one would assume. Something as basic and routine as running plates and knowing the format for private, commercial, truck etc. should be number one on the list of skills and proficiency required.

Hum… I wonder if other states have similar issues or is it just particular to California?

I would have though laying on the ground face down, hand cuffed and guns pointed at my head wouldn't have been all that funny given how some cops are trigger happy. If it was me I'd be pissed at their screw-up.

That's sort of strange. Any Ham call plates I've seen from other states were rather distinctive. So in California they have to run the call sign plate through the system differently from other types? That seems weird the system can't figure it out on it's own. I would suspect people are telling BS stories.

The “beat shift” function has nothing to do with signal scrambling. All radios generate internal RF frequencies, from the microprocessors etc. , that can get into the radio’s receiver section. The interfering RF signals are integer multiples of the source. These signals appear as phantom signals, frequently called “birdies”, and may generate rather high signal levels on the radio’s S-meter. What the beat shift does is electronically shifts the frequency the microprocessor runs at so the interfering internal signal is moved off your desired frequency enough to make it undetectable.

Lots of people talk about getting a radio(s) for emergency communications. During hurricane Ian how many really needed their radio equipment verses cell phones?

I thought about the vanity plate idea. Chances are almost nobody would have a clue that the sequence of 4 letters followed by three numbers is an FCC radio call sign unless you were involve with radio communications. Anyway I've had a Ham call sign plate on my vehicles for over 20 years. So far no problems. If one were really that worried then why use your call sign on the air? Lot of people own scanners out there.

That's not as cool as the license plate. I once had a car with some kids in it asking me at a traffic light what the letters and numbers mean on the plate. They were trying to figure out what it said. I told them it was a radio station call sign ID.

I'm purchasing a new vehicle shortly and will transfer my Ham call sign plate from the old ride to the new one. It got me thinking about call sign license plates. I'm guessing one can get a Ham call sign license plate, they typically are distinctly marked as "Amateur Radio" etc., for any state they live in. In Michigan they are treated like a normal plate, not an expensive vanity plate, as far as fees are concerned. To get one all I had to do was show my official FCC license to the Secretary of State. What I'm puzzled by is why no GMRS call sign license plates? It's a licensed service like Ham with an official FCC issued call sign unique to an individual.