axorlov
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Posts posted by axorlov
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1 hour ago, WRPD719 said:
I live about 200' above grade in a high rise
There is no practical way to ground to the soil, but that's ok. Important is to have all your radio equipment grounded to the same ground bus. Your radio, power supply, etc will be at the same "ground" potential, which will be different from the real ground potential. But it is not a big deal. And connect this grounding bus to the building ground, to keep AC protection, as code requires.
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What's important to understand, there are two types of the ground: DC ground and RF ground.
Our normal mains electric supply is at 60 Hz AC, with wavelength of around 3 million miles (my napkin math may be bit wrong, but it still in millions), so, any length of ground wire in your house do not produce any wave effects on your mains electricity. It's all like a direct and immediate short circuit, no matter how long it is. In a normal house. This is why it is safe to call your mains ground a DC ground, even if it is for 60 Hz AC.
RF ground is different. When we start to talk about tens of feet of ground wire, that's be tens of wavelengths on 462 MHz (the wavelength is about 65cm or 26 inches), with all kind of wave effects you may expect, reflection, diffraction, resonance, etc. There is also a skin effect, when the higher the frequency, the closer to the surface of the wire current flows.
So, in my view, there is no difference between 60ft and 30ft of ground wire. Both will pick up RFI at all VHF and UHF wavelength. It's better to avoid ground loops, if possible. If antenna is outside, it's better to run separate ground wire to the grounding rod to protect from the static. But if the antenna is inside, protected by the house from static accumulation or from the lightning, no reason to create elaborate protection. I think you'll be fine without grounding the antenna.
With regards to if to ground to the mains ground: yes of course. Ground your station to the mains ground at the panel or at the dedicated grounding rod, connected to the mains ground. Idea is that you have a single point of ground near your station, that is connected to the ground somehow. And to that point you connect your radio ground and our antenna ground, and your antenna switch ground, and your amplifier ground, etc.
I use a flattened 1/2" copper pipe, about 10" long, bolted to the back of my desk, with ground screws taped into it and connected to the radios and power supply. This grounding bus is connected to the rod in the soil via 4ga stranded copper wire about 10ft long (I'm on the ground floor and can drill walls). The rod is connected to the other rod and the electric panel via 4ga solid copper wire outside of the house.
If you do not have an option to run short (relatively short) grounding wire from your station to the ground, you should still have a connection to the mains ground, to be protected from AC faults, and because it's prescribed by the code and common sense.
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The short version: If the antenna and cable are inside the house, you should not ground the antenna.
The TLDR version: Using a separate ground path to the antenna creates a "ground loop", and the bigger it is (in sq ft), the more RFI it will catch and put up your radio's front end. Since you are not concerned about atmospheric static accumulation, do not bother with grounding the antenna. Whatever static may accumulate, will be dissolved via the cable shield through the grounding of your radio.
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Looking at some reports and some photos, there are Baofengs in use, by Territorial Defense Units. It's basically a "well regulated militia" formed from volunteers, often with combat experience. They are organized as a light infantry, without any IFVs or heavy infantry armaments. Only small arms, light machine guns. RPG-7, RPG-18 at max, and these are not fielded everywhere. Equipment other than weaponry (helmets, vests, uniform, sleeping bags, night vision, etc) is mostly supplied by volunteer efforts and donations. Units are under the command of the military and sometimes headed by actual officers. Baofengs seem to be bought off public donations.
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TK-780H-1 is a VHF radio, as was pointed out above. Not going to work for GMRS.
Both TK-880(UHF) and TK-780(VHF) use the same software, KPG49D, and the same cable. Chirp does not work with TK-780 (and TK-880).
To allow front panel programming (FPP):
- with V1 version of the radio: FPP must be enabled from the KPG49D;
- with V2 version of the radio: the resistor has to be removed, and FPP must be enabled from the KPG49D.More info in this thread:
To determine if you have V1 or V2, you look at the rear label. If it says "Ver 2.0" you have the version two. If it does not say anything related to the version, you have version 1. Check this thread:
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In a big picture, $35 is only what, 6 big macs? I can easily save it not having breakfast for a week. Taking in account how much money ham gear costs, it's nothing. But it is a historical precedence, I think Ham license was always free in US, no? Not counting the testing fees.
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Another example of two TK-3170 talking to each other. Note, there is no line of sight. I was walking on the shore trail from NW toward SE. Trail is low, near the water and follows all landscape features. Friend was walking on the same trail toward NE, descended from the point on the E down to the water. We had communications broken only few times, when either me or my friend were deep in the shore canyons. There was never a direct line of sight between the radios. But thanks for the reflection and refraction of the 462MHz in mountainous terrain communications were reliable for the most part of the travel.
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Red lines are two DLR-1060 talking to each other, blue lines are two TK-3170 talking to each other. Test was done at the same time: I was riding bicycle with DLR and TK in my bag, while friend was sitting at the picnic table in the park. Table is located in some sort of depression, about 5", so the result on the flat ground could be better. The housing situation on the north and on the east are dense. There are small lots, 4000-6000 sq ft, not bigger. Housing is one- and two-story. Some two-story multi unit apartments.
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RBC-450 with or without spring are mobile half-wave antennas not requiring ground plane. Good for the intended application, imo.
Base antennas like FG-4500 will fail quickly on a vehicle. They are rated for 100+mph winds, but not for all-day.
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Since you have the roof real estate used up with good stuff (boats, panels, who knows what), I'd say half-wave antenna at any convenient location (front corner on self-fabricated gutter mount) will do.
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I was following the developments since 2014 annexation of Crimea and flare-up in Donbass region. Ukrainian political body and army brass decided to put money in second hand US Army equipment. It's mostly Harris, as far as I can see (my horizon is limited). By now they have robust and protected communications all the way down to platoon level. Disadvantage is that US can listen on them, being holder of the encryption keys and provider of the hardware. Advantage is that they are in the war with the country other than US. This decision was derided by some UA politicians at the time from the monetary standpoint, but it clearly has payed off. We see plenty of intercepts of RU forces comms, while we have exactly 0 intercepts of UA comms. Of course, not everything is published and will be published, but the ratio is kind of clear: (big value)/(negligibly small if not 0).
On the other hand, Russia is being Russia started the war with a false assumption that they will be greeted with flowers. Sure, flowers will go on the graves of the soldiers. The second link has a picture of R123, that I'm more intimately familiar than I would ever liked to be. That's a technology from the late 60-s, with vacuum tubes and everything that implies. Russian forces use open comms over shortwave to coordinate transport and logistics and other stuff. Just google it, you will quickly find the freqs.
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I have Diamond X50NA (with N connector) on metal mast 17 feet up from my roof. 7 feet below the X50 there is a TV yagi antenna. Mast is grounded, and shield of the LMR400 is also grounded. My SWR is 1.9 on 462MHz. I also did a quick dirty experiment for the common mode current on the shield: measure SWR when holding cable connector in my hand and when not touching it. Both measurements were 1.9, which indicates none or negligible common mode current.
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10 hours ago, MichaelLAX said:
Since my TYT-UV88 has TONE SCAN but does not have a REVERSE function, I have programmed all 8 repeater channels into another 8 channels in reverse, for when I take my road trips to look for repeaters and/or track down repeaters.
I expected you to pop up with something like quoted above. You, the Fearsome Hunter of Repeater Users, the Sneaky Decoder of Input Tones.
- MichaelLAX and marcspaz
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Resolute and affirmative YES. But not with metallic paints. Just any black primer or matte no frills paint will do. Your goal is to hide it from HOA, correct? Not so odd question.
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C'mon Marc, would you program 467.xxx0 into your scanner for the road trip?
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I agree with Lscott, while 467.xxx0 MHz are channels, in a context of what we are talking about, they are not in the picture. And the 467.xxx5 MHz with it's 0.5W max power are rather useless when mobile on the road, so only 15 channels may have any real use.
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Results are expected: half-wave antenna performed better in a situation with questionable or non-existing ground plane. I would go with half-wave. SWR is better, efficiency is better, that was confirmed by test in the field. Half-wave antennas do not require ground plane and [almost] not affected if you have a ground plane nearby. But if you are satisfied with quarter-wave, it's all good.
With regards to quarter-wave vs half-wave for power and efficiency: quarter-wave with good ground plane is identical to half-wave with no ground plane.
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FG4500 (and similar) are not good for car because of wind resistance. These kind of antennas are often rated for around 100mph. And when installed on a mast, rarely they see hurricane-level of wind, certainly not every day.
It could be useful, if mounted on collapsible mast 30' or higher, connected to this Retevis repeater, when stationary.
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Channel 16 is 462.575 MHz, shared with FRS and legal to use for whatever by anyone, if done in accordance with FRS rules with FRS-certified handheld.
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18 hours ago, ABTOCMEPTb said:
I want to use fg4500 on the move with RT97 repeater placed inside the car.
Yeah, I'm wondering too. 50W mobile with antenna on the roof already in. What is the problem are you trying to solve with low-power repeater and low-mount antenna (bull bars, mirrors)? And while on the move?
Yagi beam spread
in Technical Discussion
Posted
Hard (impossible) to say in advance. Experiment and tell us! Something as simple as this may be the answer: https://www.ebay.com/itm/372242500835?epid=2256171885&hash=item56ab61cce3:g:jm8AAOSw0o5aoGy4