Lscott
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Posts posted by Lscott
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3 hours ago, Guest Visitor said:
Well, I will become a member as soon as my GMRS license is received but I do not see what the yearly fee is anywhere on this site. Secondly there does not seem to be any repeaters in Cookville, TN. There's one 70 miles away of which I might get lucky to hit but you have to get permission to use. Again I haven't a clue of how to do this. The second question is this. If I should chose to put up a cheap inexpensive repeater at my home in a hill can you somehow link repeaters to obtain greater blanket coverage. Personally I wish more people in TN would put these repeater up to cover the entire state since tonados are often and many people are left with nothing when this happens. If there is anyone out there that can answer these question please let me know what can and can't be done, why and how. Thanks
That's something you have to determine for yourself.
I had a similar situation with "radioreference.com". I asked for some opinions here about paying the membership fee. After some helpful comments I decided it might be worth it so I paid for a two year membership. There were some features and data I wanted to use, and could have found elsewhere with a lot more effort, so I'm giving it a try since it did save me time and trouble.
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20 minutes ago, nokones said:
allow, and again, allow "any repeater" does not have to identify if the control and mobile stations identify, as they are supposed to.
So long as those stations are operating under the same license as the owner of the repeater. If not then the repeater must self identify. For a private repeater placed into service for use by a family that's the case above. The problems start when "Open Repeaters" are put into operation.
The logic for the above is easy to figure out.
Any station using the repeater, and operating under the owner's license, when they identify it would be the same ID used if the repeater self identified. So requiring the repeater to self identify using the same call sign would be redundant.
When a station identifying itself under it's own license is not identifying the repeater with the owners ID. Thus the repeater needs to self identify.
This is has all been covered and debated multiple times here. Too many people get hung up on the difference and don't understand the key point and simply spread the wrong advice around further confusing even more users. It doesn't help when the FCC has neglected it's duty to enforce the rules where people mistakenly assume the lack of enforcement as proof they're right, no they are still wrong.
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34 minutes ago, nokones said:
for checking the VSWR reading which the Bird does not do. The Bird is good for only the forward and reflected power checks.
It's done all the time. You will need a calculator with a square root function. Look under the heading in the below link:
"VSWR formula using forward & reflected powers"
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10 hours ago, marcspaz said:
The downside to both the MFJ and Diamond meters I have is that they are rated for a 10% tolerance, which is a lot.
And that is of the full scale reading too! So if the full scale is 20 watts your reading could be in error by up to 2 watts. Trying to measure the output of a 4/5 Watt HT and getting a 2 watt error you don't know if it's the wattmeter or the HT that has the problem.
I think with the Birds you can get a 5 watt slug so when checking low power, like on HT's, and a 5% error rating, you get a pretty accurate reading.
I'm also looking at getting a good Bird wattmeter in good condition with "N" connectors on it. So far everything I've seen used is like $300, for a beat up one, to $400+ for a used one in good condition. Then there is the cost of the slugs, which you end up with a collection of those too, and they aren't that cheap either.
I have a buddy who is a full time radio tech at a local city transportation department. He uses a Telwave. I've never heard him complaint about it, and he uses the crap out of it, field and bench work.
I have a Diawa meter currently and I'm not that impressed with it.
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1 hour ago, WRUE951 said:
I keep my repeater open (no pl's) so it seems to get more traffic than the other 3.. I think the key, if you want traffic on your repeater, leave it open.. (no pl's).
Some people seem to have a hard time grasping the idea of a frequency offset between TX and RX and can't get into their local repeater either.
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21 minutes ago, Sshannon said:
@axorlov, @marcspaz, and @Lscott
Thank you guys! That was a truly interesting exchange on the signal strength meter and modulation types. It made me want to learn more. I knew that each S unit is 6 dB change, but I didn’t realize it was based on an absolute reference uV value, although in hindsight I should have.
It gets a bit more confusing when you include gain antennas in the mix. For example with a simple 1/4 wave antenna lets say your S-meter reads 2 S-units. Then switch over to an antenna with 6db of gain now your S-meter will read 3 S-units. Nothing on the TX end or path changed other than your antenna.
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3 hours ago, marcspaz said:
100% incorrect. S-units define received voltage at the receive front-end. 1 S-unit is equal to 0.20 μV (-121dBm).
Also, a discriminator circuit converts FM signals to AM and extracts the information from the AM envelope. If there isn't enough detected deviation or inconsistent receive of the deviation, the discriminator cannot create a proper AM envelope, thus cannot extract the information.
Ah, a proper FM demodulation circuit includes a limiter stage designed to deliberately remove any amplitude changes, before the discriminator stage, so it response only to the frequency deviation.
For good discriminator performance there has to be sufficient signal amplitude to achieve full limiter action.
https://www.arrl.org/files/file/Technology/tis/info/pdf/8506025.pdf
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Anyway back on topic here. I did an analysis of an antenna system I want to install on my new ride. I had a choice between several different cable types and lengths along with antenna and mount. I wanted a roof rack type mount so the antenna had to be a 1/2 wave type that doesn't require a ground plane.
The goal was to see which combination was the best case compared to what I can get to fit. I have to route the cable around a tail light assembly and it has to be behind the rear hatch. It's a very tight fit for the cable and I'm not into drilling any holes.
I went a bit overboard with the analysis but gives you an idea what things to consider. For example some of the cable loses can be made up, sort of, with a higher gain antenna. That's one of the trade offs you can make.
It looks like what will work is the short coax cable mount, using RG-316 thin coax cable, with an RG-8 mini cable extension. Keeping the mount with the RG-316 coax cable length short makes a difference. The mount using RG-58C is a bit better but the difference wasn't more than a few percent different from the one I think will fit best.
If range was ONLY a function of power then the range change varies as the square-root of the ratio of the powers. I calculated a likely range change based on the square-root of the ratios of power loss/gain between the different configurations.
One point about the cable connectors. They are all RG-8 mini type, including the one on the end of the coax cable used on the mount. It comes with a RG-8 mini to PL-259 adapter. The RG-8 mini adapter is a constant impedance type, the normal PL-259/SO-239 are not, thus there is likely to be little in the way of SWR issues using RG-8 mini through out the system. The adapters are rated up to 2.5GHz and the insertion loses are very low.
Diamond C101 Cable Assembly.pdf Diamond C110 Extension Cable.pdf Diamond K550 Luggage Rack Mount.pdf Mazda 2023 CX-5 Antenna System Analysis Rev 5.pdf SG7500A.pdf Coaxial Cable Attenuation Chart.pdf
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Just a comment here about power verses range. Most of the remarks in general are true in favorable conditions. However where power may be a significant factor is in fringe conditions. I'm not talking about at the limit of operating range. I'm thinking more along the lines of cases where signal attenuation could be high. Examples operating in heavy foliage areas, heavy rain, inside of building with radio wave absorbing materials etc. I don't see much in the way of usage experience mentioned under those conditions.
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15 minutes ago, Rikeman said:
I have way too many radios, to include the BTECH gmrs pro and the wouxun KG935G. As I think others have noted, I can set them side by side both with Nagoya 771G antennas. The wouxun picks up way more traffic. The BTECH does work pretty well and I think the Bluetooth and easy program on the fly make it a worthwhile radio to own. If I really needed one radio I knew I could count on though, this would not be it. The wouxun is hands down the best gmrs I have.
You can never have too many radios. There is always going to be some feature or function you want on your "favorite" radio but doesn't have it. Then you see it on another radio. Soon you start thinking about buying it.
You can spot a radio geek by the number of radios hanging off their belt. Most likely they have more than one.
- DeoVindice, WRUU653 and Sshannon
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1 minute ago, Sshannon said:
Well, the icom brochure lists them as 5 watts for both the UHF and VHF version, even intrinsically safe models. Are you saying that someone might have turned the output down to further reduce the risk potential?
That's possible. Look at the Kenwood NXDN radio brochures attached. These are the radios I have. The IS models show as 5/1 watt. I got two UHF radios from Canada a while back, both were IS models and both had very low output power. The Canadian brochure shows no more than 2 watts for the UHF models, bummer. I had to send both radios to a particular shop that was certified to work on Kenwood IS rated radios. I couldn't send them just anywhere. They set them for the expected 5 watts, for the US market, and still kept their IS rating.
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2 hours ago, Sshannon said:
The FCC ID is AFJ289402. Also these are intrinsically safe radios, which I thought interesting, although I have no need for this.
Be careful of the "intrinsically safe radios" since part of the specifications has the output power reduced for operation in explosive environments in some cases. I've seen nominally rated 4/5 watt radios set for 1, or maybe 2, watts at the most. If that's what the radios are set for then you either need the equipment to re-calibrate them or spend the bucks sending the radios in to a shop. I've been there and done that a couple of times, expensive, $120/hour bench charge minimum, $20 shipping each way and $8 insurance.
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3 minutes ago, Sshannon said:
I’m looking at a pair of Icom F4161DS handheld radios at an auction site. They’re NXDN and I might be interested in playing around with them. I’ve got a three days to decide whether to bid on them or not. Do any of you here have the necessary software?
I would research those radios a bit more. They come in different band splits. Often the seller gets the info wrong. I always try to get the FCC ID and look up the frequency split the radio has the grant just to be sure.
I don't know if the Icom radios will operate outside of the official band split. In your case I would likely go for the 400-470 one. That covers the whole Ham 70cm band, GMRS and most of the commercial band frequencies.
A few other things, make sure you can get the radio to do wide band FM, and most of the older Icom NXDN radios will only do the 6.25KHz digital NXDN protocol. I heard the new Icom radios might do both 12.5KHz and 6.25KHz NXDN. I know all my Kenwood NXDN radios will do both.
As far as software goes I don't have any. You might get a copy from this link. If you haven't registered before you get points for signing up. I think you will get enough to qualify to download the software.
Now if you want to buy it then try this link.
https://www.buytwowayradios.com/icom-cs-f3161-f5061.html
If you do want to bid on the radios make absolutely sure they are NOT password locked!!!! I had that happen with a few Kenwood radios. Fortunately I had the special "engineer" cracked versions of the software that allowed me to bypass the damn read/write passwords used on them. Those were sort of hard to find. One I had to get the cracked software from a source in Mexico of all places.
- Sshannon and wayoverthere
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7 hours ago, WRMS528 said:
Kenwood HT replacement batteries ? Anyone know of a good brand / source for quality replacements? I have several older LMR Kenwood HTs, for which original Kenwood batteries are no longer available. One is a TK-370G. I want good quality, but my biggest concern is safety with Lithium ion batteries. In terms of mitigating any potential fire risk, due to cheap and or unprotected cells. Another question is : is it even OK to use Lithium ion batteries in an older HT , which when the HT was originally manufactured, Lithium ion chemistry was not yet available? I realize if I go with a Lithium ion battery that I would need a new charger, compatible with the Lithium ion chemistry. I see plenty of offerings on Ebay & Amazon, but can't tell about the quality of cells used. Some claim to be made of quality Japanese cells, which would be good. But who knows if what is advertised is so?
Thanks WRMS528 Mike
I've got a few of the TK-270G's and TK-370G's too. I just looked for battery packs on eBay. Make sure the seller has a money back guarantee. The cheapest ones are the KNB-14, but have the least capacity.
Another option is an AA-cell battery holder.
You can then buy some of the Eneloop cells to fill it.
https://www.panasonic.com/global/energy/products/eneloop/en.html
And lastly you can check these guys out. Not the best prices around but have a good selection. I think the KNB-15AH and KNB-15A will work.
https://batteriesamerica.com/collections/land-mobile-radio-kenwood-batteries
https://batteriesamerica.com/collections/land-mobile-radio-kenwood-batteries/products/knb-15a
https://batteriesamerica.com/collections/land-mobile-radio-kenwood-batteries/products/knb-15ah
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10 hours ago, gortex2 said:
I assume it also depends on where the elements are on the dipole. All on one side will throw some RF one way. I have a mix match of them. On VHF I have one with all 4 elements to one side and it helps cover an area and put more gain in that direction. At home I have a single dipole on each bearing (N, E, S, W) so less gain but more omni.
That’s about right. The mounting pole acts as a reflector for the elements giving a bit of directivity to the array when they are all mounted on one side.
If someone is looking at this type of antenna they should keep the above in mind.
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22 minutes ago, Sshannon said:
Very cool, @Lscott! It would be great if the antenna manufacturers all provided EZNEC models of their antennas. I’m thinking it the DB404-B and how the folded dipoles can be rotated on their mast to accomplish exactly what you’ve illustrated.
Yes it would. Another poster, gman1971 I think which I haven't seen posting in a LONG while, talked about putting up a 4-bay vertical. I was curious how it looked from a coverage point of view since he said it was directional. I simulated to see. It does have some directivity but it's not huge.
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On 2/8/2023 at 1:12 PM, WRQI583 said:
Or the owner of the repeater could co-phase a couple of yagi's and get the repeater to keep most of its coverage in the USA instead of running onmi-directional antenna(s).
I tried to simulated a solution like the above but used just two simple vertical dipoles. Since it has to do with antenna modeling, there is another thread on the topic, I put the results there and a link to it here.
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This is part of another thread dealing with the possible access of a US located GMRS repeater by unlicensed GMRS users in Canada. Its another response to the following post.
https://forums.mygmrs.com/topic/5213-cross-boarder-usacanada-gmrs-communications/#comment-52029
This is the repeater in question and the approximate coverage zone.
https://mygmrs.com/repeater/6815
It got me thinking is there a simple way to do it without having to use Yagi antennas. The answer seems to be yes. I'm putting the results here since it really shows how the power of antenna modeling can be used to answer some basic, but important questions, to solve real problems.
The simplest idea is using two "phased" 1//2 wave vertical dipole antennas spaced apart on a boom and rotated to the desired angle. You get a cardioid pattern where the "null", back side of the cardioid, can be place along the US-Canada border while still covering most of the intended targeted US coverage zone. It doesn't reduce the signal to zero but likely enough it won't prove attractive to bother with unless the station is very close by.
The software used here was EZNEC.
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I think that’s where I took my exams years ago.
I was at a local Ham swap this morning and yup I saw one guy with a couple of radios complete with speaker mics hanging over both shoulders.
What are Signal Reports? What is an s-unit? Why does this matter?
in General Discussion
Posted
Writing up technical material isn't easy to do, time consuming and trying to make it understandable takes a good bit of effort.
I've done it at my work place a few times. I can appreciate what goes into it.