kidphc

WRZP383 · March 4

That laird is pretty short antenna, is it any of it viewable above the basket?

If anything the basket is probably causing some screwy swr and radiation patterns.

Hence, why I have been eyeballing low profile flat racks or just ditching my roof rack on the landcruiser.

From some anecdotal, both by the butt meter and nano vna, testing I did with 1/4 waves and such even when I had a z71 suburban, the big boy roof rack played havoc on shorter antennas.

If they are mag mounts try to keep about 6-10 of roof underneath the antenna and recheck swr. Then bring it closer to the roof rack you should also try making contacts. The roof rack or other accesories close by will give you grief. If you can clear these obstacles you probably will get better performance.

One landcruiser, owner on expedition portal had a rack made. Company became prinsu, but either case he had it made with ears on the back that were also a bit folded. To mount two 1/4 wave antennas. What he failed to mention is that he had to strap (ground straps) parts of the rack to the interior roof to main continuity between the rack and roof (improving his ground plane). The ground plane size and shape can and will affect performance.

In your case I don't think it is a ground plane issue, but more helps to a degree. I believe you are seeing these results due to where the antennas sit in relation to the basket. I also think you should mount them to the hood and double check swr numbers to make sure all is good.

Another note paint types for antennas are really going to matter on the active element more than the ground plane.

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March 2

It means the repeater is for REACT members or they are the primary users of said repeater.

Radio Emergency Associated Communications Team.

Here is a link to a local REACT group near me. In my county they use CERT teams.

https://www.howardcountyreact.org/]https://www.howardcountyreact.org/[/url

https://montgomerycert.org/]

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March 2

Do you guys have a business radio license, much less really need dmr?

I imagining yes, since it is a security team you guys probably also want encryption, which is legal with the business radio license. This radio unfortunately does not have encryption that I can see, so nix that comment.

Being kenwoods they are probably pretty decent.

Maybe lscott can chime in since he is a kenwood fan.

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February 28

It is the one CHP uses (or was going to). They are available, but not necessarily a stocked item. Kenwood will make them in batches though. I know some guys were working on a few things with those lowband decks.

You got a pm.

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February 27

I believe the NX-5600HB now can do P25.
Looking at the XG-100LPA, it was only certified for 16K0F3E per the FCC grant. I did find the manual for it though, and it was an RF sensing.
I see one option is use a MiniCircuits broad band amp that will take the 9mw up to maybe 2 watts then use a Tricom RAMP-25 to put out 25W, but I don't know if anyone has said anything about how to key it, or if it will work with with receive audio.
I've looked a low band (I am interested in at least listening to see what is out there), but in actual application the mobile antenna is going to be huge and narrow banded to be effective.

NX-5600HB Is that the one that was for the CHP? I thought California patrol pulled out of that and Kenwood nixed the project.

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February 27

This is going to be an application that will require coming up with something on your own. You are going to need to design it and build it, or have someone do that. Obviously there was an option for them, and I don't doubt that there were a few factory made units. But those don't seem to be surfacing. Either the few that were purchased are still in use, or they were scrapped instead of making it to the secondary market.
But designing an amplifier for this application shouldn't be all that difficult, at least if you have some sort of accessory connector on the radio that has a keying output for the low band to control the amp. It's going to be a bit more complex than a CB amp due to the requirements for proper biasing of the driver and output transistors for proper linearity due to it being FM and possibly P25 (don't know if the radio does digital modulation on low band. Power output is going to depend on your amplifier design, which will no doubt will need to be multistage since the initial power level being amplified is rather low. But if you design for a 10 dB increase in power per amplifier stage, then it's just how many stages are needed to reach the desired power output level starting with what you have.
The other positive to this is it's low band (30 to 50Mhz). By that I mean that things like the trace length in the circuit board don't really become a factor at those low frequencies. If this were 900Mhz or even 440 to 450Mhz then even the design of the circuit board, trace capacitance and inductance comes into play and needs to be considered for the design. But again, that's not really a factor here.

Thank you. But beyond my current knowledge scope. I have a few guys looking at options. So if we figure it out, I will pass it on.

Unfortunately, there are no p25 low vhf band options.

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February 26

VHF Lo may not be a bad thing, there is 1 itinerant in VHF Lo.......

Tell me if you find a suitable amp.. since that .09 watts of output make it pretty difficult.

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WRUU653 · February 22

I haven't had to. But regularly follow AARL wilderness protocols when out in the woods.

Especially, around George Washington National Park in Wva. Dad lives close by and if you aren't right by a town, you often don't have cell service.

Really wish all radios followed NEMEA standards for GPS data.

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February 22

Depending on where in Florida, you are going to have good to incredible GMRS repeater service.

Personally, I would be looking at no less then a dual bander with dual recieve radios.

The 578 like the 878 are a dual recieve but only have one true transmitter. Which may effect how you would use it. I haven't seen away to unlock the 1000g to do anything but recieve on 2m. Although the amateur version of the radio, I have seen a software/firmware hack opening up the GMRS frequencies. The second problem becomes the antenna, since most dual band/triband radios do a crappy job of trying to do both GMRS and 2m. One of the two has crappy performance, although sometimes JUST acceptable.

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February 22

Which service are you going to use more?

Not that I cadone it, but it is much easier to open GMRS frequencies then the other way around on most radios. Ie CAP modding a ham radio.

Especially, if you are positive you are going to get your ticket again. It's about a 1000x (times) easier now a days since the cw requirement is gone now. Hell might as well get your general. 578 will be great if you are going to get into DMR. They have new model comming out that is essentially a 578 brick where you can option out the blue tooth mic.

Personally, running a FTM400XDR and a Motorola XTL 5000 (UHF). The XTL5K, is going to be replaced with a Harris 100m. So I can retain Gmrs/p25 capabilities on one radio and 2m/70cm with aprs on the other radio. The only real things the Harris brings over the XTL, is VHF and 700/800. The low band VHF amplifier is impossible to find, so that will be receive only.

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gortex2 · February 12

141.3 traditionally was the REACT tone which kinda became the travel tone.

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WSAJ688 · February 9

I should add, I generally use the output tones in my area.

Otherwise, I would be hearing all the kids, lawnscaping companies

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WSAJ688 · February 9

You can do either.

If you are in an heavily used area or have multiple repeaters on the same frequency. Then I would suggest using the output tone. Even then always open squelch (or use monitor) to verify input frequency is not in use, before transmitting.

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Lscott · February 9

Until you have a dozen or so stations doing it on your channel. Then even a short data burst at frequent intervals is going to be irritating.

Oh.. yea I agree. Listen to aprs frequency in a dense area.

What I was referring to was the amount of data that can be sent. Especially, something like FT. Damn symbols rate caps, lol

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February 8

I’d be interested to know what the character limit would be. Depending on the “data mode” it could be enough to send a reasonable message. 1 per 30 seconds isn’t a terrible limitation

Don't know what it is. But a one second date burst is quite small.

Maybe 1/2 of a standard aprs beacon without additional text?

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February 8

Kinda tough.

Data burst can't be longer then one second.

"3) Digital data transmissions must not exceed one second in duration."

Can't have more then one data transmission inside of 30 seconds.

"(4) Digital data transmissions must not be sent more frequently than one digital data transmission within a thirty-second period,"

Data transmissions have to be manually activated. The devices can not store and forward packet modes for data.

Sounds like they don't want you to. Realistically, speaking even an aprs packet is 2.5 seconds long. Ft's' being streams and automated (well kinda), looks like verbiage was put in to stop exactly that kinda of thought.

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February 4

Any antenna even a no groundplane antenna, hate that wording. Will perform better with a ground plane. So depends.

Grounding is for static electricity build up from the antenna and coax. I have antennas in the attic but due to dust blowing over the coax I put arrestor in. For a tremprory install not a necessity but nice. Be aware of this when off roading to a dry dusty area though, especially as winds pick up. No need to fry a radio. Then even an grounding spike would be nice. With that being said a lot of hams on sota/pota (summit/parks on the air) don't even ground.

Personally, for your type of setup. Especially, for solo hill type of excursions. I would build a tape measure yagi ( even though about tv rabbit year yagis, to be multi frequency resonant). Guess it depends on how the mast is secured and what it is. Betcha you it's a harbor freight flag pole, recommend all the time as permanent or portable mast, can't beat the $50 cost.

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AdmiralCochrane · February 4

That's essentially all that I am trying to sort out. I have both this discone as well as a yagi with a perfect 1.0 dip RIGHT at 467.55. I use a repeater about 20 miles out and I can hit it with both types of antenna. The discone comes in a bit fuzzy and the occasional drop out. The yagi hits the repeater full quieting. It's just that I have to physically go out to my mast to rotate the yagi in the various directions that I'm aiming to target. I have a repeater that's actually excellent in my area that I'm fortunate enough to be 2 miles away from, which is where I stick around on mostly and for that my discone hits that rock solid and full quiet..
Additionally, the discone sits atop my mast about 21ft high, and the yagi is further down the same pole only about 12 feet up, and it still gets out 30+ miles fully quiet with about 7.5 watts.
I'm just doing some anecdotal testing of the antennas I have access to. Seeing first hand how antenna design, decibel rating, and lobe patterns really do translate into empirical results. I didn't know much about this end of radio stuff beyond a year ago despite having been involved with it since a young age. Just sort of going down a rabbit hold of antenna gain and the capabilities that can be achieved on the antenna side of things even with low power by paying attention to how things radiate.
I think a lot of people get hung up on sheer wattage power, when your radiation efficiency is a far bigger factor.

What you say is empirical. Unfortunately, a lot of factors come into play.

The theory is just a start. Antenna theory isn't magical, it's physics. So no super bending the laws to get magical more "farz" from similar designs. We give up some here for more there. Unfortunately, advertising from the companies selling us stuff obfuscates a lot of the truth, and the internet adds more.

Same thing with the gear we use. X vs y company. How much it cost vs quality. Does it make a difference? Yes/no. Hard to explain or quantify even in person.

Glad you are testing with things and coming up with your own answers. Knowledge is king.

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February 4

It matters a good bit on VHF and UHF but you desire a more shallow angle. Every bit of RF that is radiated into a wasted direction is inefficiency towards your "fars capability". Good 9db gain omni verticals will squash the radiation donut into a thinner pattern in vertical diameter. My suspicion is that the radiation pattern from this discone is apple-shaped.
For HF, that's fine to shoot your RF up at a high angle for ionospheric reflection. But as we know, UHF is just going out never to return.

I get it. Other designs have similar issues. But let's be truthful here, we aren't going to be talking skip zones often with uhf. For me almost the same guys on 2m or 70cm ssb. Well minus some tropo.

Yagis are another example.. Sadly, they have a crap ton take off angle. Tons of the energy is lost up high and into the ground So much so I was trying to design a workable cubic or quad-cubic antenna, by design they are flatter and tighter in radiation angles.

But since a discone, is considered an omni-directional antenna, it is basically a sphere. So yes, 1/3 of the radiation is up top, is in an undesirable angle. So is up to the lower 1/3.

Basically, don't sweat it too much

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February 4

Yes, the antanna can take the RF input and has perfectly adequate SWR, but my question is what that radiation pattern is like.. If the radiation take off angle is such that an equal about of it is radiating at 1 o'clock upwards as it is 3 o'clock, that's not very good.
my question is if that's the case? Unity gain?

From what I get.

The pattern is close to omni directional radiation pattern like. They will be varying lobe gain values, small fingers.

They harder thing to figure out is gain values for a particular frequency. Reading it is between 1.2-2.3 dbi or so.

The gain problem is only a problem if you are a ham might cause some pain doing the rf exposure studies, that we are required to do now. Which i know really affects hf users more than vhf/uhf/shf/ehf.

Also for these frequencies I not sure take of angle is going to matter especially with an omni directional pattern.

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February 4

You can transmit on discones. Especially, if the swr is acceptable in the transmit range.

They are really optimized for recieve. So mileage would vary. The transmit radiation pattern are often not very good because of this.

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SteveShannon · January 31

So with that being said, what would be the advantage of a yagi with 7Dbi that is directional vs an omnidirectional vertical that is 7Dbi?

Exactly as Wrxb215 said.

Basically, since the cone is narrower then the omni directional antenna's pattern, you can steer the yagi in the direction you want to hear. Effectively nullify any RF interference (ham call it qrm) or noise, well at least lowering the level. If you radio fox hunt generally a yagi, even low gain ones are helpful in pointing you in the direction. They are often coupled with attenuators, you will often see the guys flipping the yagi on the side to attenuate it further. Opposite to the suspects polizaration. To make reception weaker and isolate to a finer degree heading.

Yagis generally have a higher gain level than their vertical/horizontal counterparts due to the squishing of the pattern. You generally switch from length of the antenna space to the swing space a yagi needs. Plus you can stack yagis onto arrays, Which will increase their gain levels.

So comes down to do you need spray gun (coverage) or an ultra fine pinstriping paint brush (detailed control).

Each have their pros and cons.

Just an fyi: the amateur (hams) that are into eme and moon bounce (considered weak signal due to the distance). Use stacked arrays with high gain levels and 1500 or so watts of power. To get as much signal to where they want it instead of scattering it around them.

Same with the guys that work satellite.

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SteveShannon · January 31

We have an owner out here, he has about 6 heavily used repeaters. Equipment for way more.

1. He has the resources.
Ie. Equipment, knowledge and the network of people (for repeater sites locations)

2. It's a hobby for him

Originally it was set up for the Red Cross, as the primary user. He has it open for everyone licensed although it isn't published. We all acknowledge, should the Red Cross need them, we give way.

Some people do it so they can. Some people do it because they feel they are helping the community.

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Lscott · January 31

I like to think of antennas like and adjustable flashlight.

Omni kinda like a donut from the side 3d wise. It would be like having the open without a shroud like a latern.

As you you increase gain. The beam becomes flatter and flatter into a disk.

When you speak of yagis you have put the shroud on and focusing a beam. A beam that shoots more light out the front but spits some out the rear. Hence why yagis have a front to back ratio for gain. There is a technical expectation, and some design that focus more forward? But I am skipping that.

All antennas create lobes so generally, they measure the strongest lobes.

The attached with the donut is omni directional. The phallic looking graph is the yagi.

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January 7

YOu are going to want to put an antenna as high as possible for best performance.
Since you have an HOA and I am going to assume that you have approached them for a variance on their by-laws and failed, the next and most reasonable option is an antenna inside the attic space. This will work reasonably well if you don't have a metal roof. Obviously a metal roof will significantly limit your ability to get RF through it.
Another option is a small dish for TV. But be warned that you will need to research the federal regulations allowing for a small dish or off air antenna for folks that are in an HOA and their by-laws 'limit' that. Due to it being a path for emergency communications, the FCC has mandated small dish and off air antenna's be allowed in all instances. But you are going to need to get copies of those federal regulations in hand and present them to the HOA for review before doing anything else. They will no doubt what to verify it before making a ruling. And depending on the caliber of people running your HOA, they may or may NOT take well to being forced by anyone including the federal government to grant a variance. At the point you basically role up the rules like a newspaper and slap them in the face with it. They WILL crawl up your hind parts and file for a new address in there. They will watch you like a hawk, making sure to enforce EVERY other regulation and by-law they have on the books. And of course fine you as often as is possible until you sell out and move. But it's an option, so I figured I would mention it. After all the HOA isn't going to know what antenna is for what.
But, first option is filing for a variance with them and seeing if you can put up something on an eve of the roof on a small mount.

Forgot about slot antennas.

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