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4-5w GMRS Certified Radio?


Guest Dave
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New one to add to the list:

 

Wouxun KG-UV9G (8w)

Midland GXT1000 (5w)
Tera TR-505 (4w)
Garmin Rino 700 (5w)

Wouxun KG-805 (4w)

 

One more option for "out of the box" GMRS with more power.  Yay!

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New one to add to the list:

 

Wouxun KG-UV9G (8w)

Midland GXT1000 (5w)

Tera TR-505 (4w)

Garmin Rino 700 (5w)

Wouxun KG-805 (4w)

 

One more option for "out of the box" GMRS with more power.  Yay!

 

 

The most recent FCC report I saw on the Midland GXT1000 series was 2.65 W max, despite their advertising. A bit disappointing, that, but it's still plenty for my needs.

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The most recent FCC report I saw on the Midland GXT1000 series was 2.65 W max, despite their advertising. A bit disappointing, that, but it's still plenty for my needs.

 

I have the Midland GTX1000 and have found them to be a very nice little radio. I originally bought the Motorola MR350R, and found them to be very bad. They had very poor sound quality, and one of the handsets exhibited the low volume issue some of them had. We then bought the Midlands to test side by side, and the Midland outperformed the Motorola in every way, including range. The best part was we could actually hear each other on them. 

 

Later we bought the Tera 505 handhelds and generally use those. We still use the Midlands though, they work well, and are durable. I don't feel unduly worried about them when using them in bad conditions either. 

 

I wouldn't mind buying the Wouxuns though, since I believe they are not a "radio on chip" design, so they should receive better than radios with the radio on chip design.

 

 

 
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I wouldn't mind buying the Wouxuns though, since I believe they are not a "radio on chip" design, so they should receive better than radios with the radio on chip design.

 

If you can find the detailed specifications for the radio look at the receiver section. If the type is stated as “direct conversion” the odds are very high it’s a cheap “radio on a chip” type design.

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If you can find the detailed specifications for the radio look at the receiver section. If the type is stated as “direct conversion” the odds are very high it’s a cheap “radio on a chip” type design.

 

It seems that www.buytwowayradios.com claims it is not radio on chip. 

 

""Classic" Radio Circuitry. One of the big reasons that there are so many low priced radios available is that there single microchips available that control almost all radio features. This is great if you're looking to keep costs down, but there's a reason that popular business radio brands don't use them: they compromise quality for price. If we were going to call our radio "Business Quality" it needed to be built like a business radio - inside and out."

 

https://www.buytwowayradios.com/blog/2019/12/introducing-the-wouxun-kg-805-professional-gmrs-and-murs-radios.html

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It seems that www.buytwowayradios.com claims it is not radio on chip. 

 

""Classic" Radio Circuitry. One of the big reasons that there are so many low priced radios available is that there single microchips available that control almost all radio features. This is great if you're looking to keep costs down, but there's a reason that popular business radio brands don't use them: they compromise quality for price. If we were going to call our radio "Business Quality" it needed to be built like a business radio - inside and out."

 

https://www.buytwowayradios.com/blog/2019/12/introducing-the-wouxun-kg-805-professional-gmrs-and-murs-radios.html

That could be the case. You can see the FCC data on the radio at this site below:

 

https://fccid.io/WVTWOUXUN16

 

The FCC certification grant is there. More of interest you can find internal photos of the radio. After looking I didn’t see the typical radio-a-chip device, which seems to be the favorite used in the cheap Chinese radios, on the circuit boards. I didn’t try to look up the chip numbers so the manufacturer could still be using a different one, or a customized version.

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For the more technically inclined people you can investigate a design by looking at either the schematic, in this case it's not available on the FCC website, or the internal photos, which is better than nothing. 

 

https://fccid.io/WVTWOUXUN16/Internal-Photos/Int-Photos-4695706.pdf

 

Looking at the PCB photos you will notice a large white rectangular part with "C50F" stamped on it. I've seen these before. They are commonly used ceramic filters. In this case doing a bit of searching you will find a data sheet for it here.

 

http://www.quartz1.com/downloads/Tecdoc/filtr_ceramic/LTWC450F.pdf

 

Take a look at page 4 of the datasheet figure 1. You will see the manufacture's marking looks like the one in the photos.

 

As suspected it's a simple 455KHz IF, intermediate frequency, ceramic filter typically used in a Superheterodyne receiver designs. This would not be something expected in a typical "radio-on-a-chip" design.

 

One thing to note in the spec sheet is the 50dB bandwidth spec of just 12KHz. Considering GMRS has a bandwidth of around 16KHz the filter is a bit narrow. However for narrow band, think FRS, the bandwidth is only 11 KHz it would be a bit too wide. I suspect the designers picked this part as a compromise where they tried to get away with using just one filter in place of the two that should have been used to save money. I think some of the commercial radio designs use two different filters for the two bandwidths. One reason why they tend to work better and cost more.

 

And right next to it is a chip "AA32416" which appears to be the FM detector chip which would make sense.

 

https://www.digchip.com/datasheets/parts/datasheet/849/AA32416-pdf.php

 

Radio internal photos.

 

https://fccid.io/WVTWOUXUN16/Internal-Photos/Int-Photos-4695706.pdf

 

And for those who wonder what a Superheterodyne receiver is there is a nice history and write up here.

 

https://en.wikipedia.org/wiki/Superheterodyne_receiver

 

Looking up the numbers for the other chips, assuming they are not proprietary part numbers for the end user, one might gleam some other interesting details about the radio and it's likely performance.

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One thing to note in the spec sheet is the 50dB bandwidth spec of just 12KHz.

 

Notice the plus/minus symbol right in front of that 12KHz rating... that means the bandwidth is +12 and - 12 from the center zero point of 450KHz.  That's 24KHz total Bandwidth.

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Notice the plus/minus symbol right in front of that 12KHz rating... that means the bandwidth is +12 and - 12 from the center zero point of 450KHz.  That's 24KHz total Bandwidth.

Thanks. I missed that. I guess that's what I get for not looking a bit more carefully and just doing a quick scan through the datasheet and dashing off a post. I'm happy to see somebody is interested in the topic enough to look. 8-)

 

So that now brings up the flip side question. Is the bandwidth now too wide? If it's 24KHz then it's way too wide for narrow band FM at 11 KHz. Now it's the reverse of what I wrote in error. Now the normal FM mode is likely OK but not the narrow band mode. Oh well.

 

The FM deviation set for 2.5KHz and the audio gain increased, necessary in narrow band mode using the wide band filter to compensate, will work but the selectivity would suck. Since GMRS is 5KHz deviation narrow band performance likely isn't a big concern.

 

One thing I didn't point out is the power output on the FRS only channels is 0.283 watts as shown in the grant. The FCC allows up to 0.5 watts so this radio won't even do the max allowed output power for those channels.

 

If a potential user is looking at the radio with the idea they may need the narrow band selectivity and the max allowed power on channels 8 to 14, because of a need to communicate with FRS users, may want to consider another radio.

 

In any case looking at the electrical design reveals an aspect of the radio's likely real world performance that isn't mentioned by the manufacture.  At least for the GMRS specific version of the radio.

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I own a couple of the KG-805G and currently considering getting more. My take on the .283 watts is that it has to do with the FCC requirement for no more that .5w ERP, not .5w transmitter output power. If the radio did output .5w, then putting a good external antenna on the radio would cause it to the exceed the max ERP rating for channels 8-14. FCC clearly wants these channels left for close-in communications only.

 

Audio quality is fantastic; quality on par with the best audio I hear on repeaters nearest to me and even better than some, plus noticeably better than the 8-10 year old Midland GXT1000 radios I like so much. (BTW, my GXT1000 are the original 5w versions)

 

 

...

One thing I didn't point out is the power output on the FRS only channels is 0.283 watts as shown in the grant. The FCC allows up to 0.5 watts so this radio won't even do the max allowed output power for those channels...

Sent from my iPad using Tapatalk

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I own a couple of the KG-805G and currently considering getting more. My take on the .283 watts is that it has to do with the FCC requirement for no more that .5w ERP, not .5w transmitter output power. If the radio did output .5w, then putting a good external antenna on the radio would cause it to the exceed the max ERP rating for channels 8-14. FCC clearly wants these channels left for close-in communications only.

 

 

The usual rubber duck antennas, stubby antennas, have a negative gain. To get the 0.5 watt ERP the radio would have to produce more than 0.5 watts. Clearly the market for the radio is GMRS.

 

The low power narrow band channels are an afterthought looking at what components were used. The point is anyone who is considering this radio with the idea of using it to talk to FRS radios, or have a real need too, will likely be disappointed.

 

If the radio does what you want that's what counts. At least people know a bit more about the radio's likely performance and can make a better informed choice. That was the goal here.

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Lscott, I agree with you on the rubber duck having negative gain. However, I still think that because that antenna can be replaced with one that has substantially higher gain then it becomes possible for ERP limits to be exceeded. And since for channels 8-14 the spec is max ERP, that might be why TX power is set so low.

 

Oddly, I have yet to use channels 8-14 for any purpose on these radios yet. I can check them against a couple of different brands/models of FRS to see if there is any notable distance difference.

 

 

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Lscott, I agree with you on the rubber duck having negative gain. However, I still think that because that antenna can be replaced with one that has substantially higher gain then it becomes possible for ERP limits to be exceeded. And since for channels 8-14 the spec is max ERP, that might be why TX power is set so low.

 

Logically I can't see how limiting the output power will prevent exceeding the FCC's ERP limit. Since they have no idea what antenna is going to be attached it's impossible to set a power level that will not violate the rules, unless it's set at zero.

 

You don't even need to attach a gain antenna. A few people have built a corner reflector and just stuck the radio at the right point which results in a higher ERP than what you get out of the radio, even with a fixed mount antenna. The radio is place at the position where the dipole element would go. Then ran a external headset with a conveniently long wire to the accessory input jack on the radio.

 

https://www.qsl.net/ve3rgw/corner.html

 

While not exactly portable its been done for point to point communications.

 

 

 

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Logically I can't see how limiting the output power will prevent exceeding the FCC's ERP limit. Since they have no idea what antenna is going to be attached it's impossible to set a power level that will not violate the rules, unless it's set at zero.

 

You don't even need to attach a gain antenna. A few people have built a corner reflector and just stuck the radio at the right point which results in a higher ERP than what you get out of the radio, ...

Not to be (too) picky. But, I am pretty sure ERP is measured at the antenna and would therefore not include any external reflectors, etc.

 

The FCC defines ERP as the product of the power supplied to the antenna and the antenna gain (when the power and gain are represented in linear terms).

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Not to be (too) picky. But, I am pretty sure ERP is measured at the antenna and would therefore not include any external reflectors, etc.

 

 

So by that definition even a high gain Yagi really wouldn't be violating the rules. There is only one driven element (antenna) everything else is either a director or reflector element.

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On closer inspection the ERP is based on the field strength of the signal. That's the point people seem to miss. A gain antenna increases the "E-Field", Volts per meter. When the tests are performed the location of the field strength meter has to be specified. 

 

When doing antenna testing on an antenna test range the "E-Field" is measured at various points around the antenna. There are relationships that you can use to calculate power (ERP) based on the "E-Field" strength.

 

  https://en.wikipedia.org/wiki/Surface_power_density

 

The references below gives a bit more info on how the "E-Field" in Volts/Meter works out to power. Note that a number for the antenna gain is part of the calculations.

 

http://www.bccdc.ca/resource-gallery/Documents/Guidelines and Forms/Guidelines and Manuals/EH/EH/Section2Final06062013.pdf

 

http://www.parc.org.za/publications/=Field strength vs radiated power.pdf

 

https://en.wikipedia.org/wiki/Effective_radiated_power

 

There are two ways of looking at this EIRP, effective isotropic radiated power, and ERP, effective radiated power. The two are not the same. For EIRP it's assume the power is spread uniformly over a sphere, which will only happen using a "theatrical" isotropic antenna.  The other, ERP,  acknowledges that real antennas have some directional properties, thus a higher "E-Field" in some directions verses others. When the "E-Field" is measured then power calculated you will most likely end up with a power higher than what you see at the transmitter's output. That's the antenna's gain.    

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Dang!! This form's software keeps screwing with the URL's, they won't post right. They cut and past OK but when I post the message they get trashed. I'll try one more time.

 

"https://www.google.com/search?q=field+strength+versus+power&client=firefox-b-1-e&ei=WsY6X4GYI8-PtAaf9JOAAw&start=10&sa=N"

 

"http://www.bccdc.ca/resource-gallery/Documents/Guidelines and Forms/Guidelines and Manuals/EH/EH/Section2Final06062013.pdf"

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Well the only way to get this to work is copy the whole URL into the address window up to the ".pdf" part. Then substitute the following for the "...ents" part. Then it should work for the long one.

 

resource-gallery/Documents

 

For the shorter one copy the whole URL into the address window up to the ".pdf" part. Then substitute the following for the "....ications" part. Then it should work for the short one. Don't miss the leading period.

 

.za/publications

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I have experienced the URL pasting issues in the past too. When I do have such an issue I past the URL in text editor, add quotes around it and then just pasted the quoted text. Quoted text often times prevents the automatic hyper linking. A pain? Yes! But sometimes necessary.

 

 

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