Source: https://forums.mygmrs.com/topic/1174-btech-uhf-amp-with-gmrs/
Timestamp: 2019-04-26 05:38:12
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BTech UHF Amp with GMRS - Technical Discussion - myGMRS.com Forums
This will likely, unintentionally, open a can of worms, but what is the general concencous of using one of BTech’s new UHF amplifiers for use with a Part 95 Type Accepted HT such as the BTech GMRS-V1 (which I’m purchasing next week). I do have their BTech 1.25m (220) amp that I use with my Bridgecom BCH-220 1.25m HT, in addition to a SignaLink USB, and a copper J-Pole. I’m running this as an 1.25m (220) EchoLink node (actually I plan converting it to AllStar eventually). I’m also planning to pick up a BTech Digital UHF amp as well for my DMR radios. I do have a few MMDVM hotspots, but sometimes like to go on the nearest actual DMR repeater, which is going to need this amp. Now. Taking off my “amateur hat” and putting on my “GMRS hat”, I’m left wondering if this BTech UHF would work with the BTech GMRS-V1. Technically, it would as the specifications state that GMRS frequencies will be amplified. Legally, however, is the can of worms. The BTech GMRS-V1 is Part 95 Type Accepted for GMRS, but I don’t believe the amp is. (?). Thoughts?
WRAX891 (Jerry -Parma -OH) likes this
Posted 25 April 2018 - 03:49 AM
The amplifiers are Part 90 certified, but not Part 95; it wouldn't be legal to operate, but it does operate in the GMRS band with GMRS emissions. The FCC has been rather unclear with the use of Part 90 certified equipment by referencing a non-existent section 95.1735, but they are more clear about wanting to keep amplifiers off of Part 95 equipment. It falls under the type-certification gray area, but can generally be considered a "no, don't do this" type of setup. Since it sounds like you have a fixed station instead of a mobile station, that's a few more points towards "no, don't do this."
While it is not specifically covered in Part 95 Subpart E, you may wish to refer to the blanket specifications for all Part 95 Personal Radio Services found in Subpart A:
§95.339 Operation of transmitter with external device causing rule violation prohibited.
No person shall operate any Personal Radio Service transmitter to which an external device or accessory has been added such that operation of the combination results in a violation of the rules.
[If a Part 90 amp is used with a Part 95 transmitter, that may be an implied Rule violation because the amp is not Type Certified specifically for Part 95 use and would not show up on the approved equipment listings.]
As always, it is the responsibility of all licensed operators to follow the letter and spirit of the law. If a question arises about Rules interpretation, call 1-888-225-5322 and ask to speak with a ULS Help Desk Agent.
#4 WRAX891 (Jerry -Parma -OH)
The amplifiers are Part 90 certified, but not Part 95; it wouldn't be legal to operate, but it does operate in the GMRS band with GMRS emissions. The FCC has been rather unclear with the use of Part 90 certified equipment by referencing a non-existent section 95.1735, but they are more clear about wanting to keep amplifiers off of Part 95 equipment. It falls under the type-certification gray area, but can generally be considered a no"
Yeah, it’s like repeaters - most are Part 90 and fall into gray area. (Actual devices designed to be repeaters, that is.) I have a BTech GMRS-V1 now, but still just keeping an eye out on Part 95 mobiles. Likely I’ll be getting two Mobiles at the same time, one for myself, another for family down the road. That was really my main reason for buying a GMRS license anyway...
As i see it, (i am legally blind) the linear will allow you to violate the 5 watt limitation for 1 - 7 gmrs/frs combined channels. The FCC is specific about this. For what its worth the linear works well but at only 32 watts.
#6 WRBL507
Posted 27 January 2019 - 11:07 PM
Well the FCC does allow GMRS repeaters. I have yet to figure nd a single repeater, that is actually not a part 90 device. So from my POV amplifiers are just fine to use with a GMRS radio. The antennas are made to be removable and allow the use of different antenna configurations.
So personally I do believe the FCC does allow the amplifier use. JMHO
The max allowed power that can be used on GMRS frequencies is 50watts. No matter if your using a Ht, a mobile, base, or repeater.
50 watts is max. Midland makes a 40 watt mobile. The only value that an amp would use is to take your HT to 50 watts.
The Btech amp, which will work on GMRS frequencies will only go to 40 watts.
So I think you will be safe!
#7 WRBL507
It’s 50 watts for those channels 15-22 and repeater channels 15-22
#8 WRBL507
These amps are Part 90 Type Accepted. I know, Part 95 is actually required, but how many repeaters are Part 95? I asked this question to Bridgecom and they replied that Part 90 requirements are tighter than Part 95, anyway. I’ve used my amp a few times on channels that allow to to 50W. Not that I was able to make a contact anyway as GMRS is crickets around here. As such, I have a node on a GMRS linked network. If it weren’t for the GMRS network, I would’ve paid $70 to talk to crickets.
#10 WRBL507
Midland does make a 40 watt mobile radio as well as a 15 watt mobile too.
Currently they are the only ones doing so that I am aware of. I could be wrong.
HT radios are all usually 10watts or less no matter what kind of radios they are, vhf/uhf for anyone.
The way I see it, until the FCC specifically state otherwise, I will continue to use my amp when needed.
Usually the FCC won’t make a mandate until problems arise. Personally I don’t see any problems arising. Because the vast majority of GMRS HT’s don’t have antennas that can be removed.
#11 WRAX891 (Jerry -Parma -OH)
I have a Henry 1-5 watts in, 25 watts out amp. Center freq is 464 MHz and rated bandwidth is 10 MHz. Henry doesn't specify 95a type acceptance, at least on their website. But here is what they do state: "Type acceptance: When used with type-accepted exciters - where applicable."
I might end up using it in my repeater. I think I saw a comment on this thread or another one on the site to the effect of there being no point in using an amplifier because most mobiles output at least 25 watts anyway. Well, here's my point in considering its use: duty cycle. The transmitter in my repeater is rated at 25 watts, but only with a 10% transmit duty cycle. This is typical. I'm currently running it at ~12 watts for a higher duty cycle. If I add the amplifier, I could reduce the transmitter power to its minimum of 5 watts while doubling my overall output power. Running that amp at its full rated power is not a problem since Henry rates it at 50% duty cycle in mobile use, and 100 % in repeater use!
I believe it too, because its heat sink is nearly 4 times the size of the sink on my 25 watt radios.
There's another advantage to running an amp, too: I'm using spatial separation instead of a duplexer. With an amp, I can locate the receiver antenna near the repeater and the transmit antenna farther from the repeater. That means the line loss will be mostly on the transmit side. So I can locate the amp out there near the transmit antenna and just increase the exciter power to compensate for the loss.
Kind of a reverse of how the serious VHF/UHF weak signal guys put a preamp at the antenna feedpoint to negate receive line loss.
My reading - and I am neither doctor nor lawyer, and this does not constitute medical or legal advice, or the practice of medicine or law - of the FCC rules leads me to believe that only the exciter is the regulated component, so long as the rest of the mess doesn't cause it to radiate beyond your permissions.
So I guess have one more vote for no problemo so long as you keep it on channels 15-22, and especially keep it out of the interstitials.
Any component attached to the RF chain must comply with the rules. GMRS does not restrict antennas (compare to FRS), but it does restrict output power. Output amplifiers are certainly covered under FCC regs, especially with their use on CBRS.
Earlier, I had overlooked rule 95.337, which explicitly states that any external device that increases the transmit power of a radio voids its type-acceptance and legality of operation under Part 95. That should settle any question of legality here.
( Check 95.339 for additional specifications on this topic. )
No person shall modify any Personal Radio Service transmitter in a way that changes or affects the technical functioning of that transmitter such that operation of the modified transmitter results in a violation of the rules in this part.
If the addition of the amplifier does not result in a violation (e.g. by increasing the output power beyond the legal limit), it does not void type acceptance.
Source: 47 CFR 95.337
95.339 likewise states:
Part 95 does not certify those Part 90 amplifiers because such devices are not legal under Part 95. Type certification specifies the operational parameters of the certified device to make sure the transmit power levels, bandwidth, etc. do not exceed what it has been certified to operate under. Changing those parameters causes the radio to operate outside of its certified parameters, voiding its type certification and authority to operate under Part 95.
Any amplifier which is not aware of the channel it is operating under will violate 95.361©, as the combination of radio and amplifier is capable of operation outside of GMRS's maximum power levels. The use of such transmitter will cause violations of 95.337 and 95.339. All equipment certified on Part 95 stays within the limits of Part 95 under all normal circumstances.
Any device that modifies the RF carrier's modulation (power, deviation, modulated signal contents) before reaching the antenna's feedline, with exception to passive devices such as external filtering, requires Part 95 certification.
Posted 06 February 2019 - 06:08 PM
That's a stretch. Part of your claim might be valid if the transmitter has front-panel selectable power output and the combination of amplifier and the highest front panel selectable power setting results in output power that is over the legal limit.
But, here's the thing: the amp the OP is asking about is only rated to 40 watts max, which is within the legal limit. Also my TK-805D is internally adjustable (as are many radios) to 5 watts output.
Let's take that in another direction, though. Using the TK-805D as an example again, the factory output setting is 25 watts. It is no problem at all to program the 462 MHz and 467 MHz interstitial frequencies into it. The 462 interstitial freqs have a 5 watt limit. The 467 interstitial freqs have a 0.5 watt limit. So how is this radio Part 95 type classified, since it is easy to break the law with it?
The answer is, it is legal as long as it is set up so inadvertent violations cannot occur via pressing the wrong buttons during operation.
Now, that does mean the GMRS-V1 specifically might not be legal with the amp, since it has the interstitial freqs programmed into it. That would be exactly the same as programming those frequencies into a mobile radio, even without the addition of an amplifier.
But to say that it is a violation to use an amplifier on GMRS is a gross and incorrect oversimplification.
WPXM352, Elkhunter521, Ian and 1 other like this
The effect of this rule is that you don't violate rules to begin with. There is no distinct prohibition on attaching a Part 95 approved amplifier to Part 95 exciter/transmitter.
§ 95.339 Operation of transmitter with external device causing rule violation prohibited.
The reality is that a lot of Part 90 equipment is routinely used on Part 95 and the FCC is fully aware of this. It is inevitable that high performance Part 95 equipment will cease to be manufactured. I say inevitable but reality is that the crap being sold as Part 95 by the manufacturers is narrow band and that in itself renders GMRS impotent. Licensees need to choose equipment carefully and petition the FCC to permit certain Part 90 equipment (that meets Part 95 specs) be permissible. At same time, reject manufacturers who see GMRS as FRS on 15 watt steroids.
Elkhunter521, Ian and RCM like this
Posted 09 February 2019 - 06:33 AM