Repeater with different inputs and output frequencies

[Dustin89]

Trying to hit a local repeater in my area. I set my radio in my jeep to the input frequency of the repeater and set my handheld to the output frequency, the handheld receives only static. Is something wrong with the repeater or I am doing something wrong?

[Q2BWail]

If you are transmitting from a mobile in your Jeep, operating at, oh I dunno, say 10 watts or more, chances are the handheld radio is being desensed. (Desensitization - The reduction of receiver sensitivity due to overload from a nearby transmitter.) The only cure to operate this way is to move the handheld radio away from the Jeep while transmitting, which probably defeats the purpose of what I think you're trying to accomplish. The further away you get, the better it will sound. The other alternative is to change the mobile radio to a radio that can be programmed for an odd repeater split.

 

 

[Lscott]

Trying to hit a local repeater in my area. I set my radio in my jeep to the input frequency of the repeater and set my handheld to the output frequency, the handheld receives only static. Is something wrong with the repeater or I am doing something wrong?

Sort of a silly question but did you check to see if the repeater requires a PL tone to access? If it does and you don't have one set, or the correct one, the repeater won't do anything.

[Dustin89]

The input has a Pl tone of 141.3 the output says CSU/ no tone.

[tweiss3]

Could you possibly have a tone set for the receive frequency? Midlands won't let you separate send and receive tones.

[JD4x4]

Not to hijack this thread (and I'm a 68 yo. GMRS newb trying to learn), but this is sort of a repeater question I think.
I am setting up my 3 new BaoFeng GT-3TP Mk3's with CHIRP and this thought is coming to mind about the Upper GMRS (repeater) freqs- If you can go 50W on these channels, is that only for the actual repeater (ie. non-handheld unit) or can the handheld go above 5W?

I think I may have answered my own question, but you see where I was going with that? I suppose I cant transmit 8W on the handhelds and call them repeaters ...  ??

[Lscott]

If you can go 50W on these channels, is that only for the actual repeater (ie. non-handheld unit) or can the handheld go above 5W?

 

This is what the FCC has to say about it when the rules were last changed:

 

§ 95.1767 GMRS transmitting power limits. This section contains transmitting power limits for GMRS stations. The

maximum transmitting power depends on which channels are being used and the type of station.

(a) 462/467 MHz main channels. The limits in this paragraph apply to stations transmitting on any of the 462 MHz

main channels or any of the 467 MHz main channels. Each GMRS transmitter type must be capable of operating

within the allowable power range. GMRS licensees are responsible for ensuring that their GMRS stations

operate in compliance with these limits.

(1) The transmitter output power of mobile, repeater and base stations must not exceed 50 Watts.

(2) The transmitter output power of fixed stations must not exceed 15 Watts.

( 462 MHz interstitial channels. The effective radiated power (ERP) of mobile, hand-held portable and base

stations transmitting on the 462 MHz interstitial channels must not exceed 5 Watts.

© 467 MHz interstitial channels. The effective radiated power (ERP) of handheld portable units transmitting on the

467 MHz interstitial channels must not exceed 0.5 Watt. Each GMRS transmitter type capable of transmitting on these

channels must be designed such that the ERP does not exceed 0.5 Watt.

 

[JD4x4]

This is what the FCC has to say about it when the rules were last changed:

 

<snip for readability>

 

Thanks so much for he quick reply @Lscott. 

So (by all means correct me if I understand this wrong, which is likely, lol), the Upper 550 (467.5500 MHz) to Upper 725 (467.7250 MHz) which are typically GMRS Repeater Input channels are not considered either "Main" or "Interstitial". Is that correct?

 

<Edited for clarity, succinctness?>

[Lscott]

Thanks so much for he quick reply @Lscott. 

So (by all means correct me if I understand this wrong, which is likely, lol), the Upper 550 (467.5500 MHz) to Upper 725 (467.7250 MHz) which are typically GMRS Repeater Input channels are not considered either "Main" or "Interstitial". Is that correct?

 

<Edited for clarity, succinctness?>

I believe that is correct. The FCC has them reserved exclusively for repeater inputs.

 

This link is a nice summary.

 

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

 

The link below is the most current version of the Part 95 sections. For GMRS you want subpart E.

 

https://www.ecfr.gov/cgi-bin/text-idx?SID=85a15d2032f9f51fa68cef9b9657e610&mc=true&node=pt47.5.95&rgn=div5

 

I have stuff like this printed out as PDF files, stored on the computer and smart phone along with all my radio operating manuals for easy reference.

[JD4x4]

Thanks again Lscott. That WikiPedia list is better than the one found on hamradio.me, and the last place I would have looked, lol.
In my downtime I also found that ecfr page and made a chart from there in a spreadsheet & printed it as a pdf.

I found the wording vague though when it came to Part E and power. 

 

In §95.1763-"GMRS channels" under (a, b, & c)  they all start with "Only mobile, hand-held portable, ... may transmit .." and under (d) it says "Only hand-held portable units may transmit on these 7 channels", so it looks like handhelds can use all of the channels.

But, (of course there's a 'but') in §95.1767- "GMRS transmitting power limits" under (a) (1) they mention mobile as 50 watts but not specifically handhelds. Then their §95.303 Definitions say "Hand-held portable unit. A physically small mobile station ...". So between 1763 and the defs calling them a small mobile I think I'm going to interpret that a "small" mobile can go up to 50W on the 462 & 467 "Main Channels" (not that I'd want to hold that near my head!), unless I've missed something.  

 

Anyway, thanks again for your help (and patience). I'll attach my chart with the rules & defs in it. If anyone sees that it's bad logic, bad info, I'll remove it.  FCC FRS & GMRS Freqs, Use, and Power.pdf

[Lscott]

Thanks again Lscott. That WikiPedia list is better than the one found on hamradio.me, and the last place I would have looked, lol.

In my downtime I also found that ecfr page and made a chart from there in a spreadsheet & printed it as a pdf.

 

I found the wording vague though when it came to Part E and power. 

 

In §95.1763-"GMRS channels" under (a, b, & c)  they all start with "Only mobile, hand-held portable, ... may transmit .." and under (d) it says "Only hand-held portable units may transmit on these 7 channels", so it looks like handhelds can use all of the channels.

 

But, (of course there's a 'but') in §95.1767- "GMRS transmitting power limits" under (a) (1) they mention mobile as 50 watts but not specifically handhelds. Then their §95.303 Definitions say "Hand-held portable unit. A physically small mobile station ...". So between 1763 and the defs calling them a small mobile I think I'm going to interpret that a "small" mobile can go up to 50W on the 462 & 467 "Main Channels" (not that I'd want to hold that near my head!), unless I've missed something.  

 

Anyway, thanks again for your help (and patience). I'll attach my chart with the rules & defs in it. If anyone sees that it's bad logic, bad info, I'll remove it.   FCC FRS & GMRS Freqs, Use, and Power.pdf

 

That's a nice chart you did.

 

Anyway what you pointed out you'll see elsewhere with the FCC rules where the language isn't clear. There is another area on the forums for FCC rule discussions. If you have further questions that area that would be the place to get answers and a lot of opinions.

[Jones]

Your chart looks correct to me, however keep in mind that the GRMS 50 Watt channels are rated at TPO, or Transmitter Power Output, and the 0.5 and 5 Watt channels are rated at ERP or Effective Radiated Power, which includes antenna system gain or loss in relation to a  half-wave dipole.

 

This is correctly worded in your chart, but to clarify: If you have a mobile radio that puts out 50 Watts on high power, and 3 Watts on low power, and you have an antenna with 6dBd of gain, then your 50 Watt TPO would be around 200 Watts ERP. This is still legal, as the channel is rated for TPO of 50 Watts or less.

 

This same radio on low power of 3 Watts into that same 6dBd gain antenna would calculate to around 12 Watts ERP, so would in fact be NOT legal for use on the 5 Watt ERP rated channels.

 

I know there are a lot of guys out there (myself included) running Kenwoods on "Low Power" at 5 Watts TPO on the interstitial channels, but this would only be legal with a quarter-wave antenna. Also note that a quarter-wave vertical ground-plane antenna IS in fact, a half-wave dipole. and thus has Zero dB of gain or loss compared to a dipole. Remember guys, don't use channels 1-7 with your high-gain antenna screwed onto the NMO mount, and don't use 8-14 at all with a mobile radio.

[JD4x4]

@Lscott, Thanks for your help & the ref to the regs thread.

@Jones, that little subtlety of TPO vs. ERP would have bit me if it was a snake, lol. Thanks! And I've got a lot to learn.