Difference in ability to TX and RX on base station

[Whiskey363]

I have a KG 1000 with Tram 6.5 dBd gain fiberglass antenna mounted on a 10 foot steel pole to my chimney, (15 foot high total.) I'm running 75 feet of Messi & Paoloni Ultraflex 7 Premium coax, and at 50 watts I'm reading 1.8 SWR. 

I can easily hear people talking on a repeater that is 13.79 miles away straight line distance ( granted permission to use.) I am certain I have the correct input tone, but no one can hear me at all.

(They are asking if anyone is waiting to jump in so I'm confident they are not ignoring me.) 

My question is, with 50 watts of transmit power, if I can clearly hear them, should they not be able to receive my transmission?

Edited Thursday at 02:44 PM by Whiskey363
Not line of sight, straight line distance

[SteveShannon]

Just now, Whiskey363 said:

I have a KG 1000 with Tram 6.5 dBd gain fiberglass antenna mounted on a 10 foot steel pole to my chimney, (15 foot high total.) I'm running 75 feet of Messi & Paoloni Ultraflex 7 Premium coax, and at 50 watts I'm reading 1.8 SWR. 

I can easily hear people talking on a repeater that is 13.79 miles away line of sight ( granted permission to use.) I am certain I have the correct input tone, but no one can hear me at all.

(They are asking if anyone is waiting to jump in so I'm confident they are not ignoring me.) 

My question is, with 50 watts of transmit power, if I can clearly hear them, should they not be able to receive my transmission?

75 feet of UF 7 is definitely costing you some power, but are you certain you’re transmitting on a repeater channel?  You’ll hear the repeater on both a simplex channel and a repeater channel, but only the repeater channel transmits on the correct frequency in the 467 MHz main channels. 

[Whiskey363]

16 minutes ago, SteveShannon said:

75 feet of UF 7 is definitely costing you some power, but are you certain you’re transmitting on a repeater channel?  You’ll hear the repeater on both a simplex channel and a repeater channel, but only the repeater channel transmits on the correct frequency in the 467 MHz main channels. 

Being new to this I could quite possibly be doing something wrong. I was scanning channels and picked up the conversation on repeater 21.  I used the Wouxun software to program the repeater name and frequencies as RX 462.7000, TX 467.7000 with input tone.

[MarkInTampa]

15 minutes ago, Whiskey363 said:

Being new to this I could quite possibly be doing something wrong. I was scanning channels and picked up the conversation on repeater 21.  I used the Wouxun software to program the repeater name and frequencies as RX 462.7000, TX 467.7000 with input tone.

You should have tone on output of 467.700 not the input. The input tone of the repeater is the output tone of your radio.

[SteveShannon]

11 minutes ago, Whiskey363 said:

Being new to this I could quite possibly be doing something wrong. I was scanning channels and picked up the conversation on repeater 21.  I used the Wouxun software to program the repeater name and frequencies as RX 462.7000, TX 467.7000 with input tone.

So channel 21 is a simplex channel that transmits on 462.700 MHz.  Channel 29 (aka RP21 or something like that) is the repeater channel that automatically transmits on the correct 467.700 MHz frequency.

Try just changing to the repeater channel and setting the repeater input tone there.

[Whiskey363]

10 minutes ago, MarkInTampa said:

You should have tone on output of 467.700 not the input. The input tone of the repeater is the output tone of your radio.

Thank you!

[Whiskey363]

9 minutes ago, SteveShannon said:

So channel 21 is a simplex channel that transmits on 462.700 MHz.  Channel 29 (aka RP21 or something like that) is the repeater channel that automatically transmits on the correct 467.700 MHz frequency.

Try just changing to the repeater channel and setting the repeater input tone there.

Will do, thank you!

[Whiskey363]

I'm a little confused now. As the chart below indicates the GMRS repeater channels, it is the same on the CHIRP software. 

I don't know if I misspoke, but if you have RPT 21 set to an offset of +5 would this not corelate with the below chart of RX 462.7000 and it automatically set the TX to 467.7000? Why would they list it this way if I am supposed to reverse it, being that this is not simplex, but repeater 21?

I want to be clear I'm not arguing and that I am inputting it incorrectly, I'm just trying to understand the way it is written. 

 

GMRS Repeater Channels and Frequencies
Channel	RX Frequency	TX Frequency	Max Power	Bandwidth
RPT15	462.5500	467.5500	50W	25kHz*
RPT16	462.5750	467.5750	50W	25kHz*
RPT17	462.6000	467.6000	50W	25kHz*
RPT18	462.6250	467.6250	50W	25kHz*
RPT19	462.6500	467.6500	50W	25kHz*
RPT20	462.6750	467.6750	50W	25kHz*
PRT21	462.7000	467.7000	50W	25kHz*
RPT22	462.7250	467.7250	50W	25kHz*

*Note: 20kHz Authorized Bandwidth.

[Whiskey363]

For instance, this is how it is listed in CHIRP:

 

29         462.7000           RPT-21             +      5.0000

[WRYZ926]

@Whiskey363 you are correct in that the offset should be right if using a repeater channel, RPT21 in your case. Make sure that you have your TX tone set to match the repeater. 

And yes a 50 watt radio is more than enough to reach a repeater that close with a clear line of sight. While M&P Ultraflex 7 is good coax, it is not the best for UHF/GMRS frequencies. It will have a higher loss than LMR400 cox. But you can make up some of the loss with your 6 dBd antenna. You should not have any issues getting into the repeater even with the higher loss coax at 14 miles.

[SteveShannon]

10 minutes ago, Whiskey363 said:

For instance, this is how it is listed in CHIRP:

 

29         462.7000           RPT-21             +      5.0000

Yes, that is correct.  In your comment you said channel 21.  Channel 21 isn’t the same as RPT-21.  They both receive on the same frequency but RPT-21 transmits with the needed offset. That’s what I (poorly) tried to explain when I said the following:

Quote

So channel 21 is a simplex channel that transmits on 462.700 MHz.  Channel 29 (aka RP21 or something like that) is the repeater channel that automatically transmits on the correct 467.700 MHz frequency.

 

[Whiskey363]

15 minutes ago, WRYZ926 said:

It will have a higher loss than LMR400 cox. But you can make up some of the loss with your 6 dBd antenna. You should not have any issues getting into the repeater even with the higher loss coax at 14 miles.

Bummer, the guys at BUYTWOWAYRADIOS told me this was the best coax I could buy...

I have a lot to learn!

[Whiskey363]

Headed to an emergency service call so won't respond till tonight, but thank you for all the help.

[WRYZ926]

Just now, Whiskey363 said:

Bummer, the guys at BUYTWOWAYRADIOS told me this was the best coax I could buy...

I have a lot to learn!

They were correct if you are going to use the M&P Ultraflex 7 for the HF bands.

[tcp2525]

1 hour ago, Whiskey363 said:

(They are asking if anyone is waiting to jump in so I'm confident they are not ignoring me.) 

My question is, with 50 watts of transmit power, if I can clearly hear them, should they not be able to receive my transmission?

If I understand this correctly, you are bringing the repeater up, but they can't hear you? If this is correct, you have an audio issue, not RF.

[tcp2525]

8 minutes ago, Whiskey363 said:

Bummer, the guys at BUYTWOWAYRADIOS told me this was the best coax I could buy...

I have a lot to learn!

Never believe anyone that has a vested interest in selling you something without checking from a reputable source first.

[Socalgmrs]

With that coax length and 50w eadio you’re still radiating over 75w.  While not a lot it is more than enough for 14 miles.  While I am in no way a fan of the very expensive kg1000 your setbip is totally fine for what you want to do as long as you have line of sight.   I’d have to agree is your tone set up.  I mean an ht with a decent antenna should be able to make the trip no problem at only 14 miles.  A 20w radio with 50ft of lmr400 and a 9db antenna will radiate around 110watts and that’s enough for over 200miles.  You should be fine. 
 

[Raybestos]

1 hour ago, Whiskey363 said:

Bummer, the guys at BUYTWOWAYRADIOS told me this was the best coax I could buy...

I have a lot to learn!

Yeah!  Unfortunately, if you go 100ft or longer with that stuff, you will lose quite a bit of signal on xmit and receive.  I wish BTWR offered hardline/Heliax assemblies for GMRS, which while expensive, is what you really want when going for longer runs.

One possibility worth mentioning.  I have no experience with your antenna, so I don't know if it is prone to this issue or not.  Some antennas perform differently, from different parts of the antenna on semi-duplex (repeater) modes.  As such, you may be where you can hear the repeater just fine but transmitting on 467 MHz, you may be in a total null to the repeater.  IF this is the case, and I know this will be a PITA, you might want to try moving your antenna left or right, or forward or backward on your chimney.  Just a foot or so change in location can be enough to get you out of that null.  Be careful that in doing that, that you don't unintentionally move the antenna where your receiving the repeater is now in a null.

From personal experience Station Master antennas are terrible about this, both the VHF and UHF versions.  They are excellent for simplex, but can be wonky on semi-duplex.  IF you find out the repeater you are trying to use has a Station Master, this may be your problem.

[Whiskey363]

6 hours ago, tcp2525 said:

If I understand this correctly, you are bringing the repeater up, but they can't hear you? If this is correct, you have an audio issue, not RF.

Correct,

   I can clearly hear a lot people using the repeater. When I try and chime in, no one can hear me, I just get a brief RX signal on my radio. 

[Whiskey363]

20 hours ago, Socalgmrs said:

With that coax length and 50w eadio you’re still radiating over 75w.  While not a lot it is more than enough for 14 miles.  While I am in no way a fan of the very expensive kg1000 your setbip is totally fine for what you want to do as long as you have line of sight. 

I edited my original post as I used the incorrect phrase line of sight as opposed to straight line. I am in rolling hills and tree cover, so I was amazed to clearly hear people on a repeater 14 miles away. Expected 5 miles with my setup so pleasantly surprised. 

[Raybestos]

On 11/27/2024 at 6:39 PM, Whiskey363 said:

Correct,

   I can clearly hear a lot people using the repeater. When I try and chime in, no one can hear me, I just get a brief RX signal on my radio. 

Tcp2525 may be on-target.  Do you have another radio to monitor your own with?  Ideally, a ht with a "reverse" feature, or the means to program 467.700 in as a receive frequency.  If not, then try monitoring your transmit audio (voice) on a simplex channel and see if it comes through.  It is entirely within  the realm of possibility that for some reason, your transmit audio is weak or non-existent.

[SteveShannon]

2 minutes ago, Raybestos said:

Tcp2525 may be on-target.  Do you have another radio to monitor your own with?  Ideally, a ht with a "reverse" feature, or the means to program 467.700 in as a receive frequency.  If not, then try monitoring your transmit audio (voice) on a simplex channel and see if it comes through.  It is entirely within  the realm of possibility that for some reason, your transmit audio is weak or non-existent.

We had two instances of this. In one instance the microphone jack had failed such that the PTT worked but the audio line was broken. We knew who it was because of his Roger beep. I soldered his mic jack and his UV5R was back in business. 
In the second instance a guy actually had his microphone hole plugged with some food. 

[Raybestos]

Good catches, Steve!  Without a specimen in front of me at the moment, I don't know if the KG1000G has an audio adjustment on its menu or not.  Possibilities are numerous, including those you have found and fixed.

[Whiskey363]

6 hours ago, Raybestos said:

Tcp2525 may be on-target.  Do you have another radio to monitor your own with?  Ideally, a ht with a "reverse" feature, or the means to program 467.700 in as a receive frequency.  If not, then try monitoring your transmit audio (voice) on a simplex channel and see if it comes through.  It is entirely within  the realm of possibility that for some reason, your transmit audio is weak or non-existent.

I didn't mention this in the original post but I can communicate with my family who are on 935's 5 miles away on channel 17, so I don't believe it's an audio mike issue.

From what I can gather while reading, it appears to be fairly common to be able to receive farther out than you can transmit, particularly when in terrain like I am with trees, elevation, and buildings in the line of sight. 
 

I'm fairly disappointed they steered my towards the coax they did knowing I was going to be running UHF. I imagine I have a lot of loss with 75 feet. Spent a lot of money on it as well, so I don't want to just swap it out. 

[Raybestos]

Well, it looks as though you eliminated that problem as a possibility.  Good job! 

The Messi & Paolini (I call it Nancy Pelosi) cable, if I read their chart right, has a loss of 3.6 db at 400 MHz.  Obviously, it will be a bit higher at 462 MHz so you are probably right at or knocking on the door of 3 db loss, xmit AND receive.  That means if your radio is putting out 50W at the radio, your antenna is getting 25W.  If you can hear the repeater well, it should be able to hear you.

I hear and see so many places promoting LMR400, the Nancy Pelosi, and the like for UHF, even though it is lossy at UHF.  Still, it is better than RG-8.  A 50ft run will probably be okay.  To be honest, at 3db loss, if you hear it you should be able to hit it, which brings us back to my theory that you may be in a good spot to hear it on 462, but an absolute null at 467.  I know it is probably the last thing you want to do, but I would go on the roof and move the antenna a foot or so sideways and or forward and backward.  To prevent additional such trips, have your wife or other trusted person in your radio room, ready to try and key up the repeater at your direction.  If possible, back away from the antenna when they do so to minimize body capacitance and other possible weirdness which might change once you are back on the ground.

This brings another thought.  Can you hit the repeater with the 935G from inside your home or outside?  If so, it is very likely a null you are dealing with.

 

 

https://messi.it/en/comparison-chart--attenuationpower-ratio.htm