Repeater TX question

[RichM]

New Technician here. I have an outdoor VHF antenna with good coax on a 25’ mast. The 2 repeaters I would like to use are received with a full signal. However I cannot get voice into them on TX, just an occasional squelch tail or kerchunk. There is a fairly large hill between my QTH and the repeaters. I know my radio programming is good because I hiked to the top of said hill and was able to get in both repeaters no problem using a rubber ducky antenna. I’m using an 8w HT for both the hiking experiment and connected to my outdoor antenna. There are 2 other repeaters opposite of the hill that I can get into with full signal from my QTH so it is definitely not the radio or antenna set up.

It seems obvious to me that topography is the problem. My question is would using more wattage allow me to over come this issue? My instinct says no but the fact that I hear them with full signal and can occasionally get a squelch beep makes me wonder if it might work. I am considering trying a mobile as my base station but wonder how much extra power would help (if at all)? There are lots of inexpensive 25w mobiles available that would provide triple the power I am using now. For twice the price there are some 65w mobiles available as well. If the extra power would help then I assume more would be better?

I am hesitant to throw money at this just to get the same result. A taller antenna is not an option either. I suppose if the mobile didn’t work I could use it in the car but then I would be stuck with the power supply. What do you think?

 

[ladn]

Congratulations RichM!

Let's start with the obvious:

• Your radio seems to be properly programmed since, when you change location, you can access the repeaters.

Now, the less obvious. You mention an "outdoor VHF antenna with good coax". Are we talking a Larsen commercial grade VHF base antenna with 3-6dB gain fed with 1/2" hardline and Type N connectors, or are we talking a Bingfu mobile antenna with no ground plane fed with Chinesum® RG-8 type cable from Amazon? Have you looked at the SWR and loss of your cable and antenna? And what's the claimed gain on your antenna?

You also mention an "8w HT". What brand and have you tested it to see if it really is putting out 8w?

Based on the information you provided, my suspicion is that your problem may be a combination of location/topography and less than optimal equipment choices, resulting in a loss of transmitter efficiency and power. The repeaters you can hit have a more direct signal path, so your reduced transmitter performance is stiff sufficient to connect.

Kindly provide additional details on your equipment so that a better evaluation can be made.

 

[RichM]

I’m using RG8 coax with PL259 connections. The antenna is a Radio Shack 20-179 VHF scanner antenna mounted on top of a flag pole. While it is not specifically designed for transmitting there are many online reports of using it for 2 meter TX pushing up to 200w through it. I don’t have test equipment to determine antenna gain or radio output. I was relying on reports of full quieting and loud and clear on the other 2 repeaters. Radio is a cheap Baofeng UV5R8w so the wattage claim I’m sure Is dubious at best. My Rube Goldberg approach to this is to see if this is even possible at my QTH before investing in better equipment. Thanks for your help.

 

[prcguy]

I’m using RG8 coax with PL259 connections. The antenna is a Radio Shack 20-179 VHF scanner antenna mounted on top of a flag pole. While it is not specifically designed for transmitting there are many online reports of using it for 2 meter TX pushing up to 200w through it. I don’t have test equipment to determine antenna gain or radio output. I was relying on reports of full quieting and loud and clear on the other 2 repeaters. It’s a cheap Baofeng UV5R so the wattage claim I’m sure Is dubious at best. My Rube Goldberg approach to this is to see is this is even possible at my QTH before investing in better equipment. Thanks for your help.

That antenna is not tuned very well in the 2m ham band, its centered more around 155MHz. A better antenna would go a long way towards making it into the repeaters. Also consider most repeaters run 50w or more output and you are running about 5w, so the path is not reciprocal. You can hear the repeaters but your sending them less than 10% of what they are sending you.

 

[RichM]

Thanks for the reply. I believe you may be right about the antenna, it was already up so I thought I would try it. The good reports I got on the other 2 repeaters made me think it may be working well enough.

I understand the repeaters are using more power than my HT which is why I asked about using more wattage on my end. Thanks for the help.

 

[nd5y]

Try moving the antenna vertically or horizontally a couple feet and see how much difference it makes.

 

[RichM]

Try moving the antenna vertically or horizontally a couple feet and see how much difference it makes.

It is mounted on top of a flag pole so not really possible. The reception with this install has been superb for everything analog in the many years I have been using it.

 

[ladn]

I’m using RG8 coax with PL259 connections. The antenna is a Radio Shack 20-179 VHF scanner antenna mounted on top of a flag pole.

Thanks for the update. Is your RG8 coax also Radio Shack brand? And does your antenna have a ground plane/counterpoise

 

[RichM]

I honestly don’t remember where I purchased the coax, it is around 3/8” thick and not very flexible. As I already mentioned the antenna in question is an RS 20-176 scanner antenna not designed for transmitting but used for TX in the 2 meter band by others with good results. The reports I got of full quieting and loud and clear made me think it seems to be working well enough on the 2 LOS repeaters.

 

[RichM]

Update: a local Elmer who is familiar with the topography in question said “You can shoot as many watts as you want into that hill side, it won’t matter as the repeaters are all line of sight.”

I think I will cut my losses and just be content with what I have. I‘m really more interested in emergency communication rather than rag chewing anyway and I am hitting the 2 local repeaters just fine. If I really want to participate in the nets on the other repeaters I can use EchoLink which to me seems like cheating but it does open up the whole world of repeaters to me with zero monetary investment.

Thanks for everyone’s help, 73’s.

 

[alcahuete]

Update: a local Elmer who is familiar with the topography in question said “You can shoot as many watts as you want into that hill side, it won’t matter as the repeaters are all line of sight.”

I think I will cut my losses and just be content with what I have. I‘m really more interested in emergency communication rather than rag chewing anyway and I am hitting the 2 local repeaters just fine. If I really want to participate in the nets on the other repeaters I can use EchoLink which to me seems like cheating but it does open up the whole world of repeaters to me with zero monetary investment.

Thanks for everyone’s help, 73’s.

With all due respect to your local elmer, line of sight works both ways. Ask your elmer to explain (okay...don't actually do it, I'm being an a$$) how line of sight is working just fine from the repeater to you, but not from you to the repeater. Makes absolutely no sense.

Yes, line of sight, generally speaking, is how VHF/UHF works, but if you're receiving the repeaters full quieting, something else is at play. My opinion, it's either the antenna, your power output, or both. While that antenna might work for transmitting, so will a coat hanger and paper clip. But those aren't necessarily the best antennas for the job. As well, a good 50w mobile radio will allow you to do things you can never do with 5w from a handheld.

 

[nd5y]

Yes, line of sight, generally speaking, is how VHF/UHF works, but if you're receiving the repeaters full quieting, something else is at play. My opinion, it's either the antenna, your power output, or both.

Don't forget the repeater. Not all of them built and operated properly by technically competent people. Some of them are just $hitboxes that can't receive.

 

[Grounded]

It seems obvious to me that topography is the problem

No, sir, it is not a topology problem but rather an amateur radio problem. Nearly all amateur radio repeaters are crocodile sites: all mouth and no ears. Not many amateur radio repeaters are BALANCED to serve either portables or mobiles. Amateurs crank out as much power as possible without considering a balanced system. I bet many of you never heard of it.

A balanced system means the repeater's effective radiated power (ERP) equals the portables or mobiles it serves. For example, your typical mobile radio transmitter power is roughly 40 watts with a 3 dB gain antenna; the ERP equals roughly 80 watts ERP. That tells the RF train driver (enjunere) that the repeater antenna ERP shall be 80 watts. When designed correctly, if you can hear the repeater, the repeater can hear you equally well. Same if you want to balance for portables, you limit the repeater ERP to 5 to 10 watts.

Amateurs do not do that; they go for maximum smoke at the repeater site. No thought is given to balancing the system. For example, a 250-watt transmitter with a 10 dB gain antenna can get an ERP of 2500 watts, trying to talk to units with 5 to 100-watt ERP. The result is a crocodile site, all mouth, and no ears.

 

[alcahuete]

No, sir, it is not a topology problem but rather an amateur radio problem. Nearly all amateur radio repeaters are crocodile sites: all mouth and no ears. Not many amateur radio repeaters are BALANCED to serve either portables or mobiles. Amateurs crank out as much power as possible without considering a balanced system. I bet many of you never heard of it.

A balanced system means the repeater's effective radiated power (ERP) equals the portables or mobiles it serves. For example, your typical mobile radio transmitter power is roughly 40 watts with a 3 dB gain antenna; the ERP equals roughly 80 watts ERP. That tells the RF train driver (enjunere) that the repeater antenna ERP shall be 80 watts. When designed correctly, if you can hear the repeater, the repeater can hear you equally well. Same if you want to balance for portables, you limit the repeater ERP to 5 to 10 watts.

Amateurs do not do that; they go for maximum smoke at the repeater site. No thought is given to balancing the system. For example, a 250-watt transmitter with a 10 dB gain antenna can get an ERP of 2500 watts, trying to talk to units with 5 to 100-watt ERP. The result is a crocodile site, all mouth, and no ears.

You're overlooking the gain on the receive side.

That's great advice for a commercial repeater or public safety repeater, where you want to make sure the handhelds can get in, but TBH, I don't cater to the lowest common denominator (someone inside a car or house with a $18 Baofeng) when it comes to amateur radio repeaters. I strive for maximum coverage using real radios.

Why would you ever limit your coverage to say 10 miles so your Baofeng user can get in, when you can go out to 50 miles for those running nice mobile setups?

 

[buddrousa]

Was called to a site complaint was 100 watt Mobiles had a little noise on them 100 miles away.
Site
Tower 400 foot
Feedline 1 5/8 Hardline
Antenna 2 Co Phased DB224's 1 up 1 Down
Repeater VHF 150's
Power 350 Watts out of the Duplexers
I left told them I wanted no part of my name on this

 

[prcguy]

Was called to a site complaint was 100 watt Mobiles had a little noise on them 100 miles away.
Site
Tower 400 foot
Feedline 1 5/8 Hardline
Antenna 2 Co Phased DB224's 1 up 1 Down
Repeater VHF 150's
Power 350 Watts out of the Duplexers
I left told them I wanted no part of my name on this

That sounds like a very nice entry level system.

 

[K9KLC]

I’m using RG8 coax with PL259 connections. The antenna is a Radio Shack 20-179 VHF scanner antenna mounted on top of a flag pole. While it is not specifically designed for transmitting there are many online reports of using it for 2 meter TX pushing up to 200w through it. I don’t have test equipment to determine antenna gain or radio output. I was relying on reports of full quieting and loud and clear on the other 2 repeaters. Radio is a cheap Baofeng UV5R8w so the wattage claim I’m sure Is dubious at best. My Rube Goldberg approach to this is to see if this is even possible at my QTH before investing in better equipment. Thanks for your help.

Invest in better equipment and you won't need to ask if it's possible any more. I'll be direct. Get a proper base set up. A base radio (usually a mobile on a power supply) proper coax and an actual external base antenna. Then you will understand.

 

[K9KLC]

No, sir, it is not a topology problem but rather an amateur radio problem. Nearly all amateur radio repeaters are crocodile sites: all mouth and no ears. Not many amateur radio repeaters are BALANCED to serve either portables or mobiles. Amateurs crank out as much power as possible without considering a balanced system. I bet many of you never heard of it.

A balanced system means the repeater's effective radiated power (ERP) equals the portables or mobiles it serves. For example, your typical mobile radio transmitter power is roughly 40 watts with a 3 dB gain antenna; the ERP equals roughly 80 watts ERP. That tells the RF train driver (enjunere) that the repeater antenna ERP shall be 80 watts. When designed correctly, if you can hear the repeater, the repeater can hear you equally well. Same if you want to balance for portables, you limit the repeater ERP to 5 to 10 watts.

Amateurs do not do that; they go for maximum smoke at the repeater site. No thought is given to balancing the system. For example, a 250-watt transmitter with a 10 dB gain antenna can get an ERP of 2500 watts, trying to talk to units with 5 to 100-watt ERP. The result is a crocodile site, all mouth, and no ears.

I can assure you not all amateur repeater owners or clubs do this. And yes by his own experimentation and testing he was able to help narrow down the problem. If you can't hit a repeater at the bottom of the hill on some HT but at the top you can ok an HT with a rubber duck if say it's working ok. The OO actually solved his own situation. Now he just needs to make the next steps to finish it.

 

[AK9R]

Perhaps commenters should focus on addressing the OP's question.

Oh, wait, the OP announced almost a month ago that he had an answer for his problem that he accepted and that he was moving on.