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Author Topic: A pretty hard setup  (Read 1717 times)
CTHAM
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Posts: 40




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« on: May 01, 2010, 10:31:41 AM »

Because I live at apartment I can't drill on the outside and all that..

Anyways I just got my Diamond MR-77 mag mount antenna.. to mount on my window AC.

Anyways my primary use was for a home APRS station but what I noticed at 40W on my Kenwood TR-7950 i don't get heard at all but a weather station that's about a little under a mile from me.

I tried everything and changing a few settings under the Tinytrak 4 I set the path to WIDE 1-1, WIDE 2-1 and WIDE 2-2 and I still haven't had any luck.

So I took the unit mobile yesterday turned on the smart beacon and out of a 20 mile drive (White Plains, NY to Riverside, CT) I was only heard once.

One issue I think I have is my antenna at home is only mounted about 11FT from ground level (I live on first floor) and I have a 180 degree view of woods.

I don't think I have any hope at all.. Anyone know which ways I can improve?
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WX7G
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« Reply #1 on: May 01, 2010, 12:31:27 PM »

Sounds like the TR-7950 is having a problem and not the antenna.
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CTHAM
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Posts: 40




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« Reply #2 on: May 01, 2010, 01:43:56 PM »

What makes you think that?
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WG8Z
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Posts: 185




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« Reply #3 on: May 01, 2010, 06:12:29 PM »

Too much or too little deviation? Either condition can make your packets difficult to decode even if RF signal strength is good.
Other possible problem is RF getting back into the transmit audio circuit and distorting tones, sometimes impossible to detect but easy to see on a modulation scope... One would be surprised to see the garbage i've seen being "dusted" out there.
I'm running 7950's on several of my digi's and wouldn't even think of putting one on the air without ferrite beads on the interface cables...Thats what my service monitor tells me... Magmount on the AC would only exacerbate this condition...Old Kenwoods are notorius for lack of RF bypassing on the Mic input.
73
Greg
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CTHAM
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Posts: 40




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« Reply #4 on: May 01, 2010, 06:19:03 PM »

Too much or too little deviation? Either condition can make your packets difficult to decode even if RF signal strength is good.
Other possible problem is RF getting back into the transmit audio circuit and distorting tones, sometimes impossible to detect but easy to see on a modulation scope... One would be surprised to see the garbage i've seen being "dusted" out there.
I'm running 7950's on several of my digi's and wouldn't even think of putting one on the air without ferrite beads on the interface cables...Thats what my service monitor tells me... Magmount on the AC would only exacerbate this condition...Old Kenwoods are notorius for lack of RF bypassing on the Mic input.
73
Greg

Here is a video I posted last night

http://www.youtube.com/watch?v=1lPEHH8HiGg

If I wanted to check with my scope I where would I be checking? the output on the radio or the TT4?

73,
KB1QXO

*edit here is another with the scope connected

http://www.youtube.com/watch?v=j7Bx4XFp5l0
« Last Edit: May 01, 2010, 10:58:50 PM by Michael Lewis » Logged
K0BG
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« Reply #5 on: May 02, 2010, 07:24:05 AM »

The method you're using to 'test' the radio won't tell you much. Depending on the design, the PL tone typically can't be seen, or heard, at the speaker output, and neither can distortion. What you need is a communications monitor. As pointed out above, you need to actually 'see' what the radio is outputting, both in deviation, and PL level.

It is not uncommon for FM radios to be maladjusted right out of the box, brand new. Give them a few years, and it's anyone's guess. In fact, I've seen a few where the PL had more deviation than the audio!
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KC8AHN
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Posts: 108




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« Reply #6 on: May 02, 2010, 10:14:42 AM »

That is an older rig. Are you sure you are really putting out 45 watts? My 7850 will hit the local repeater and hear it, but that is about it. The finals are nearly gone on it. So I guess what I am asking is are you sure your rig is working properly? What is your call sign? It would be easy to see if you are showing up on aprs.fi if we had that information. How far are you from a digipeter? I know for me, I have to drive about 5 miles to hit one from my home, and I have a 5/8s wave ground plane on my tower at 30 feet, but then I am only using and HT.
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CTHAM
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Posts: 40




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« Reply #7 on: May 02, 2010, 12:03:54 PM »

The method you're using to 'test' the radio won't tell you much. Depending on the design, the PL tone typically can't be seen, or heard, at the speaker output, and neither can distortion. What you need is a communications monitor. As pointed out above, you need to actually 'see' what the radio is outputting, both in deviation, and PL level.

It is not uncommon for FM radios to be maladjusted right out of the box, brand new. Give them a few years, and it's anyone's guess. In fact, I've seen a few where the PL had more deviation than the audio!

Where do you get PL tones from? And it's possible to hear a PL tone.. you just need the audio amped and cranked.. but that's really extreme... This radio has no tone board so no tones.

And a communications monitor sounds like something that's going to cost $1,000's

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CTHAM
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Posts: 40




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« Reply #8 on: May 02, 2010, 12:05:21 PM »

That is an older rig. Are you sure you are really putting out 45 watts? My 7850 will hit the local repeater and hear it, but that is about it. The finals are nearly gone on it. So I guess what I am asking is are you sure your rig is working properly? What is your call sign? It would be easy to see if you are showing up on aprs.fi if we had that information. How far are you from a digipeter? I know for me, I have to drive about 5 miles to hit one from my home, and I have a 5/8s wave ground plane on my tower at 30 feet, but then I am only using and HT.

My callsign is KB1QXO

I think a digi might be located in Stamford but from my location I would not be able to hit it unless I got on the highway about 3 miles out.
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KC8AHN
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Posts: 108




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« Reply #9 on: May 02, 2010, 06:19:21 PM »

Here is what is on APRS.FI: http://aprs.fi/info/KB1QXO
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CTHAM
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Posts: 40




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« Reply #10 on: May 02, 2010, 06:26:33 PM »

Here is what is on APRS.FI: http://aprs.fi/info/KB1QXO

yeah that's because I used Ui-view and internet APRS server..

I was out and about today KB1QXO-9 and I was heard when mobile.. however for some reason my position was not being tracked with the GPS connected and a solid lock.
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KC8AHN
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Posts: 108




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« Reply #11 on: May 03, 2010, 02:21:12 PM »

Not sure where APRS.FI has it's information if your GPS is not working. It shows you on the CT turnpike, 73mph traveling in the direction of 96degrees and 121ft in elevation.
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CTHAM
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Posts: 40




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« Reply #12 on: May 03, 2010, 05:29:25 PM »

Yeah I saw that.. I think I fixed the issue of that.. because where it shows me out it took me about 8 min to get to that location, I was using really old firmware it seems
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