Anyone Have Their FM02 Mounted in the Same Enclosure as the Helix??

[mikentn]

Evening, all;

Question - have any of you mounted your FM02 (or equivalent) in the same enclosure as your Helix, and if so, did it cause transmission issues for you? I'm fighting a transmission issue at the moment where I'm getting very poor range out of my transmitter. My house is 80 feet from the road, and when driving slowly in front of my house, the signal fades in and out. I've tried both a modified ground plane and dipole antenna, and the situation really hasn't changed.

Any thoughts or ideas will be much appreciated.

Thanks!

Mike

 

[ukewarrior]

Please post more info about how you are cabled and the length of your antenna cables.
Mounting the transmitter with the Helix shouldn't matter. The FM02's radiation is directly out the antenna wire.
Are you using 50 ohm cable? How long of a cable from the FM02 to the antenna?
I get a good 1/4 mile from my FM01. I run about 30 feet of 50 ohm cable to a ground plane antenna.
How is the FM02 connected to the antenna?
Some pictures may help too.

 

[Warlock]

I have mine mounted in the same enclosure with my Helix and no issues at all..Crystal clear,I used the antenna that came with it plus I got one more off ebay...I got my second fm02 off DIY express and I'm using the antenna that came with it...Works great for at least a half mile as I have it high on my balcony...I might suggest moving your antenna around and see if the transmission clears up or if you can try listening to the music via headphones then try plugging your helix into a stereo to see if the output is clean.Then you can also try using a portable radio close to your transmitter and see if the noise is there..It also might be the power supply you are using..My step down has filters so it doesn't interfere with it at all..As Uk suggested you might want to show some pictures so we can see how it is mounted as well as tell us what power supply you are supplying it with...

 

[mikentn]

I'm using a SMA / BNC bulkhead cable from the FM02 to the outside of the enclosure, and then I was initially using about 20 ft of RG58 between the bulkhead to a modified ground plane antenna that Joe Hinkle designed. Today I tried moving the antenna off of the wall to a spot out in the yard, to no avail. The particular RG58 cable I was using was half of a bnc/bnc cable I ordered online from All Electronics; the cable had an aluminum braided shield which I found odd, so today I found some RG59 at HD that had copper braided shield. I changed out the feed cable to 12 ft of RG59 between enclosure and antenna, and it didn't make a difference. I then made a dipole antenna that had approximately 12 ft of RG59 feed cable as well, and while it is somewhat better, I still get fading in front of my house.

I can take some pictures tomorrow.

Thanks for replying!

 

[bcowan]

I have mine mounted in the same enclosure and have no issues. I get about a block of good signal from the little test antenna that came with the unit and two blocks from the dipole antenna I built from the wiki.

 

[mikentn]

I actually copied your layout inside the enclosure. I was wondering if running the coax beside the AC input to the board might cause issues, but apparently it doesn't. Good to know.

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[bcowan]

I ran the AC on the left side of the enclosure and the audio and coax on the right side on the design I posted. My new Helix V3 has a FM02, REN-W, and wall wart tamer all mounted in a CG-2000 enclosure, so everything is much closer together, and it sounds great also. Have you tried a different FM channel?

 

[mikentn]

Here are some pictures of my Helix and the temporary dipole antenna I made last night. The picture of the lid isn't really clear, but in it I have the 12V wall wart, a LM317 voltage regulator, and an on/off switch for the FM02. In the picture showing the antenna, the Helix is in the CG1500 to the left behind the bush. The other CG1500 has a Ren48LSD in it.

The dipole antenna is made of RG59, and I made it using Idunbenhad's instructions (separating the center conductor and shield, and using those as the elements).




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[Warlock]

My set-up has the helix on the back with the transmitter on the top.Power supply is in another enclosure to make sure noise is not an issue...All my lines are separated inside the enclosure ( meaning all top lines are on the top and never see the bottom till the exit)...Maybe noise is entering into the system some place cutting your transmission distance or causing the interference..
Other then that no idea I wish I could help more..

 

[ukewarrior]

Your antenna seems too close to the house. Is there a balun loop at the point of entrance to the dipole?

Do you have a big tree in the line of sight where the fading occurs?
Your setup in the box looks fantastic, I don't think your problem is there.
Can you provide some closeups of you various connections? I think some of your signal is bleeding to ground.
A close up of the bulkhead connection and others may be helpful.

Here are some pictures of my Helix and the temporary dipole antenna I made last night. The picture of the lid isn't really clear, but in it I have the 12V wall wart, a LM317 voltage regulator, and an on/off switch for the FM02. In the picture showing the antenna, the Helix is in the CG1500 to the left behind the bush. The other CG1500 has a Ren48LSD in it.

The dipole antenna is made of RG59, and I made it using Idunbenhad's instructions (separating the center conductor and shield, and using those as the elements).




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[mikentn]

I ran the AC on the left side of the enclosure and the audio and coax on the right side on the design I posted. My new Helix V3 has a FM02, REN-W, and wall wart tamer all mounted in a CG-2000 enclosure, so everything is much closer together, and it sounds great also. Have you tried a different FM channel?

I stand corrected. No, I haven't tried a different FM channel. 90.1 is vacant on the FM band around here. There is a station on 90.3, but I don't hear it bleeding over.

Speaking of sound quality - do you get the white noise with your Sparkfun mp3 player that Greg discussed in a recent post??

 

[mikentn]

Your antenna seems too close to the house. Is there a balun loop at the point of entrance to the dipole?

Do you have a big tree in the line of sight where the fading occurs?
Your setup in the box looks fantastic, I don't think your problem is there.
Can you provide some closeups of you various connections? I think some of your signal is bleeding to ground.
A close up of the bulkhead connection and others may be helpful.

The antenna is mounted on the wall of the house. I don't have a balun on the dipole at all. I started off with a modified ground plane antenna, and it was worse than the dipole.

There is a big tree at the corner of the neighbor's yard that is in the line of sight to the church parking lot across the street, but that's it. All the trees in my front yard are small (5 - 6 years old). My driveway is to the left of the picture of the house, maybe 50 feet away, and I can barely pick up the signal in my driveway.

Today I tried the following:

I moved the dipole antenna and my Helix to the center pole of my megatree in the front yard. The center pole is PVC, approximately 12 feet high. The transmission quality was worse there than it was when mounted to the wall. I also tried the modified ground plane antenna again at the base of my megatree, and it was even worse. I then made another dipole antenna using the RG58 cable I originally started out with, and it was worse than the RG59 dipole, too.

I really don't think it's an issue with the power to the FM02, since what I'm hearing is akin to an AM radio transmission, where some spots the transmission is clear, and then as you move it fuzzes in and out.

I took another picture of my enclosure. I'll post it here in a sec.

 

[mikentn]

Here is the picture I took of my Helix and FM02 this afternoon. I rearranged the wallwart to keep it from hitting the transformer on the board.

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[gmbartlett]

Have you tried connecting an antenna directly to your FM02 and testing the coverage? This will allow you to check for any issues with the cable between the FM02 and the bulkhead connector.

 

[mikentn]

Have you tried connecting an antenna directly to your FM02 and testing the coverage? This will allow you to check for any issues with the cable between the FM02 and the bulkhead connector.

I thought about trying that today, but I can't get the right angle BNC connector with the BNC/sma adapter in there - not enough space. I'm contemplating mounting my spare FM02 in a separate enclosure tomorrow so I can attach the antenna directly to the FM02 and do some tests.

I'm sorely tempted to order a tuneable ground plane antenna and another RG58 cable with factory bnc connectors as well. The RG59 cable I'm using at the moment has a twist-on bnc connector that I had to install. No one around here carries premade RG58 or RG59 cables.

 

[ukewarrior]

After reading this, I'm wondering about your cable. Those twist on connectors are not the best and lots of folks trim away all of the shield instead of folding it back along the outside of the sheath to make a good connection with the connector. I think it would be money well spent to either get a factory cable or invest in crimp connectors. If I recall, radio shack sells a crimp tool for under $10 for BNC connectors. How far is the wall mounted antenna from the house? Given everything you've tried, the cable does seem like a likely suspect.

I thought about trying that today, but I can't get the right angle BNC connector with the BNC/sma adapter in there - not enough space. I'm contemplating mounting my spare FM02 in a separate enclosure tomorrow so I can attach the antenna directly to the FM02 and do some tests.

I'm sorely tempted to order a tuneable ground plane antenna and another RG58 cable with factory bnc connectors as well. The RG59 cable I'm using at the moment has a twist-on bnc connector that I had to install. No one around here carries premade RG58 or RG59 cables.

 

[mikentn]

I'm going to order a tunable ground plane antenna & 20 ft bnc/bnc cable this morning. Should be in the first part of the week. In the meantime I'll run by RS and see what they have, as well as put my spare FM02 in a separate enclosure for testing as well.

The wall the antenna is mounted to is the outside wall of the house.

This does bring up another question though - where exactly does everyone mount their antennas?

Oh, fwiw I was under the impression that RG58 coax was supposed to have a copper braid, which is why I was having doubts about the first cable I bought (RG58/u), since it had a foil shield, along with a minimal aluminum braid; however, when I was surfing around last night for cables I decided to check Monoprice, and all of their RG58 cables are listed as AU with 48% aluminum braided shield. Just FYI for anyone else looking for RG58.


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[ukewarrior]

It's more important that you run a 50 ohm cable than a 75 ohm cable. I doubt the shield material matters.

I'm going to order a tunable ground plane antenna & 20 ft bnc/bnc cable this morning. Should be in the first part of the week. In the meantime I'll run by RS and see what they have, as well as put my spare FM02 in a separate enclosure for testing as well.

The wall the antenna is mounted to is the outside wall of the house.

This does bring up another question though - where exactly does everyone mount their antennas?

Oh, fwiw I was under the impression that RG58 coax was supposed to have a copper braid, which is why I was having doubts about the first cable I bought (RG58/u), since it had a foil shield, along with a minimal aluminum braid; however, when I was surfing around last night for cables I decided to check Monoprice, and all of their RG58 cables are listed as AU with 48% aluminum braided shield. Just FYI for anyone else looking for RG58.


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[mikentn]

It's more important that you run a 50 ohm cable than a 75 ohm cable. I doubt the shield material matters.

True, but the vast majority of antenna threads on the site specifically mention using RG58 or RG59, with one of the reasons being they have a copper braided shield which handles much better for soldering than foil shielding; so I felt it worth mentioning, because it did cause me to question the quality of the RG58 cable that I originally purchased.

 

[bcowan]

I mount my controller and antenna to the center pole of my mega tree.