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HiLast night when I installed a new tuner, I was listening a jazz station that
doesn't have a strong signal.I was working on the back of the stereo system and I lost the station when I moved the
RG6 coax behind the tuner. If moved again the wire and the station cames in again. I
looked at the connexions and found that every contact was correct.Every time a station has a weak signal, it seems to do the same thing. It doesn't do that with strong signals.
The RG6 goes from the tuner 75 ohm inputs to a Yagi antenna in the roof. The lenght of the cable is about 40 feet. It is connected with a 75 ohm to 300 ohms transformer near the antenna.
Coax wire shouldn't work as an antenna right ?
I know that RG6 coax isn't the same quality as RG59 Can it be the problem ?
Will I have a stronger signal If i use RG59 instead of the RG6 ?
Thanks a lot
Marc Legare
Follow Ups:
I was bedeviled by something like this for years, then I solved it for my system at least.Started with 50' of regular coax from an attic mounted TV antenna through a 300-75 Ohm balun and down through a coax amp. Similar intermittent reception symptoms to yours whenever I approached the cable or whenever it was moved even slighty. In fact, it kept cropping up intermittently without any action on my part; I started to suspect that the cat was moving the cable.
Played with the connections at all points except the attic. No change that lasted. Played with cable placement all over the place, but still same problem kept coming back.
Swapped out the captive PC on the coax amp for a shielded DIY PC and got an improvement, but still had that intermittent problem you describe.
Taking out the coax amp or swapping it for other models (up and down in terms of amplification) only impacted the reception overall, but not the intermittent symptom you describe.
Started swapping out every piece of RG58(?) coax for RG6 quad shield and got much reception improvement, but still had the damned intermittent symptom you describe. Was making me really nuts.
On a last ditch effort after reading about antennas a lot, I detached the coax from the attic antenna run, shortened it to 25', and tied it into an ordinary Radio Shack FM specific Yagi outside the house. Did up a minor inductor tweak and a couple of current balun tweaks per Brian Beezley's site. Tested it out at 6' and 1.5' off the ground (it still sits on chairs in latter position) and was amazed at the result!
Floored is more like it. For the first time I had consistently high grade FM reception on all available channels, strong and weak, in stereo that rivals some CDs. No kidding! Really great.
But the best part was that I have never since gotten one single incident of that transient loss of signal you describe so well that I thought was linked to the cabling somehow. Nada.
So do yourself a favor and check out what kind of antenna or antenna comnections you're using (if you have an FM specific antenna) first. Then move down the chain and see what happens. If my experience is anything typical, I learned the old lesson that the antenna determines everything FIRST.... YMMV
.
Check out Brian Beezley's whole website here, BTW.Now he lists it under the manufacturer, Antennacraft, but he gives the RS part # as 15-2163. Some Shacks may still have them; mine did.
If you want to try this, at RS it's only $24! So run, don't walk. You can always give it back for a refund if unsatisfied. But I was very very satisfied...
bartc:The RS WebSite only pulls up a installation manual. However, the Antennacraft FM-6 (along with the 4-element Winegard PR-6000) is available from the Site below.
The Radio-Locator link that Beezley provides is a gem. There I learned that a bunch of my stations are coming off Mt Diablo. KCSM has a 10W (!!) translator there, KFOG-3 is a 165W booster.
Thanks for the p/n.
Here's the right URL>
Yes, Beezley's site is a real gem all the way around. Lots to find from there as well. Can't remember where I found it, but one guy took off from there and did some really neat directional stuff with added elements in other configs and did well with it on reception (website below).Where are you? East Bay?
I get my stuff on the Peninsula from antenna in Marin, SF and over here on this side, close to KCSM (my favorite of all). That RS works fine in Foster City in the flats.
It was just over the summer that I was able to call up the part number on RS site and find where they had them stashed. Maybe they really have discontinued it altogether. Looks as though the alternate you found has a great price too.
KCSM is giving a run for the money - and is actually leading - my other alternate jazz reference; 50kW KXJZ out of Sac. KCSM is a superb FM station.Along with the baluns and coax chokes, did you do the 1 microhenry inductor across the antenna connection?
I did 2 current baluns (really easy) and also the inductor.At first I just bought an inductor, but was advised to make the simple air core inductor Beezley suggests out of bare wire. Bought the wire at OSH and while in the store simply wrapped it around a 1" pipe to get the exact shape and dimensions. Then hammered out the bent ends to get a mock spade for connecting at the terminals. Also really easy.
I did the extra director tweak as well. Easy enough to extend the spine with a length of PVC pipe. Bought some 3/8" aluminum tubing stock in plumbing section of OSH (comes as spiral, so you need to straighten it out slowly) and attached that at the desired length. Works great!
This whole deal is a no-brainer, but do use good RG6 quad shield and a decent RS gold balun ($6).
Had I the room and patience, I would have also done the 2 antenna thing he suggests, but I simply didn't need it.
59 is smaller gauge than 6; so stick with the 6. The shield of the coax is also acting as part of the antenna system.I can change FM reception by moving around the room or going into an adjacent room. Like cats and women, you'll go nuts trying to figure out the best solution for all the stations you want to hear. FM reception will also vary by time of day and external weather conditions.
therefore you will get a little (antenna) gain by having it between the tuner and antenna. This is especially true if the length happens to be a multiple of the wavelength of the station you are trying to recieve. This affect is most often known to and exploited by hardcore DX'ers.Since you are essentially moving a piece of the antenna, ie reorienting it in the EM fields that is the station you are recieving by moving the coax, it doesn't suprise me that you would hear differences in reception especially on weak stations.
Re coax as antenna, take a look at Brian Beezley's FM page, you can make a coiled portion of the coax act as a current balun, to limit RF pickup by the shield. Might help. Probably a good idea to keep the line as short and direct as possible, and nail it to walls, etc. so it doesn't move around. It does have inductance and that well change with loops, etc., in it.
Dale
It could also be a break in the cable. RF can jump small breaks because the ends couple capacitively. It could be that when you bend it just wrong you decrease the capacitive coupling and hence the signal strength. RG-6 is certainly beefy stuff; your problem should not be attenuation (in a good cable). So my guess is that you have a defective cable.The only way I can figure to test it is to remove the cable, test for continuity and shorts. It might be that when you jiggle it just right, you get a continuity failure. In the same position, you should get some kind of capacitive reading through the cable. If you do, that would confirm the problem. If that's the case, you're out a cable. Good luck!
it only happens on weeak stations and not strong stations. A cable break would affect both weak and strong stations equally badly, ie they would both disapear during the broken wire conditions. Also the broken wire pieces are not going to have enough capacitance between them to pass enough signal to drive the recieve, no matter how strong the station.
The coax needs to be clear of all metal for 6-12" around it. Metal objects close to it may affect the impedance, and cause more mismatch.I'd also check the cable shield to F connector resistance. This is a common area for corrosion and problems on old cable, especially homebuilt cables. I've had good luck with the twist on gold F connectors from Radio shack, but you must get preceisely the correct one. Forget about crimp connectors unless you have the expensive crimping tool. The cheap crimp tool just creates problems down the road.
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