rickswa Posted December 2, 2009 Share Posted December 2, 2009 Hello,I've been using the test antenna that came with my EDM transmitter, but the range is really quite limited since it's in my basement. When my house was built, they put an FM antenna in the attic (the kind that looks like a x-mas tree laying on it's side). I have a RG6 cable from there to my basement and can hook this to my EDM to get more range. My only concern is that I am wondering if it is possible to damage the transmitter by using this antenna. I don't know what the brand or specs are of it but I don't want to hook it up if it's going to burn the transmitter out. Anybody able to help me with this? Thank you! Link to comment Share on other sites More sharing options...
Darryl Lambert Posted December 2, 2009 Share Posted December 2, 2009 The standard rooftop antenna is called a Yagi after the Japanese engineer who invented it in the 1920s.A Yagi is a directional antenna. It must be aimed at the transmission tower. Does it look like this?These are mainly used for receiving.I have a FM transmitter ( not EDM ) and the only thing they warn you about it is powering the unit with NO antenna. I think as long as you have an antenna hooked up it should be o.k. But I'm not that familiar with the EDM unit. In my opinion this is a poor choice because it was designed to receive and it is directional. You will get better performance in an antenna that you can tune to your broadcast frequency Link to comment Share on other sites More sharing options...
iresq Posted December 2, 2009 Share Posted December 2, 2009 You won't hurt your transmitter but...EDM is designed to use 50 ohm cable (RG8 or RG58). The combination of RG6 and your FM receiving antenna might not produce acceptable results. If not you could buy or build a ground plane or dipole antenna for your attic. Either option will give you great results and are inexpensive.Did you try turning the power switch?A great discussion on DIY antenna's can be found Here Link to comment Share on other sites More sharing options...
rickswa Posted December 2, 2009 Author Share Posted December 2, 2009 thanks for the replies. That's exactly what my antenna looks like (minus the UHF components). I turned on the transmitter and it actually has plenty of range and great quality for what I need right now. As long as you think that it wont damage the transmitter, I am happy with this setup using the RG6 (70ohm) cable and that receiving antenna. thanks again for the replies. The range is not "miles" but it really is adequate now for what I need compared with using the test antenna. Link to comment Share on other sites More sharing options...
rickswa Posted December 2, 2009 Author Share Posted December 2, 2009 just wanted to give an update. I also emailed EDM and they said that 75ohm cable is fine, but just to make sure the antenna is 75 Ohm and Not 300. Looking at the antenna, I think there is a 75-300 Ohm adapter on it. On one end it has the male f connector that connects to the cable. On the other end, it has two short leads that have terminals which screw onto the antenna. If I use this and it is a 300 Ohm antenna, even with the adapter, will this harm the transmitter? I'm probably just going to build the antenna you sent me the link to or even use rabbit ears like the later post says, but even the rabbit ears are listed at 300 Ohms. So, I'm just confused if a 300 Ohm antenna with a 300-75 adapter on it will damage the transmitter with a designed output of 50 Ohm Link to comment Share on other sites More sharing options...
iresq Posted December 3, 2009 Share Posted December 3, 2009 Your fine. The diy dipole uses the 300 to 75 adapter.As stated earlier, the biggest issues with transmission is not having enough (or any) antenna. Having too much (antenna or resistance) provides transmission distance/quality issues. Link to comment Share on other sites More sharing options...
Jerry Budelman Posted December 3, 2009 Share Posted December 3, 2009 Chiming in here if I may....The little box that converts from 50 ohms to 300 is called a balun (BALanced to UNbalanced). These should work fine if they are designed for frequencies as low as the FM broadcast band. In the days of "traditional" TV broadcasts, channel 2 was as low as 50-60MHz, so it should not be an issue. These little units are designed for very low power however, so your transmitter should not put out much more than 25 milliwatts.Transmitters in general do not like to be connected to any antenna that is not fairly close to to their "desired" impedance, most often 50 or 75 Ohms. There is no such thing as "Too much" or "Too little" antenna; only impedence counts as far as the transmitter's happiness is concerned. Having said that, if the output power of your transmitter is very small (e.g. 25 milliwatts), it probably won't be hurt by an antenna that is not of the "correct" impedance. If your power is much more than that, a) you're probably not legal and you will have to pay much closer attention to your antenna correctness and any balun that is connected.If you really want to know if the antenna is loading the tranmitter properly, you will need some instruments that you might borrow from a Radio Amateur (HAM operator). If you know one, check with him/her.I use a RAMSEY stereo FM transmitter (built from a kit), and it doesn't much care about the antenna or even if it's connected (no signal of course). The same outfit offers a kit for a reasonable dipole antenna. It's enclosed in PVC pipe and is weatherproof etc. I've used it for several years.Hope this helps.Jerry Budelman (WA1BNC) Link to comment Share on other sites More sharing options...
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