I am in the process of setting up a station right now. I am kinda up in the air on what antenna to use. I have been a cb operator for 10 years now and run a 3 element horizontal beam about 30ft up. I have been looking at the berkeley dipole setup and it seems to be pretty good. But i was also looking at the comet 5/8 wave antenna and that seems to be another good choice also. My station antenna will be on a mast above my 3 element beam setup say about (40-50ft off the ground) i have for my cb now. I plan on using one of the berkeley kits also.. which one i dont know yet, probbly the 15 watt transmitter seems to be a good start then i can allways add a amp to it. Any other antenna's that i dont know about besides the dipole and that 5/8 wave comet that i could use?
FM antennas are small enough you could chose a colinear (like two or more vertically stacked dipoles) or a J-pole antenna would be my personal choice. But if you found a smoking deal on the others, go for it!
Since you're tower mounted, what you have to mind is line losses. Here's some tips:
- Avoid RG 58 for FM like the plague. - RG8 is OK. - RG6 is OK too *if* first you match the SWR *at* the antenna. Then despite the RG6 being 75 ohms, it will reflect the 50 ohm load fine, since you've tuned out the reactive +j component. - If you use RG8, use "N" connectors. UHF connectors are too lossy at FM. - If you use RG6, use a BNC or "N" connector is cool.
FM antennas are small enough you could chose a colinear (like two or more vertically stacked dipoles) or a J-pole antenna would be my personal choice. But if you found a smoking deal on the others, go for it!
Since you're tower mounted, what you have to mind is line losses. Here's some tips:
- Avoid RG 58 for FM like the plague. - RG8 is OK. - RG6 is OK too *if* first you match the SWR *at* the antenna. Then despite the RG6 being 75 ohms, it will reflect the 50 ohm load fine, since you've tuned out the reactive +j component. - If you use RG8, use "N" connectors. UHF connectors are too lossy at FM. - If you use RG6, use a BNC or "N" connector is cool.
Peace!
Awsome, i have some extra LMR-400 i might end up using.. would that be over-kill for a small fm station? I could deffently get away with stacking 2 dipoles but if the j-pole is the way to go i might end up with it.. here is a link i found lmk if it seems to be a good buy... 55 shipped and its all copper.
Really, there is no overkill because sure, you're using a fraction of the power the cable is rated for, but it's the low loss you want. If you have for example a 3dB loss in your cable run, you've burned 50% of your transmitter power as heat in your cable!
That LPFM J-Pole at www.jpole-antenna.com/products.php#lpfm looks good. With copper retail prices still skyrocketing despite the comoddity price falling, doubtful you could build one for much cheaper.
awsome man! ya the lmr-400 is crazy, deffently wont be lossing anything with this hardline. Ive been looking at the EDM transmitters and think ill probbly get one of those, then add a berkely amp onto it down the road. I have everything grounded good but how is the copper for lightning? I just dont wana put up a big ol lightning rod, but if the ham guys are using it without a problem then it should be pretty solid.
Copper is just as nasty of a lightning rod as aluminum as a carbon coated string... if it conducts more than the surrounding air, it'll attract it
But, if it's going to be on your tower, that seems like a moot point, since the tower is already there. If it hits the J-pole, it would have hit the tower anyway.
I would go with the EDM transmitter too, over the FRB exciter. Amp wise, you might want to check out the PCS 15 watt amp. The Comet antenna would be a good choice if you have the $$$, otherwise the FM DX tunable GP antenna work good if you don't need the 3db gain and need a compact size. EDM has a 250 milliwatt LCD version do out this month.
K good day all, and thank u for ur help in advance... I ordered a 5 watt FM transmitter hoping to get about 4 or 5 miles in the city. Knowing I was only gonna get a 1/2 to 1 mile. I am in the process of setting up a station as well...and would like to know if is should dump the stuff I purchased or add an FM amp to the transmitter, and get a different antenna. I would like to know what I would need to go 10 to 15 miles in the city.
Here is a link to the transmitter and antenna I have...
I have owned a 5 watt and a 50 watt transmitter from that site. The 5 watt cube just about makes 5 miles. The antenna rusts real bad. The 5 watt and the 50 watt dont have a 15khz filter and cause a shussh sound in the treble . The audio is very sensitive. There is 2 vr adjustments inside the case of the cube, near the mic input. Those can be adjusted for higher audio input. One is left the other is right. Also it performed better with the case open with a fan blowing in. I had to filter the audio input to get rid of an annoying hum. A good low pass filter also. It was harmonics bothering my mixing board. Oh I'm using a ramsey fm 200 antenna . a 175 watt amp , lpf. and a hlly tx 99 now . Sounds like a pro station. It's hard to tell.
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