Can someone please explain what the difference is between the 300ohm and 75ohm antennas? And what one is better? I’m lost as a goose in a snow storm...
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300ohm Or 75ohm antenna?
- Thread starter jobrewer1983
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The 300 ohm flat lead will have less loss per foot, the 75 ohm coax will be effected less by interference.
Basically your antenna will be one or the other output and then the receiver also should match. The cable used should be the one with the least amount of adapters needed.
A 75 ohm antenna then cable to a 75 ohm input. Best
A 75 ohm to 300 cable will need a adapter if going to a 300 ohm input on receiver.
Basically your antenna will be one or the other output and then the receiver also should match. The cable used should be the one with the least amount of adapters needed.
A 75 ohm antenna then cable to a 75 ohm input. Best
A 75 ohm to 300 cable will need a adapter if going to a 300 ohm input on receiver.
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My tuner has both 300 and 75ohm. I have the adapter. Just hooked up a cheap rabbit ear antenna and it seems to be doing a good job.
Using the 75ohm and it’s working well!
HTHMAN
Super Member
It is not the antenna that is either 75 or 300 ohm, but the lead. A 300 ohm antenna either uses a 300 ohm lead to the receiver or connects to a balun that converts it to 75 ohms so you can use co-ax. Then at the receiver you can either use another balun to reverse back to 300 ohms or a direct 75 ohm connection if your receiver has it. if you have a 75 ohm antenna, it has a balun already built in.
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Ac
Many Yagi’s use a simple dipole as the driver element and 75ohm cable matches it.
There are other things to consider, but this is the basic gist of it.
Actually it is the antenna that dictates which feedline to use. A simple 1/2 wave dipole has an input impedance around 70ohms. This would match the 75ohm feedline well. However, a folded dipole, which is the type that most ribbon antennas are that were supplied with receivers, have an input impedance 4 times that of a basic dipole. 300ohm twin lead matches that well.
Many Yagi’s use a simple dipole as the driver element and 75ohm cable matches it.
There are other things to consider, but this is the basic gist of it.
tngeorge
New Member
Hey all, I am relatively new here, and would like anyone’s opinion.
I have a Pioneer sx3900.
My favorite local station has 2 towers, one 20 miles south, at 600watts (from their website, I think that has to be a typo?). The other tower is about 30 miles northeast, 50kwatts. I am trying to get a clear signal from the 50k tower, but it seems to be alluding me. Their website says the power level at my home is around 50-70dbu. I have no idea what all that means. Terrain is pretty flat.
Now my situation:
The 3900 has a max of 5 bars for tuning. Best I can get from the 50k tower is 2 bars on a clear day.
I have a dipole antenna, directly connected to the 300ohm input. The antenna sits just above the 3900 on the first floor. One leg points north-south, the other east west.....that’s the best reception I can get.
i tried connecting coax to the 75ohm input (screw on, no female connector).
The other end of the coax I connected via a splitter to my hdtv antenna (roof mount). Reception was worse.
I’ve tried moving the dipole upstairs, no improvement.
So right now I have both connected, and nothing more than 2 bars on the indicator.
Am I banging my head against the wall trying to get better reception?
Other ideas?
thanks.
I have a Pioneer sx3900.
My favorite local station has 2 towers, one 20 miles south, at 600watts (from their website, I think that has to be a typo?). The other tower is about 30 miles northeast, 50kwatts. I am trying to get a clear signal from the 50k tower, but it seems to be alluding me. Their website says the power level at my home is around 50-70dbu. I have no idea what all that means. Terrain is pretty flat.
Now my situation:
The 3900 has a max of 5 bars for tuning. Best I can get from the 50k tower is 2 bars on a clear day.
I have a dipole antenna, directly connected to the 300ohm input. The antenna sits just above the 3900 on the first floor. One leg points north-south, the other east west.....that’s the best reception I can get.
i tried connecting coax to the 75ohm input (screw on, no female connector).
The other end of the coax I connected via a splitter to my hdtv antenna (roof mount). Reception was worse.
I’ve tried moving the dipole upstairs, no improvement.
So right now I have both connected, and nothing more than 2 bars on the indicator.
Am I banging my head against the wall trying to get better reception?
Other ideas?
thanks.
HTHMAN
Super Member
To get better reception, you can try several things. Bigger antenna, directional antenna, signal booster, raise antenna height, outside antenna etc. FM is pretty much line of sight. Trees, buildings, hills etc in your way? If you are hooking the 300 ohm dipole to a 75 ohm cable, you must use a balun.
the skipper
Professional Curmudgeon
you're gonna need more antenna and as high up as possible. those dipoles are fine for very local reception but that's about it.
an omnidirectional antenna on the roof like this will help.
https://www.amazon.com/Winegard-HD-...fix=omnidirectional+fm+antenna,aps,204&sr=1-4
an omnidirectional antenna on the roof like this will help.
https://www.amazon.com/Winegard-HD-...fix=omnidirectional+fm+antenna,aps,204&sr=1-4
Height is king for reception. Almost any antenna outside will be better. You can try setting the dipole vertically like a sideways “T” this will make the pattern more omnidirectional, but if you can get even a basic dipole like this outside, it should make a world of difference. FM is line of sight so the signal will not curve over the horizon. The height of both transmitters will affect the range more than the power. To reach out 30 miles, the transmitter antenna needs to be about 500 feet tall with no obstructions like mountains or large hills that can shade your location.
To avoid that loss, wherever possible I strip the coax to separate the outer braided shield (ground) wire from the center solid one, then connect them to the appropriate binding posts or terminal screws on the back of the tuner or receiver. A couple of my units don’t have the F-connector for 75-ohm anyway, but do have strain relief for coax cable.
Prior to widespread use of the infamous f-connector, this was the norm. A crappy way to "terminate" coax to the back panel. It took almost nothing to bugger up such a lame method of connection, as it was about impossible to physically secure the feedline to the rcvr/tuner. It took nothing to yank such an arrangement loose from the micro-clamp supposedly securing the cable to bulkhead. A couple of fahnstock clips wouldve been better. Easier to reconnect if pulled loose.
The thing is, most gear with just the screws or spring terminals were intended for 300 ohm connections, as in flat 300 ohm twin lead. This was the predominant setup way back when. If this is what one has, it's SOP to use a balun between tuner & feedline if one insists on using coax.. But-if there's an f connector, or even the ill-conceived PAL connector, just direct-connect, as those so-equipped items are set up for 75 ohm input impedance. Fwiw, some f-connector push-on couplers can be crammed onto a PAL fitting. That being the case, if it fits, do it!.
