I have for sale a Ramsey 25A transmitter with dipole antenna with a few feet of coax and the original Ramsey power supply.
I have NOT tested this in any way beyond transmitting in the house and listening to music throughout my house transitted from it. I have NOT tested it for legal output, spectral purity, range or anything else. As you can't get them anymore, and they're kits anyway, I saw no reason to put it through my usual battery of tests.
The faceplate says it's an FM25. The circuit board says it's an FM-25A. It's revision 1.4 whatever that may mean. Transmit audio sounds fine. It has a hole in the top where the original screw mount whip antenna poked through the lid. I do not have this antenna, just the dipole that comes with it -- it's a TV set telescopic dipole.
I really don't know anything about Ramsey transmitters. Just something I picked up along the way a while back thinking I'd test it in the "lab" but then never did. It's just taking up a bit of workbench space.
$50 including priority mail shipping in the USA. Overseas OK too, but you will have to pay shipping.
TIB
What type of connector does the Transmitter and dipole have?
IIRC Ramsey used RCA. My 25B uses RCA.
uses RCA connector for RF out.
Wonder if the dipole can handle 7 Watts? And how big it is. Probably could get a TNC to RCA adapter. On low power 300 mW would cover quite a bit
Just wondering.
The dipole is simply TV rabbit ears. They have a built in cable that terminates in a standard TV cable styhle "F" connector. There is a coupler that adds on a few more feet of cable, which also terminates in a type "F" connector, but it has a proper adapter that converts it to an RCA plug, as the transmitter has an RCA jack for RF out.
TIB
Hmm thinking this may be a 75 ohm set up and don't know if the Antenna would also work on a 50 ohm TX
Does the TX tune the frequency by dip switches?
Same tuning as FM 25B....TV "rabbit ears" with lead in cable is a center fed dipole and will have 1 ground element and one conductor element. Will work!
Had a 25B way back when and that's what I did....but the GAL-5 chip output kept blowing and I just got rid of it. Not because of the antenna but because of any static at all even when off will blow it.
To protect the GAL-5 you need a coil across the antenna to ground, not sure of the value, that will see a high impedence with the RF frequencies but will act as a surge protector if a static spark.
You have to keep taking the cabinet top off to change frequencies because the dip switches are on the circuit board.
Mark
that's right I forgot about that chip blowing all the time I don't think I would experiment with that particular transmitter it would just end up costing me a whole lot of money. The antenna though might work for the transmitter I have right now. That's what I was thinking about I was thinking whether or not it would be close enough to 50 ohms that way I could do it and then I could really get enough signal to where I need to reach and it would be above the awning so that the people in the parking lot could still hear me.
at least it's at least it's not one of those tune your dial analog transmitter where it would drift all over the place.
It'll handle 75ohms just fine, especially if you keep the run short.
Based on my personal experience, Rabbit Ear Dipole antennas can take 15 watts continuously for about 3 months before burning up the coax inside the antenna. I haven't had one burn up at 7 watts.
Hmm if I could save up it may be worth it for the Antenna and a back up TX. Had to help the step kids not lose power.
It's sold!
TIB
The 25B uses an F connector
Or at least the two i have use the F connector.
If I could get a easy to afford antenna I'd be set. Any other affordable ones that may work?
About Reply 10 of this thread:
... Based on my personal experience, Rabbit Ear Dipole antennas can take 15 watts continuously for about 3 months before burning up the coax inside the antenna. I haven't had one burn up at 7 watts.
That all may be true, but just to note that even severely mis-matched dipole or whip antennas with 7 or 15 watts (even just 25 milliwatts) of available transmitter power can radiate field intensities 3 meters away from them that FAR exceed the FCC §15.239 limit.