Mobile Antenna to Base Adapter

[Dewey]

I am seriously thinking of getting an adapter to convert a mobile antenna to a base antenna. I don't care for discones or "large" base antennas, and I think the MONR33 would make a nice base antenna. Is there a rule of thumb that I will have to follow for the length of the radials on the base mount?

Thanks,
Dewey

EDIT: I also know the radials on some bases point downward like a cone while others point straight out at 90 degrees. Does this make a difference?

 

[SAR923]

The MONR33 is not the choice if you don't want a "large" base antenna. I wish I still had the rooftop mount with me still but it got lost in moving and all I have is the whip section. The rooftop mount had four radials that extended downward at about a 45 degree angle. While I don't know the exact measurments, they were at least four feet long. I'd seriously consider looking at a Radio Shack 20-176 if you want a compact base antenna.

 

[Dewey]

The MONR33 is not the choice if you don't want a "large" base antenna. I wish I still had the rooftop mount with me still but it got lost in moving and all I have is the whip section. The rooftop mount had four radials that extended downward at about a 45 degree angle. While I don't know the exact measurments, they were at least four feet long. I'd seriously consider looking at a Radio Shack 20-176 if you want a compact base antenna.

Thanks for the heads up on the size of the MONR33 base. I didn't realize the radials made it that big! I am currently using a 20-176 in house, but when I move to outside the house, I want to try to get a little more performance without increasing the size too much. I'm also looking at the Mon-3 (http://www.parelectronics.com/ant_scanner.htm). I don't see a lot about it out there, but those two reviews that I did find claimed it to be a good performer. The owner of the company told me that they have temporarily suspended their amateur productions to give full service to the military, and that they'll resume on the 15th. I might wait till then and go with that antenna.

Thanks again,
Dewey

 

[SAR923]

I've read some mixed reviews on the Mon-3. First, it's been out of stock at dealers for almost a year so restarting production may or may not be true. It's pretty expensive for what you get although it is apparently well made. The radials are 38 inches, which is considerably larger than the 20-176. Users who have compared to Mon-3 to the 20-176 say it's better at 800 and, for some reason, low band, but not as good on VHF or UHF. I guess it all depends on what you listen to most. If it's VHF or UHF, I don't think you're going to find a much bettter antenna than the 20-176. I'd consider putting the money into some good coax first since you need that anyway and see if the 20-176 really needs replacement.

 

[wannabescannist]

EDIT: I also know the radials on some bases point downward like a cone while others point straight out at 90 degrees. Does this make a difference?

Angling the radials downward increases the antenna's impedance...I think it's the higher (elevation-wise) you go off the ground (with respect to wavelength), the lower the impedance of the antenna. Angling them downwards tries to get the antenna's impedance back up to 50 Ohms so that it's matched with the rest of your system.