Making a 33MHz loaded base into 46MHz

[SlipNutz15]

I have an Antennex 30-35 loaded base antenna with a rather long whip on it. I know the loaded base is made to make up for the length the whip really needs to be. How long should the whip be shortened to equal a 46MHz antenna whip? This is for RX only.

I'm not good with the calculations and I know there's someone out there that can whip up a length pretty quick. Any info would be greatly appreciated.

 

[fineshot1]

I have an Antennex 30-35 loaded base antenna with a rather long whip on it. I know the loaded base is made to make up for the length the whip really needs to be. How long should the whip be shortened to equal a 46MHz antenna whip? This is for RX only.

I'm not good with the calculations and I know there's someone out there that can whip up a length pretty quick. Any info would be greatly appreciated.

Well you did not mention the model number of the antenna but chances are that the loading coil would have to be swapped to the correct one as well so you are probably just spinning your wheels.

You would most likely be better off purchasing the correct model for the 46mhz freq range.

 

[Fast1eddie]

If your application is receive only, the antenna should work fine as is, assuming the coax and connector is in good shape. If the antenna is already mounted, find a steady signal to monitor. Using the radio's S-Meter, cut the whip a quarter inch until the reading peaks. The whips and coils are fairly broadbanded and easy to modify.

Ed

 

[SlipNutz15]

Ed, the frequency I want to zone in on is 46.060 which is my home county's frequency (Juniata County, PA). Also, Cumberland County and Union County use this same freq to dispatch off so I don't really have a "non-strong" signal to base everything off because Cumberland is just over the mountain and their 46.060 is tied to their TRS which is loud and strong no matter what. The scanner doesn't really have a signal strength meter on it that is really dependable. I guess I'll just go with what I cut it at and see how it works, if nothing else I can always try to buy a true 46MHz band antenna. Free is free though, figured I'd try it first.

If I got the model number of the antenna I have on my vehicle, would that help anyone at all with the whip shortening length?

 

[prcguy]

A full 1/4 wave whip for 46MHz would be about 24" shorter than for 33MHz but trimming a loaded antenna may not follow the exact same ratio.

Many loaded low band antennas come with 39" whips and that might leave you with about a 15" long whip after cutting for 46MHz. That's not good, I suggest you find a correct antenna for 46Mhz.
prcguy

 

[nd5y]

If I got the model number of the antenna I have on my vehicle, would that help anyone at all with the whip shortening length?

If you had the model number you could see if the manufacturer had a instructions or a cutting chart on their web site or their customer support might be able to tell you how long to cut the whip.

 

[rvictor]

Since you're dealing with strong signals, it may work fine just as it is. Give it a try.

Dick

 

[SlipNutz15]

Ok, here's the information from the base of the antenna surrounding the center conductor:
Top: C30S
Left: 151
Right: 215
Bottom: 30-35 MHz DC GRN 1/4