Laird UHF mobile antennas

[lu81fitter]

I have 2 Laird UHF mobile antennas. One is B 4503 and the other is a B 4505CS. The coil looks to be the same from the outside. I was wondering if I could interchange the whips on these? The one with the spring is about 8-9 years old, and I was told that an aging antenna with a spring could cause decreased performance. Anyone have any ideas?

 

[mmckenna]

From the Laird documentation I have it looks like it probably will.

The B4503 is a 3dB gain 5/8ths wave antenna.
The B4505CS is a 5dB gain 5/8ths over 5/8ths wave co-linear antenna.

Since the are both 5/8ths wave (4503 is and the 4505 is a stacked 5/8th's) it should work.

Double check to see on the underside if their are any markings on the coil. See if they match.

Springs can create noise as they move. Keep in mind that the spring is a part of the radiating element, and if you remove it, you have to make up it's length. You can order replacement parts from Laird.

 

[lu81fitter]

None of the numbers match other than saying that they are used for 450-470 band. I only use these antennas for RX, so a little toying is not the end of the world. I can always just switch them back. I noticed that I receive a bit better with the lower gain antenna, which made me wonder about the spring and the connections.
Also, mmckenna, I like the magnet statement. After years of messing with magnet mounts, I finally drilled one in, and it works great. Not looking back.

 

[mmckenna]

None of the numbers match other than saying that they are used for 450-470 band. I only use these antennas for RX, so a little toying is not the end of the world. I can always just switch them back. I noticed that I receive a bit better with the lower gain antenna, which made me wonder about the spring and the connections.

One of the numbers on the base is a date code, so unlikely it'll match. The other one should be a product code of some type. Laird documentation mentions this, but doesn't state which one is which.

But, you are correct, for receiving, it isn't an issue. Find something that works.
There are cases where a lower gain antenna can outperform a higher gain antenna, so that's not unusual. However, if you suspect damage, go with your gut.

Also, mmckenna, I like the magnet statement. After years of messing with magnet mounts, I finally drilled one in, and it works great. Not looking back.

Thanks. Just a good natured jab at the magnet mount crowd. I do one one mag mount, but I only use it for testing. All my mounts are permanent. Looks better, works better, and adds peace of mind.