Radio Shack Center-Loaded Telescoping Scanner Antenna

[KK4SYW]

I was wondering how those of you that have used a Radio Shack Center-Loaded Telescoping Scanner Antenna liked it as a scanner antenna. I am planning on using it with my Radio Shack Pro-404 Scanner.

 

[oft]

Which RS part #?

20-006 (from 25 MHz to 1296 MHz)

or the 20-551 (from 25 MHZ to 512 MHZ) that now has a 90° BNC connector - previously, it was known as the 20-161 when it had the old motorola 90° car radio type antenna connector?

The 20-006 did alright from 118 MHz to the 450 MHZ range but I found it weak in the low VHF band (42MHz) and the 950 band. It performed ok in the 850 MHZ area when adjusted per the instructions.

The 20-551 / 20-161 did very good throughout the frequencies it was rated at.

 

[KF4ZTO]

If you adjust it per the instructions, its a pretty good antenna. I've had a couple of them over the years and always had the issue of the top section getting bent and basically ruining the antenna. However, VHF-low performance is actually good when the antenna is completely extended.

If you're planning on listening to anything from VHF-air and up, its a great antenna (and you don't need to extend it all the way).

If you're just listening to VHF-high and UHF, there are better options out there in the form of flexible antennas. What frequency band(s) are you going to be listening to most often?

 

[KK4SYW]

Thanks for the replies. I am mostly going to listen to local police and 2 meter ham band.

 

[haleve]

I see that your local police departments are on UHF & it sounds as though you already have that antenna, if not this would probably be a better choice as the RS antenna will make your scanner top heavy, not a good thing if it tips over, good luck.

Diamond RH77CA Amateur HT Antenna

 

[nanZor]

On some frequencies, (such as airband or vhf-hi) you may get better reception by shorting out the loading coil and using it as a plain telescopic. You can do this by pushing the element just above the coil back down inside the coil by about a quarter-inch or so until you feel some resistance at the internal shorting points.

 

[krokus]

Assuming your local PD is on UHF, as noted by haleve, you could look at a ham dual-band antenna. I have used one before, and it works pretty well for the nearby public safety frequencies.

I have had one of the RS telescoping whips, and might still have it in a box, somewhere. It was decent, but it is a bit unwieldy. The MFJ-1717 series has done well for me, and is much more forgiving of life.
MFJ Enterprises Inc.

 

[nanZor]

On some frequencies, (such as airband or vhf-hi) you may get better reception by shorting out the loading coil and using it as a plain telescopic. You can do this by pushing the element just above the coil back down inside the coil by about a quarter-inch or so until you feel some resistance at the internal shorting points.

UPDATE for airband usage on dual-conversion scanners like the Pro-404!

The main resonant point of the RS telescopic when fully extended is about 45 mhz as seen on a Comet CAA-500 analyzer. There is also another narrow and less-efficient resonant point at 128 mhz when fully extended. But this basically means that there is no reason for the coil to be inline, and the shorting trick mentioned above to remove the coil results in a better airband signal.

However, having that less-efficient resonant point when fully extended for airband use also results in a large amount of off-frequency reactance which may really help out when using dual-conversion scanners like the original posters Pro-404.

Even though I'm not a fan of dual-conversion scanners, I recently purchased a Pro404 (aka GRE PSR100) for a specialized use, and found that when fully extended, the RS telescopic whip on airband acted very much like an airband passband filter with perhaps a 3-6db insertion loss due to the coil reactance.

Pagers near 153mhz, NOAA wx, even FM broadcast were attenuated to a degree (as measured on my Icom R20). Flamethrower-strong image signals still made their way through, but a vast majority of annoying out-of-band squelch-breakers went away.

In the end, good scanners with triple conversion may benefit from the coil-shorting technique. Dual-conversion scanners dealing with image interference may benefit from leaving the whip fully extended with the lossy coil inline - a slight decrease in wanted airband signals is compensated by also attenuating the out of band image carriers more than a standard whip does.

 

[joeuser]

Is anyone aware of testing done on this antenna that shows segment extensions & performance on certain freq ranges?