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RS Pro-404 / GRE PSR100 handheld

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#1
For this review, I used a Radio Shack Pro-404, although the GRE PSR100 is nearly identical.

These are analog-only, conventional channel units, and their upper frequency coverage tops out at 512 mhz. Pc-programmability is a plus, (no alpha tags) along with spectrum-sweeper, and weather alerting using FIPS codes. The simplified interface is a welcome to newcomers to the hobby, although the smart ones will do their homework in the forums and databases to make sure that there are conventional systems left in their area. For the time being, generic airband, marine, railroad etc should be no problem.

The 404 I tested had amazingly loud audio - louder than any other handheld I've encountered lately. The high-end was a bit harsh for my tastes, although in a very noisy environment, this might lead to enhanced intelligibility. You can push it into distortion, but you'll know immediately as the difference between loud and distorted is a knife-edge difference on the volume pot. Some typical GRE hiss was heard from the audio amp.

The major issue for those in metropolitan areas like myself, is that the scanner uses only a dual-conversion setup with a first IF of 10.7 mhz. I really thought that went away in the 90's, as other manufacturers in this price range have been using triple-conversion. Typically, the dual-conversion means that image frequencies 21.4 mhz away from your intended station can be mixed in.

In my case, a local college security team on a 460 business band freq landed right on top of my 483 mhz Sheriff's system. At first, I was amazed at the lack of professionalism on the Sheriff's channel - something I'm definitely not used to so I tuned down 21.4 mhz away and sure enough, the college team was on their assigned frequency. Airband was the same, as I was able to hear the data bursts from an amateur radio packet system invading my local airport tower. Surely, a ham should know not to interfere with an aircraft tower! Nope - the dual-image 21.4 mhz away was the culprit.

One would think that you might be able to smother this effect with an attenuator, (also NOT my preference - it is like using a sledgehammer to pound in a finishing nail), but the 404 does not have an attenuator.

I also noted that the sensitivity in airband (118-136) was a bit down from my other units - and the specs revealed that it is least sensitive in this band.

Amateurs wanting to use it for 440 UHF monitoring may find themselves off frequency if their area has switched to 20khz spacing - with the standard 12.5 khz spacing of most scanners, you might zoom right past an active system while searching. If your area has made a switch to 20khz spacing, just put the system into a memory, knowing that the scanner will be a bit off frequency.

Overall, I really like the loudness of the audio when not cranked into distortion (although I wish manufacturers would pay attention to the high-end and amplifier hiss), and would have kept it, even with the lower sensitivity on the airbands, but the dual-conversion IF circuitry let me down, so away it went.
 
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Bay Shore, NY
#3
Really appreciate you taking time to share your review of the radio - that is the beauty of this site, fellow hobbyists sharing thoughts, tips, etc. Thanks for your contribution!!

Bob
 
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#4
Thanks!

It is getting kind of lonely in here - this isn't a review forum just for me!

I am by no means an expert reviewer either...
 
Joined
Jun 18, 2012
Messages
40
Location
Columbia,SC
#6
For this review, I used a Radio Shack Pro-404, although the GRE PSR100 is nearly identical.

These are analog-only, conventional channel units, and their upper frequency coverage tops out at 512 mhz. Pc-programmability is a plus, (no alpha tags) along with spectrum-sweeper, and weather alerting using FIPS codes. The simplified interface is a welcome to newcomers to the hobby, although the smart ones will do their homework in the forums and databases to make sure that there are conventional systems left in their area. For the time being, generic airband, marine, railroad etc should be no problem.

The 404 I tested had amazingly loud audio - louder than any other handheld I've encountered lately. The high-end was a bit harsh for my tastes, although in a very noisy environment, this might lead to enhanced intelligibility. You can push it into distortion, but you'll know immediately as the difference between loud and distorted is a knife-edge difference on the volume pot. Some typical GRE hiss was heard from the audio amp.

The major issue for those in metropolitan areas like myself, is that the scanner uses only a dual-conversion setup with a first IF of 10.7 mhz. I really thought that went away in the 90's, as other manufacturers in this price range have been using triple-conversion. Typically, the dual-conversion means that image frequencies 21.4 mhz away from your intended station can be mixed in.

In my case, a local college security team on a 460 business band freq landed right on top of my 483 mhz Sheriff's system. At first, I was amazed at the lack of professionalism on the Sheriff's channel - something I'm definitely not used to so I tuned down 21.4 mhz away and sure enough, the college team was on their assigned frequency. Airband was the same, as I was able to hear the data bursts from an amateur radio packet system invading my local airport tower. Surely, a ham should know not to interfere with an aircraft tower! Nope - the dual-image 21.4 mhz away was the culprit.

One would think that you might be able to smother this effect with an attenuator, (also NOT my preference - it is like using a sledgehammer to pound in a finishing nail), but the 404 does not have an attenuator.

I also noted that the sensitivity in airband (118-136) was a bit down from my other units - and the specs revealed that it is least sensitive in this band.

Amateurs wanting to use it for 440 UHF monitoring may find themselves off frequency if their area has switched to 20khz spacing - with the standard 12.5 khz spacing of most scanners, you might zoom right past an active system while searching. If your area has made a switch to 20khz spacing, just put the system into a memory, knowing that the scanner will be a bit off frequency.

Overall, I really like the loudness of the audio when not cranked into distortion (although I wish manufacturers would pay attention to the high-end and amplifier hiss), and would have kept it, even with the lower sensitivity on the airbands, but the dual-conversion IF circuitry let me down, so away it went.
Thanks for your post.For me,I find your post to be informative.
 
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#8
404 revisited for airband use

Despite my problems with dual conversion, and the lower sensitivity on airband, I missed the generally good audio so much I purchased it again just for that reason.

This one is dedicated mostly to airband monitoring - and I enjoy good audio when doing so. I have been through many other GRE's (and Radio Shack rebadges), along with Uniden's, and still this is my favorite handheld to listen to when doing airband.

Yes, in my rf-jungle location, searching is about useless due to the images about 21.4 mhz higher than the primary band on vhf, but I program airband freqs into memories and scan, rather than search with this radio. Fortunately, the 2-meter amateur images up at around 146mhz don't interfere with my airband channel memory frequency assignments (so far).

The sensitivity issue is easily cured by using a more efficient antenna. The oem duck supplied aggravates the image issue as it is resonant in the 2m amateur band. (Uniden oem ducks are resonant near 158 mhz). There are many ways to simply improve the oem duck, and of course my favorite is to use a telescopic. But, while it is not a perfect solution, the Icom FA-B02AR duck is firmly planted on the 404 now due to it being resonant in the civil airband, and also narrow in response. It is not a perfect cure, but it helps. Everyone has their favorite oem duck replacement, this just happens to be mine for civil airband.

I think the stars aligned well enough so that the mix of speaker frequency response, audio amplifier response, and case acoustics provides an overall response that is joy to my ears. And unlike the volume control being easily driven into distortion later in the pot travel when listening to FM modulation, the AM modulation of airband monitoring seems to be not as critical with a little more pot-travel leeway - although you can still drive it into distortion if you really crank it.

Sure, the audio could be even better to the audiophile. Maybe a *tad* less high-end, and at times the plastic case can seem a bit tubby on the low. Sure wish the audio amp would cut completely out when squelched and have even more power. Yet still, overall the audio on this radio justified a re-purchase due to my lust for good scanner audio.

No, it is not my main airband radio and is certainly not perfect by any means - but it is back in use as the most pleasant one to listen to so far. I think other manufacturers should put one on their desk and see what went right in the audio department on this model, and improve upon it even further.
 
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#9
Update: The great audio mentioned in the above post is for AM airband monitoring. FM is a different story, and to my ears a bit shrill but usable.
 
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#10
Pro-404 Airband antenna

Just a quick note to airband monitoring enthusiasts using the Pro-404. I have developed an easy to use *tuned* airband antenna that really helps with the dual-conversion image problem coming from amateur 2m, 150mhz pagers, and other carriers.

You already have one and don't know it. You can make it in a matter of minutes:

http://forums.radioreference.com/build-your-own-antenna/261896-vhf-airband-mod-rs-uniden-ducks.html

It sure is ugly - but can cure much of the frustration of open squelch coming from mild to moderate image frequencies when monitoring airband.
 
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