PSR600 VHF issue

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FireDawgEMT22

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I am having an interesting issue on a single VHF frequency on my PSR 600.

I had a Pro 433 with a RS 20-176 antenna and had about 50 feet of RG58 cable, and I was able to get all the VHF frqs no problem.

I then ugraded to the PSR600 and kept the same antenna and moved it up about 20 feet higher and am running 60 feet of RG6. I was having issues getting most VHF signals, Very garbled, sounded very weak. So I applied the Attenuator and they all come in crystal clear now...except 1. The one is transmitted from about 30 miles away. Without the attenuator on the signal shows full signal stregnth reading, but no "S". With the attenuator on it drops to about 1 bar, and if I am monitoring it I can pick up the signal very scratchy, but it when scanning it will not stop on it for traffic, but at times it will stop on it for a brief second, like it broke the squelch and then go back to scanning.

Is the scanner getting too much signal? I highly doubt I am too far away because it is a VHF signal, and it is only 30miles, and I got it just fine before with my pro 433 and have raised my antenna since then.
 

N8IAA

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Who, what, and where is the frequency tied to? Have they narrow banded their frequency? They don't have to change the frequency to go narrow band. Thirty miles in your location isn't a lot, but if they narrowed down the width of the frequency, it will be at lower power.
Larry
 

Mojaveflyer

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PSR-600 Reception

I had problems with my PSR-600 until I bought a FM trap (88 - 108 MHz) and placed it in line to reduce intermodulation. It made the radio act like a new one... The specific VHF traffic I was having problems with were in the railroad band, 160 - 161 MHz. I took a piece of coax, put a "F" connector on one end for the FM Trap and a BNC connector on the other end. Relatively simple fix... What specific frequency are you having trouble with?
 

FireDawgEMT22

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It is the fire dept disp freq for one of my jobs/volunteer depts. It is 154.3100, I get 154.2200 and 153,8900, and 154.1000 just fine with the attenuator applied, the 154.1000 is being broadcast from relatively the same distance in the opposite direction. And no they have not yet narrowbanded. I was thinking it was an intermodulation issue, just thought it was odd that the attenuator removed that issue on all the other VHF frequencies I listen to but that one.
 

FireDawgEMT22

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Another interesting piece of info is that when I had a different setup for my antenna (same location) I had 25 feet of RG58 going to a splitter and then from the splitter had another 50 feet of RG58 going to my scanner (I know I know lots of loss) but I was able to get the 154.3100 signal perfectly.

So that makes me really think it is some overloading on scanner now, and I looked at the FM traps and filters, but unless I am looking at the wrong thing, they say they need tuned and I dont know how or what I would tune it to to get rid of the overload.
 

FireDawgEMT22

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I threw a FM trap 99-108mhz. I shut off the attenuator on all but 2 VHF freqs (153.8900, 154.235, and 154.1) I had to leave the attenuator on on those because I was still getting singal (NOAA on the 154.1000 and just something 2 bars worth that was breaking the squelch on the other 2)

The original 154.3100 that I was having problems with went from 4-5 bars of signal with no real signal (no S) went down to nothing, lets see if the dispatch info comes through now (just heard dispatch on the 153.8900 so that works)

Thanks for the advice, hope this works.

Edit: Working great, comes through clear and loud on the previously problematic VHF channel.
 
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Nasby

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Two questions: 1) Do you guys live in an area with lots of strong, nearby signals/transmitters?
2) Where did you get the FM traps?
I'm having similar problems but I live in the country.
Thx!!
 

FireDawgEMT22

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I did a search on that fcc website and found about a dozen towers within 5 miles of me. I am in the city of Toledo Ohio. And i got the radio from radio shack. 8 bucks. Just did a search on the rs website for fm trap
 

mikebennett

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Sherman, TX
I am having an interesting issue on a single VHF frequency on my PSR 600.

I had a Pro 433 with a RS 20-176 antenna and had about 50 feet of RG58 cable, and I was able to get all the VHF frqs no problem.

I then ugraded to the PSR600 and kept the same antenna and moved it up about 20 feet higher and am running 60 feet of RG6. I was having issues getting most VHF signals, Very garbled, sounded very weak. So I applied the Attenuator and they all come in crystal clear now...except 1. The one is transmitted from about 30 miles away. Without the attenuator on the signal shows full signal stregnth reading, but no "S". With the attenuator on it drops to about 1 bar, and if I am monitoring it I can pick up the signal very scratchy, but it when scanning it will not stop on it for traffic, but at times it will stop on it for a brief second, like it broke the squelch and then go back to scanning.

Is the scanner getting too much signal? I highly doubt I am too far away because it is a VHF signal, and it is only 30miles, and I got it just fine before with my pro 433 and have raised my antenna since then.
I had the same problem with strong signals overloading the radio and even missed a lot of transmissions because of it. If you turn the attenuator on it helps but then you'll miss weaker signals. I ended up switching my 600 out for another 996XT which doesn't have that issue.

Mike
 

FireDawgEMT22

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I just put in the FM trap and it fixed everything. Well never give up my 600. Highly superior to the uniden from my experience with them
 

k7ng

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Actually, depending on actual signal levels you may not be completely out of the woods yet, firedawg. There is a 3rd-order intermod product from 154.100 and 153.89 that falls directly on 154.31. You wouldn't hear this unless both 154.1 and 153.89 were transmitting at the same time. You would hear this as distorted audio of both channels mixed together. It might not be affected by the attenuator of your scanner, as the production of this product might not come from the circuitry of your scanner but other sources. If 154.31 is using tone squelch and the tone is different from both 154.10 and 153.89 then if you enable CTCSS on 154.31 you might never hear the intermod product. If either of the 'interferer' channels use the same tone as 154.31 the CTCSS will NOT prevent the intermod from being heard.

The stronger the two signals are (154.100 and 153.89) the higher the possibility of this occurring.
The likelihood of having intermod problems also increases when there are lots of strong signals entering your scanner (TV and FM for example) that DON'T directly ggenerate audible signals but just 'beat up' the front end of the scanner - which is why the trap and/or the attenuator fix things.

If the problem never recurs, well, you're in great shape!
 

FireDawgEMT22

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I dont forsee a problem with the 3rd order because as you said the tone squelch. 154.31 uses 107.2, 154.1 uses CSQ, and 153.89 uses 156.7. I have the CTCSS programmed in for all of them so while yes it may be floating out there, I shouldnt hear it.

I am just amazed how much clearer ALL my VHF comes in with no attenuator activated since adding in this little black box called the FM trap. I never got big into all these little details with scanning, for me it used to be either it worked or I just assumed I was too far away. As I learned more about it, I have realized that I should have been getting more than I was before and through my trials and tribulations with antennas and feed lines and traps, etc I am getting so much more traffic now.
 

KD8FSJ

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I had the same issue. If I remember right my fix was to add the ATT to only the frequencies having the most difficulty. The easiest way to change this was in the programming software. If you are just hitting the ATT on the scanner itself you may be in the global settings and applying ATT to everything rather than the offender(s).

Paul

I am having an interesting issue on a single VHF frequency on my PSR 600.

I had a Pro 433 with a RS 20-176 antenna and had about 50 feet of RG58 cable, and I was able to get all the VHF frqs no problem.

I then ugraded to the PSR600 and kept the same antenna and moved it up about 20 feet higher and am running 60 feet of RG6. I was having issues getting most VHF signals, Very garbled, sounded very weak. So I applied the Attenuator and they all come in crystal clear now...except 1. The one is transmitted from about 30 miles away. Without the attenuator on the signal shows full signal stregnth reading, but no "S". With the attenuator on it drops to about 1 bar, and if I am monitoring it I can pick up the signal very scratchy, but it when scanning it will not stop on it for traffic, but at times it will stop on it for a brief second, like it broke the squelch and then go back to scanning.

Is the scanner getting too much signal? I highly doubt I am too far away because it is a VHF signal, and it is only 30miles, and I got it just fine before with my pro 433 and have raised my antenna since then.
 

FireDawgEMT22

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I had the same issue. If I remember right my fix was to add the ATT to only the frequencies having the most difficulty. The easiest way to change this was in the programming software. If you are just hitting the ATT on the scanner itself you may be in the global settings and applying ATT to everything rather than the offender(s).

Paul
I had the attenuator set, but the problem was with the 154.3100 the attenuator was too much. And I was getting no signal on it. And the attenuator was being set to individual objects not globally. The FM trap allowed me to remove the attenuator from all of the VHF frequencies.
 

Tech792

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If the built-in attenuator is too much, you might want to try this. I purchased a 1 db att on Ebay for about $9 and it made a world of difference. Its a BNC M/F just connects in-line. I'm not in an extreme overload area but it was an occasional problem. But the 1 db ATT did the job for me. I no longer need the built-in ATT on the freqs I was having issues with and don't notice any reduction in weaker signals.

PASTERNACK 7000-30, 1 WATT TO 2 GHZ BNC 30 dB ATTENUATOR, 50 OHM | eBay
 

gewecke

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I had a similar problem with strong overload on a GRE from 2 nearby 400' towers within line of sight. I've almost completely cleared up the overload and intermod problems just by experimenting with different inside and outside antenna combo's, and almost no use of the ATT now, while still being able to hear most UHF repeater systems 25 miles away.

73,
n9zas
 

DaveH

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If the built-in attenuator is too much, you might want to try this. I purchased a 1 db att on Ebay for about $9 and it made a world of difference. Its a BNC M/F just connects in-line. I'm not in an extreme overload area but it was an occasional problem. But the 1 db ATT did the job for me. I no longer need the built-in ATT on the freqs I was having issues with and don't notice any reduction in weaker signals.

PASTERNACK 7000-30, 1 WATT TO 2 GHZ BNC 30 dB ATTENUATOR, 50 OHM | eBay
A 1 dB attenuator would have next to no effect. As it turns out, this is a 30dB attenuator
with 1W power handling. This is probably higher than the PSR600 global ATT (would need
to check specs). In any case you don't get the choice on a channel-channel basis with
an inline attenuator. So.. with 30dB I'm scratching my head as to why there is no effect on
weaker signals, or why it should work better than the internal one.

Dave
 

Boatanchor

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Unfortunately, the PSR600 does tend to overload very easily on VHF when using 'decent' base antennas.
I have both the PSR600 and the 996XT and the 996XT doesn't suffer from any overload on the same base discone antenna. As mentioned, the PSR attenuator fixes the problem but if you, like me, listen to weak signals, the attenuator kind of defeats the purpose of the scanner.

The 130mhz aircraft band is virtually useless on my PSR600, unless I activate the attenuator.

It iseems the 996XT has much better selectivity on most, if not all bands and to me, this is easily worth the extra $100 in cost.
 

Mojaveflyer

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PSR-600 Intermodulation

Two questions: 1) Do you guys live in an area with lots of strong, nearby signals/transmitters?
2) Where did you get the FM traps?
I'm having similar problems but I live in the country.
Thx!![/QUOTE]

I live on the north side of the Denver, CO , Metro Area. I bought my FM Trap at Radio Shack along with the necessary connectors. I found the worst intermod on the northwest side of town.
 

Halfpint

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I live on the north side of the Denver, CO , Metro Area. I bought my FM Trap at Radio Shack along with the necessary connectors. I found the worst intermod on the northwest side of town.
Ah, yes! From around 88th Ave North to about 124th Ave along I-25 is what can only slightly charitably called "RF Hell". Back in the '70s one either had to have `tones' set and sometimes even an attenuator in line to get through there and be able to keep hearing what one wanted to hear. Fast forward to the inception of the DTRS and all it's `teething pains' and cell sites and other related sites and there were times when even filters and attenuators couldn't `cut it' at times. Since I, now, don't make it down that way all that much I haven't really `tested' my PSR-800 through that area but, I wouldn't be too surprised if it might still call for some sorts of `tweaks', like my PSR-500 occasionally did, from time to time. Especially if one has to live in that area or travel through a lot.
(There are times when it seems that one has to just rely on pure unadulterated `Voodoo' and hope for the best. {WAN GRIN!})
 
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