Handheld Scanner With Minimal Squelch Tail

[KR7CQ]

I need a handheld scanner with minimal squelch tail. I only need non-trunking analog capability. 100+ frequencies would be fine, civilian air band reception would be a plus. I have an agency on analog UHF and many scanners produce a long squelch tail at the end of transmissions from this system, but I know some scanners are better than others in that regard. Cost is a factor and an older model would be fine if it has tone decoding.

Suggestions for a model?

 

[mule1075]

BC125AT

 

[ChrisABQ]

Get a Pofung UV 82. Has 128 channel memories and with Chirp, you can adjust the squelch to almost eliminate the squelch tail. Can't beat it at $28. Covers VHF and UHF, no air band. https://www.amazon.com/Baofeng-UV-8...F8&qid=1516979547&sr=8-3&keywords=pofung+uv82

 

[jonwienke]

The Baofeng/Pofung radios scan about 3 channels per second. If the OP wants 100+ channel memories to scan they are a terrible choice.

BC125AT or BC75XLT would be far better choices, as they scan about 80 channel per second.

 

[KR7CQ]

I have a UV-5R, and the squelch tail is absurd on these frequencies, plus as was mentioned it's really slow scanning. I'm fine with the Uniden suggestions, but was hoping to maybe find a slightly older scanner on offer up or letgo that would fit the bill. I often see scanners on there for 20-30 bucks.

 

[jonwienke]

If you can find a used scanner, great. Pretty much anything will work better for scanning than a Baofeng.

 

[jaspence]

Scanner

Get the BC125AT. The Chinese radios are terrible scanners with no speed and do not cover military aircraft and others bands.

 

[ChrisABQ]

I love the negativity on this site, it was merely a suggestion and it works for me. Instead of bashing my suggestion, work at SUGGESTING other radios that will work for the OP instead of ganging up and pouncing on someone you don't agree with. Always the same issue on this site.

 

[jonwienke]

Instead of bashing my suggestion, work at SUGGESTING other radios that will work for the OP

We did--multiple suggestions to get a BC125AT, or look for a used scanner.

 

[jaspence]

ChrisABQ, he did mention airband would be a plus, and none of my Baofengs have that ability. I have over 50 HTs and several scanners, and my answer was based on using several different radios over the years. Other people also suggested the BC125AT.

 

[slicerwizard]

GRE scanners have fast squelch. Older models don't decode tones though.

 

[KR7CQ]

I appreciate all of the suggestions. Regarding GREs having a faster squelch vs. Uniden, that's an interesting take, and I do remember reading a chart from monitoring times years back that showed the PRO-2006 (one of my all-time favorites) having and amazingly quick squelch vs. pretty much anything else. I guess that trend continued over the years, even after the production switched to Chinese manufacturing. I was looking at a PRO-164 for a bit today, maybe I should consider that. But I have also played the BC125AT and love the big bold display too...choices choices.

 

[buddrousa]

It does not matter what RADIO / SCANNER you use if the radio shop turned on the Tone Squelch to transmit the tone the entire time the repeater is transmitting you will not be able to much about it. If the dealer only has the repeater transmit the tone squelch only as long as the signal is being received by the repeater then you will not hear a squelch tail on the repeater.

 

[mule1075]

It does not matter what RADIO / SCANNER you use if the radio shop turned on the Tone Squelch to transmit the tone the entire time the repeater is transmitting you will not be able to much about it. If the dealer only has the repeater transmit the tone squelch only as long as the signal is being received by the repeater then you will not hear a squelch tail on the repeater.

Um no.

 

[n1das]

GRE scanners have fast squelch. Older models don't decode tones though.

The problem with the fast squelch in those GRE scanners and all Uniden scanners is the squelch circuit is cursed with having too much hysteresis. It is still like that today in new scanners. I think they are designed to have 6 dB of hysteresis that the threshold, which I find to be way too much for my liking. I like having no more than about 2 dB hysteresis at the threshold, like what good commercial 2-way radios have. In all of my scanners (GRE and Uniden) owned during those years, I ended up modifying the squelch circuit to have just enough hysteresis to eliminate the tendency to chatter at the threshold but not so much to get in the way of reliably opening on a weak signal hovering just above the threshold.

I like the squelch time constant in my Uniden 396XT. It's around 22 ms. What I don't like is the squelch circuit has more hysteresis than I like. I would modify it in a heartbeat if I had schematic for the radio. The goal is not to mess with the time constant. I just want to optimize the amount of hysteresis at the threshold.

The squelch circuit is fast in just about all scanners on the market today. It makes me wonder exactly what the OP is complaining about. Is it a long time constant, i.e., a long burst of white noise at the end of a transmission or just a short tick at the end of a transmission? Is it too much hysteresis around the threshold and getting in the way? Some more information from the OP would help. As for older scanners with fast squelch, RadioShack models made by GRE are good but are still cursed with too much hysteresis.

 

[scannersnstuff]

GRE scanners have fast squelch. Older models don't decode tones though.

Ditto. I also believe that the squelch tail is longer on pl. enabled vs. dpl. enabled. The pl. tail is longer ?.

 

[n1das]

Ditto. I also believe that the squelch tail is longer on pl. enabled vs. dpl. enabled. The pl. tail is longer ?.

The PL and DPL time constants are much longer than the carrier squelch time constant is. You will only notice it if the carrier squelch is held wide open when decoding PL or DPL and no reverse burst is detected. With carrier squelch set and with PL or DPL decode enabled, you'll hear the end of the transmission with the same squelch tail as listening on CSQ. That's assuming the transmission heard isn't sending the reverse burst at the end of a transmission to help get rid of hearing any squelch tail.

Motorola normally has the carrier squelch held wide open during PL/DPL decode to take advantage of the decoder's ability to reliably open on a much weaker signal than any carrier squelch circuit can do. The decode threshold of a good PL or DPL decoder approaches the theoretical sensitivity of the receiver. The long time constant in the decoder is for stable operation and to handle mobile flutter. If a received signal does not transmit a reverse burst at the end of a transmission, you'll hear a long squelch tail due to the long time constant of the decoder. If the received signal has the reverse burst on the end of a transmission, you hear no squelch tail at all and the audio mutes just before the signal drops. The reverse burst on the end of a transmission is designed to mute receivers decoding PL or DPL before the signal drops to prevent hearing any squelch "crash" or "tail".

The carrier squelch time constant (aka "squelch tail") can't be too short otherwise the circuit won't handle mobile flutter very well.

 

[zz0468]

If you have the service manual, and the receiver isn't overly integrated, it's sometimes possible to modify the squelch circuit to change the time constants. Typically, immediately after the detector, audio is split into two paths. One goes to the audio amplifier chain, and one goes through a rectifier and filter. This is the noise source used to trigger the squelch.

You might see something like a diode followed by 1-10 uf capacitor. Change that capacitor to about a 0.1 uf, and you end up with a squelch that mutes with a click, not a noise burst. You also lose any hysteresis action, but I haven't noticed that to be a problem.

Mind you, this is based on older receivers, but it might still be used on an analog only scanner. Just a thought...

 

[n1das]

If you have the service manual, and the receiver isn't overly integrated, it's sometimes possible to modify the squelch circuit to change the time constants. Typically, immediately after the detector, audio is split into two paths. One goes to the audio amplifier chain, and one goes through a rectifier and filter. This is the noise source used to trigger the squelch.

You might see something like a diode followed by 1-10 uf capacitor. Change that capacitor to about a 0.1 uf, and you end up with a squelch that mutes with a click, not a noise burst. You also lose any hysteresis action, but I haven't noticed that to be a problem.

Mind you, this is based on older receivers, but it might still be used on an analog only scanner. Just a thought...

Many GRE designs used R=100k ohms and C=0.22uF to give a time constant of about 22 ms. Just a "tick" of a noise burst is all you get.

 

[zz0468]

Many GRE designs used R=100k ohms and C=0.22uF to give a time constant of about 22 ms. Just a "tick" of a noise burst is all you get.

There you go. That's exactly what I'm talking about. =)

Many years ago, while playing with things like simplex autopatch and vehicular repeaters, we reduced the time constant to as low as 1ms. You wouldn't even hear the click.