TK-790 Squelch Issues

billyfromhill · Jun 29, 2015

I just installed a TK-790 into my vehicle and I've been having some issues with the squelch. On channels with no PL/DPL I have to turn the squelch up to 10 in order to get them to squelch, otherwise I hear static all the time.

Additionally, on channels with a PL/DPL, the busy LED is constantly on/flickering unless the squelch is set above 5-6. These channels do not break squelch at any level (including 0 and 1) except when receiving. Any ideas? All of my channels except two are narrowband.

mmckenna · Jun 29, 2015

billyfromhill said:
I just installed a TK-790 into my vehicle and I've been having some issues with the squelch. On channels with no PL/DPL I have to turn the squelch up to 10 in order to get them to squelch, otherwise I hear static all the time.

Right. With no PL/DPL that's the way it works. Your radio is running in carrier squelch mode.
What were you expecting it to do? Is it picking up interference from the vehicle? Does the need for a higher set squelch go away when the vehicle isn't running?

billyfromhill said:
Additionally, on channels with a PL/DPL, the busy LED is constantly on/flickering unless the squelch is set above 5-6. These channels do not break squelch at any level (including 0 and 1) except when receiving. Any ideas? All of my channels except two are narrowband.

Again, that's the way it's supposed to work. The flickering "Busy" LED just looks at the traffic on the channel. The radio is hearing something, maybe even just static, but it doesn't have the right PL/DPL to open the speaker.

You could set up an "off hook" setting on your mic. It's pretty common to set these up so the RX PL/DPL tone is active when the microphone is on the hook, and defeated when you take the mic off the hook.

DJ11DLN · Jun 29, 2015

Sounds like your vehicle is making a lot of RF noise. Some newer ones are notorious for this. There are some filter options but you'll have to find the exact source of the interference so you'll know what to do about it.

ramal121 · Jun 30, 2015

Pull the coax off the back of the radio. If the static (or busy light) goes down to 0 or one on the radio's squelch, then you just have a noisy environment where the radio lives. Not much you can do unless you want to hunt down the source of the noise. If need be, the tight and open settings of the squelch can be adjusted in the test section of the program software.

billyfromhill · Jun 30, 2015

mmckenna said:
Right. With no PL/DPL that's the way it works. Your radio is running in carrier squelch mode.
What were you expecting it to do? Is it picking up interference from the vehicle? Does the need for a higher set squelch go away when the vehicle isn't running?

Again, that's the way it's supposed to work. The flickering "Busy" LED just looks at the traffic on the channel. The radio is hearing something, maybe even just static, but it doesn't have the right PL/DPL to open the speaker.

You could set up an "off hook" setting on your mic. It's pretty common to set these up so the RX PL/DPL tone is active when the microphone is on the hook, and defeated when you take the mic off the hook.

I guess I expected the CSQ channels to behave differently since this is my first mobile radio. On all my portables I don't have the issue where CSQ channels are opening up to static. I believe I have my radio set to decode PL/DPL while off-hook, but only scan while on-hook. Does the mic holder need to be grounded?

I guess the squelch issue is kind of a bummer since my cheapo BC355N scanner is receiving better and clearer than the mobile.

ramal121 said:
Pull the coax off the back of the radio. If the static (or busy light) goes down to 0 or one on the radio's squelch, then you just have a noisy environment where the radio lives. Not much you can do unless you want to hunt down the source of the noise. If need be, the tight and open settings of the squelch can be adjusted in the test section of the program software.

I'll have to give this a try. Ideally the busy light should never be on except with receiving traffic correct?

The radio is installed in my center console with power/ignition sense, speaker wires, and coax all run under the console to up under the dash where they then split apart to opposite sides of the vehicle. I wonder if I should try separating the power and coax wires more.

Charlie · Jun 30, 2015

You mention that all but two of the channels are narrow band...

I vaguely recall that the Kenwood -90 series radios require a re-tuning or other adjustment for narrow band. They will exhibit the symptoms you describe if that has not been done. Disregard this suggestion if you have already had a shop do this for you.

billyfromhill · Jun 30, 2015

Charlie said:
You mention that all but two of the channels are narrow band...

I vaguely recall that the Kenwood -90 series radios require a re-tuning or other adjustment for narrow band. They will exhibit the symptoms you describe if that has not been done. Disregard this suggestion if you have already had a shop do this for you.

I have not had it re-tuned. The previous owner used the radio in receive-only. Would this be something that I can just take the radio in for or would they have to tune the radio in my vehicle with my antenna?

Avery93 · Jun 30, 2015

This is a known issue with older 90 series mobiles, which did not have the narrowband squelch aligned correctly at the factory. You can fix this yourself (at some risk, see below) by changing the squelch values in the "Panel Test" or alignment menu, as described in this video. It's best to do this with a service monitor, but I have aligned several FS and regular firmware 790's using only the values in the video, and have had no problems. The video only mentions FS/CDF firmware radios, but I have encountered the same problem on older 790's with regular firmware as well.

Do not change any values except SQL TIGHT and SQL OPEN! Also write down the previous values before overwriting them.

TK-790 Squelch Issues

billyfromhill

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mmckenna

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DJ11DLN

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ramal121

Lots and lots of watts

billyfromhill

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Charlie

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billyfromhill

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Avery93

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