TK-790/TK-890 Narrow Band Tuning

[car5le]

I need some direction on adjusting the TK-790/TK-890 dual band radio for narrow band use. I know there are two ways, either by front panel, or by computer. Either way or both way would be good.

I do have all the legitimate software and cables.

Any help is appreciated!

 

[SCPD]

w/n

In KPG 44D, double click on the ch number on the left select narrow or wide. repeat for each channel you need to change.

 

[car5le]

That part I've done. The problem is tuning. I need to "tighten' the squelch and CTCSS. That can only be done from the Front Panel Tuning or the Test Mode in the software. I can get to the front panel tuning, but need a little direction. In the KPG-44D I cannot get the Test Mode under the Program Menu become active. I would prefer to adjust the tuning from the software.

 

[ramal121]

To get to the test mode, you must first read the radio. Reading inputs the correct test freqs from the radio.

Setting the squelch is not trivial. You have two settings to adjust, open and tight. Open is set 3 dB below the receivers 12dB SINAD sensitivity and tight is set for 7dB above. If you don't have a calibrated signal generator and a SINAD meter to do this with, I would shy away from trying to fudge the settings. The x90 radios could loose their ability to unmute the speaker unless the monitor function is enabled. Don't know why this happens but suspect it has to do with with the RSSI settings which are also memorized with the squelch open/tight.

 

[car5le]

Thanks ramal121. My problem now appears is that I can't get the "Test Mode" button under Programming to become active. It just stays grayed out.

 

[ramal121]

Oops. Re-read your first post. You have a dual band set up. Yes the FPU will not allow you to enter test mode. I guess it just can't handle two radios at once. So now you have to jump through some hoops.

As an example, I'll assume VHF is radio one and UHF is radio two. Read the radio and save the archive.

Disconnect the UHF radio two control cable. Open a blank archive in FPU, change model to single head and single band VHF. Create a dummy channel. Insure there are some correct VHF test frequencies in its menu. Write this to the radio (ignore "model mismatch" message). You can now enter test mode and make adjustments to that radio.

Now it gets worse. You'll need to swap the KRK-7DB ends and put the one from radio one onto radio two.
Follow the above except program as a UHF single band single head. You can now tune the UHF.

Reassemble as original, program with your saved archive (again ignore "model mismatch") and you are good. A real PITA. Goes a little easier if you have it all out on a bench, but then you'll need a spare set of cables.

I have never done front panel tuning on a dual band X90. I don't know if you'll have to do the same kind of thing or what.

 

[car5le]

This is perfect! Thanks!

 

[w6hp]

Sorry to resurrect this very informative and old thread but I'm at a dead end.

I just want to clarify one step of the process.

As ramal121 suggested I’ve adjusted the squelch tight and open on Radio 1 (TK-790) and now need to adjust Radio 2 (TK-890)

Swapping the KRK-7DB end caps between Radio 1 and Radio 2 seems simple enough (not really) but will Radio 2 have power with the mods that were done making it Radio 2? R546 and R661 are gone and R602 was moved to R705.

I don’t want to go to the trouble of swapping the KRK-7’s only to find the 890 won’t power up with the mods done.

Will swapping the KRK-7's still give me power to the modded Radio 2?

Thanks.

 

[ramal121]

I believe the jumpers are for audio routing and won't affect the ability to power up and access radio 2.

Now if this knocks out the speaker to hear noise when adjusting the squelch I can't recall. If that is the case you'll have to just go by the green busy light for squelch open.

 

[w6hp]

It did indeed work and I was able to retune the squelch just fine.

Thanks.