Kenwood TK-840 (TKR-740) Repeater Experts??

[RFI-EMI-GUY]

Ok;
I have a new to me Kenwood TKR-840-1 which I plan to use on GMRS. So far I have reprogrammed it as I require. Very smooth programming.
As I received it it had been programmed near my frequency about 400 KHz higher. So I have not bothered to sweep the helicals. It seems it may be within the 5.0 MHz BW of the receiver.

My first question.
I have a carrier squelch pair in the radio (where it was previously programmed) and I wish to compare 12 dB SINAD points to my GMRS pairs which have multi tone table set. What I am finding is that the squelch is a bit tighter on the CSQ pair than where I am operating. SINAD seems close, it just wont break squelch until signal is somewhat higher

In the test mode found the analog and RSSI squelch settings in the tuner and adjusted them somewhat loose as I like it that way. However this CSQ channel seems to have some higher setting. Perhaps by design? Maybe I am missing something? Both are WB channels.

Yes I could just turn on a tone table and compare. But I want to learn something.

Second question.
The radio was set to about 3.5 W on high power. I went through the Test Mode tuning and adjusted for 5.0W high power using a known good bird wattmeter and HP8920B. I also calibrated the power meter to agree. I then attempted to set Low power to 1 watt and found that it reads on the test screen at about a fraction of a watt .1 to .2 W. When I calibrate the low power wattmeter, the high power channels read ridiculously high 27W. Is the power detector non linear??

The help screen for the power setting is written poorly and also I get a warning showing the TX ranges of the radio when I do a calibration. Not sure what that is about.

I have not opened the radio up so I am assuming all is set with soft pots.

Third question.

"Reverse Burst" seems the repeater receives it properly but when the repeater drops out, my SABER radios are not feeling the love. Looking at my HP8920B scope, the CTCSS tone is present throughout the drop out delay and there is no evidence of phase reversal or "chicken burst". Setting dropout delay to off accomplishes nothing. There are no reverse bursts heard during a conversation so squelch tail suppression by the decoder works. The radio just fails to eliminate squelch tail at the subscribers. Is this a "firmware thing"?

Lastly. How do I determine my firmware and HW version?

 

[a417]

"Reverse Burst" seems the repeater receives it properly but when the repeater drops out, my SABER radios are not feeling the love. Looking at my HP8920B scope, the CTCSS tone is present throughout the drop out delay and there is no evidence of phase reversal or "chicken burst". Setting dropout delay to off accomplishes nothing. There are no reverse bursts heard during a conversation so squelch tail suppression by the decoder works. The radio just fails to eliminate squelch tail at the subscribers. Is this a "firmware thing"?

there was many a-post over @ the batlabs about the "non-standard reverse burst" on Waris series models regarding this squelch crash using non-moto repeaters. Moto and Kenwood had different implementations (grossly paraphrasing) and they never really played well together. Given the vintage of the Saber line, this may be something you just need to deal with, although i'm sure the hive mind will have a suggestion.

 

[RFI-EMI-GUY]

there was many a-post over @ the batlabs about the "non-standard reverse burst" on Waris series models regarding this squelch crash using non-moto repeaters. Moto and Kenwood had different implementations (grossly paraphrasing) and they never really played well together. Given the vintage of the Saber line, this may be something you just need to deal with, although i'm sure the hive mind will have a suggestion.

It is not the SABER radios, it is the TKR-840 not applying any Squelch Tail Elimination when it de keys. I have looked with a scope. No phase reversal, no tone drop before the carrier drops. Nothing.

 

[a417]

Oh, I misunderstood...I need to read better. I'm sure you've already manipulated the STE timings to see if maybe there was a bad bit somewhere? Maybe forcing a new setting in there will help? When you reprogrammed it, did you read the codeplug from the unit and make the changes or did you build a new codeplug for the unit you recieved?

I've had more than enough units have subtly-bad codeplugs that still worked, and gave various BS issues that were resolved with a brand spankin' new codeplug...and then building it up from scratch.

 

[cmdrwill]

IS your Sabre set to And/OR squelch ?

 

[RFI-EMI-GUY]

IS your Sabre set to And/OR squelch ?

I don't think there is any option in the SABER. I think the default is "AND". Meaning that both noise squelch threshold and CTCSS tone decode must be true to unmute.

I think AND/OR may have been a default in Micor repeaters where CTCSS tone and noise squelch must be true initially, but CTCSS tone alone can maintain the repeater carrier. This allows weaker signals to be repeated with the two level squelch providing longer noise squelch hysteresis.

I have not seen a good write up on this subject so my recollection might be "noisy".

 

[RFI-EMI-GUY]

Oh, I misunderstood...I need to read better. I'm sure you've already manipulated the STE timings to see if maybe there was a bad bit somewhere? Maybe forcing a new setting in there will help? When you reprogrammed it, did you read the codeplug from the unit and make the changes or did you build a new codeplug for the unit you recieved?

I've had more than enough units have subtly-bad codeplugs that still worked, and gave various BS issues that were resolved with a brand spankin' new codeplug...and then building it up from scratch.

During an exchange between subscribers, the repeater receiver mutes just fine. It is the repeater TX on the drop out that crashes in a subscriber receiver.

When I look at the repeater drop out carrier on an oscilloscope, I see the CTCSS tone running until the repeater drops. No phase reversal seen or heard.


The only settings I find are in the Optional Features Tab as follows:

QT Reverse Burst Time (msec) Default = 160 (This I have adjusted to extremes)
Range: 140 to 200 msec (1 msec steps)

KENWOOD KPG-47D Help
During repeat with QT tones, the repeater re-transmits a phase-shifted burst of the QT tone ("reverse burst") when it detects the radio using the repeater has unkeyed and also sent its reverse QT burst (squelch-tail elimination). This mutes a receiving radio's speaker audio before its receiver circuit shuts off eliminating squelch tail noise in the speaker audio.

This function determines the time that the transmitter's carrier is allowed to remain on the air during and after the Reverse Burst itself. Typically this time should not have to be adjusted.

QT Decode Delay Time (msec) Default = 80
Range: Off (0) to 250 msec (1 msec steps)

KENWOOD KPG-47D Help
This function determines the time after detecting a QT reverse burst and being muted that the receiver delays beginning to decode new QT tones.

I reworked the original code plug as it was minimalistic. However it would not be hard to create a new one. Will I have to retune the radio if I use a fresh code plug?

 

[a417]

I reworked the original code plug as it was minimalistic. However it would not be hard to create a new one. Will I have to retune the radio if I use a fresh code plug?

We need to hear from the true Kenwood-whisperers on here, I'm just a half-breed. I can't tell you definitively on that one.

I would guess no, as you're not venturing down into ham bands from T band, you're staying in GMRS territory. Its well within its intended service footprint.

 

[mmckenna]

Not sure about the TKR-x40 software, but on some of the others there is an "engineering" serial number that opens up some options. I know on the KPG-89 there's settings for changing the reverse burst phase, +180º, +120º, -120º.

I don't have the software for those repeaters, so no clue if it's an option.

 

[RFI-EMI-GUY]

If I can only find the engineering SN I will give that a try.