The TKR-850/851 voltage regulator ¡°failures¡± are most often attributable to a design problem I tracked down a number of years ago after having two TKR-850¡¯s intermittently lose audio (of course, never while on the bench, only while at the sites).? Replacing the regulators, even with beefer ones, is not the cure.? This problem is on the control unit board B/2, and is related to one of the bus transceivers (IC606 if I remember right).? It is a design flaw that appears someone attempted to correct in later board revs but only made the problem worse.? ? Follow me here¡.might be helpful to open a service manual. ? There are three unused inputs on that problematic bus transceiver.? On most, if not all, versions of the board, those inputs are left floating - never a good idea.? As one of my EE professors used to say, ¡°floating inputs sink projects.¡±? The floating inputs can lead to oscillation. ? To make matters worse, Kenwood realized this was a problem but rather than tying the *inputs* high or low to hold them in a steady state, they left them floating but tied the *outputs* to ground on later versions of the board,. ?With the inputs in an indeterminate state, the oscillation can or will still occur, but now with the outputs shorted to ground, excessive current will be sourced by the bus transceiver to those grounded outputs, which in turn overloads the upstream voltage regulators, causing them to fold back due to over-temperature or over-current, thus killing audio through the DSP/codec. ? You¡¯ll have to look at your repeater¡¯s serial number, figure out which board rev it has, and compare it to the correct schematic to know for sure if this is what is causing your problem.? After having discovered these design flaws I¡¯ve fixed probably a dozen TKR¡¯s that had audio problems by modifying them so that the unused inputs were tied low and the outputs were left floating.? For good measure, I also replaced the previously-stressed Vregs upstream as well. ? Here¡¯s a list of all of the Vregs in a TKR in case you need to order any; most have easily-obtainable cross references to other manufacturers¡¯ parts. ? IC4 NJM7808FA ? IC5 AN8009M? SOT-89 TO-243AA ? IC10 TA7808F ? IC3, IC11 NJM78L05UA ? IC624 XC62FP1802P ? IC625, IC626 XC62FP3302P ? IC627, IC628, IC630 TA78L05F ? ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? --- Jeff WN3A ? ? ?
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From: [email protected] <[email protected]> On Behalf Of Jerry Dorf N0FWG
Sent: Sunday, April 27, 2025 10:31 AM
To: [email protected]
Subject: Re: [repeater-builder] TKR-850 No Receive? Something I posted back in 2018 on another board Plug a local mic in and see if it will key up and send audio / tone.. If it keys up with no audio then Check IC 628 on the front board for 5VDC, it supplies 2 other regulators IC 624 (1.8 V) and IC 625 (3.3 V). I have seen 2 of them with voltages less than 3.5V before Seems to be a common problem on ver 2.0 repeaters, some techs have wired a LM7805 in its place as the OEM part is marginal for the current demand. When this IC fails you will not have any receive or transmit audio, repeat audio. Keys will beep when pressed. It appears like the DSP chip is dead, due to lack of 2 critical voltages
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The Service Manual is on RB. The rear panel 15 pin Molex connector is for attaching an external (KES-4, etc) speaker. If the supplied jumpered male Molex is missing, the previous user had an external speaker. With the jumpered plug missing, the audio output path is open, there is no audio from the internal speaker. Either jumper the open connector or attach an external speaker. It is not software controlled. No jumpered plug, no front panel speaker output.
Pin 9 & 12 jumpered. See page 54 of the TKR-850 Service manual on the RB site.
Joel Berger W6BQD
Just in case you are not a vet with the 850, is there a molex plug in the connector under the transmit coax connector? On my Kenwoods it has to be there with 2 pins jumpered for the speaker to work.? Don¡¯t know if all configs need it but it took me a day to figure out that mine did. ? 73 Mike ? ? On 2025-04-26 11:50 p.m., Mike Sullivan via wrote: I have read it and programmed both a 70cm and a GMRS pair to test out. Both yield the same result, as stated above.
No audio at all. The antennas that the repeater and my base station are connected to are literally right next to each other, so there should be no problems at all.
Will be taking it to a friend to diagnose, just wanted to ask before I do so. ?
<-- What is the exact model of this 850, is it a version 1 or version 2 repeater? - reason for asking is that there was a design issue with earlier V1's (floating inputs on the DSP chip), which caused the 3.3V regulator (I think!) to fold, thus the audio amp having insufficient supply voltage. Despite this, you can also check for discriminator noise (with no RF signal applied) at pin 10 of the DB25, and once you inject a signal, you should see activity on this pin.? I would use a HT not a base station with antenna's so close! The other question is how far off from the original RX frequency are you? - the internal BPF has a 3dB BW of abut 10MHz:
 ? You will probably need to re-tune the RX (eventually), but for now, start with checking for noise and any sign of a signal on pin 10 of the rear DB25. ? <Credit to Jeff, WN3A for tutoring me on this stuff!>. ? Cheers, Ramesh, VA3UV, WA3UV ?
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Re: PD526 Duplexer Tuning
They came off other PD526¡¯s; how close the factory made them to 11.5¡±, and how accurately you can measure them after having been deformed by the tight bend radius on a 526, I can¡¯t say.? But I can promise you that even if they were off half an inch that it wouldn¡¯t result in that specific duplexer not meeting spec. ? ??????????????????????????????????????????????????????????????????????????????????????????????? --- Jeff ?WN3A ?
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From: [email protected] <[email protected]> On Behalf Of Part 15 Engineer via groups.io
Sent: Sunday, April 27, 2025 10:42 AM
To: [email protected]
Subject: Re: [repeater-builder] PD526 Duplexer Tuning? I measured the cable lengths and it's rg214 and it's approx 11.5 in for jumpers but they might be a hair over 11.5 inches. I'm not sure how critical the length is or how exact it must be. ? The first two plots are typical of each individual cavity. In this case the high side. The second two are with the two coupling loops in line on the 3 high side cavities minus the coupling tee. So I'm guessing like you guys stated earlier it's the coupling cables? I didn't tune the cavities anymore. Just tuned them individually and installed the cables and this is from input to output with two coupling loops installed. Does anyone have a good set of harness cables? I bought these from an individual on here but apparently they are not the right cables? ? A number of things: ? - You¡¯re sweeping 30 MHz wide with only 401 points.? You need to either narrow down your sweep just to the range of interest, use more points, or more likely a combination of both.? I¡¯d typically be using a 10 MHz span and 1601 points (I don¡¯t have a NanoVNA, I don¡¯t know what it¡¯s capabilities are).
- Something is either very wrong with the cavity, or the calibration.? It is showing you have 3.129 of insertion loss in the bandpass; it should be about 0.25 dB for a properly-functioning PD526 resonator.? Likewise, at the notch frequency, it¡¯s showing that you have 4.77 dB of return loss ¨C it should be a lot closer to zero.? If I were to take a WAG, you have 3 dB or more of cable loss that isn¡¯t compensated for, and/or something is wrong with your calibration kit.
- No since in working on the full duplexer harnessed together until the above are first addressed and you know each cavity is properly tuned individually.
? --- Jeff WN3A ? ? Here is the plot for a single cavity. ? Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like? ? I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet. ? It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL . On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd=[email protected]> wrote: Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches? ? Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
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Re: PD526 Duplexer Tuning
It's only capable of 1024 points max. I think everything else I can set to your specs.
On Sun, Apr 27, 2025, 8:41?AM Part 15 Engineer < kc8gpd@...> wrote: I measured the cable lengths and it's rg214 and it's approx 11.5 in for jumpers but they might be a hair over 11.5 inches. I'm not sure how critical the length is or how exact it must be.
The first two plots are typical of each individual cavity. In this case the high side. The second two are with the two coupling loops in line on the 3 high side cavities minus the coupling tee. So I'm guessing like you guys stated earlier it's the coupling cables? I didn't tune the cavities anymore. Just tuned them individually and installed the cables and this is from input to output with two coupling loops installed. Does anyone have a good set of harness cables? I bought these from an individual on here but apparently they are not the right cables?
Thanks
Robert
A number of things: ? - You¡¯re sweeping 30 MHz wide with only 401 points.? You need to either narrow down your sweep just to the range of interest, use more points, or more likely a combination of both.? I¡¯d typically be using a 10 MHz span and 1601 points (I don¡¯t have a NanoVNA, I don¡¯t know what it¡¯s capabilities are).
- Something is either very wrong with the cavity, or the calibration.? It is showing you have 3.129 of insertion loss in the bandpass; it should be about 0.25 dB for a properly-functioning PD526 resonator.? Likewise, at the notch frequency, it¡¯s showing that you have 4.77 dB of return loss ¨C it should be a lot closer to zero.? If I were to take a WAG, you have 3 dB or more of cable loss that isn¡¯t compensated for, and/or something is wrong with your calibration kit.
- No since in working on the full duplexer harnessed together until the above are first addressed and you know each cavity is properly tuned individually.
? --- Jeff WN3A ? ? Here is the plot for a single cavity. ? Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like? Thanks
![]() ? I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet. ? It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL . On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd=[email protected]> wrote: Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches? ? Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
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Re: PD526 Duplexer Tuning
I measured the cable lengths and it's rg214 and it's approx 11.5 in for jumpers but they might be a hair over 11.5 inches. I'm not sure how critical the length is or how exact it must be.
The first two plots are typical of each individual cavity. In this case the high side. The second two are with the two coupling loops in line on the 3 high side cavities minus the coupling tee. So I'm guessing like you guys stated earlier it's the coupling cables? I didn't tune the cavities anymore. Just tuned them individually and installed the cables and this is from input to output with two coupling loops installed. Does anyone have a good set of harness cables? I bought these from an individual on here but apparently they are not the right cables?
Thanks
Robert
A number of things: ? - You¡¯re sweeping 30 MHz wide with only 401 points.? You need to either narrow down your sweep just to the range of interest, use more points, or more likely a combination of both.? I¡¯d typically be using a 10 MHz span and 1601 points (I don¡¯t have a NanoVNA, I don¡¯t know what it¡¯s capabilities are).
- Something is either very wrong with the cavity, or the calibration.? It is showing you have 3.129 of insertion loss in the bandpass; it should be about 0.25 dB for a properly-functioning PD526 resonator.? Likewise, at the notch frequency, it¡¯s showing that you have 4.77 dB of return loss ¨C it should be a lot closer to zero.? If I were to take a WAG, you have 3 dB or more of cable loss that isn¡¯t compensated for, and/or something is wrong with your calibration kit.
- No since in working on the full duplexer harnessed together until the above are first addressed and you know each cavity is properly tuned individually.
? --- Jeff WN3A ? ? Here is the plot for a single cavity. ? Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like? Thanks
![]() ? I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet. ? It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL . On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd=[email protected]> wrote: Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches? ? Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
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Re: PD526 Duplexer Tuning
You got the cables from me, and they are decidedly the correct cables.? The four 11.5¡± cables go between cavities, the 12¡± cables go to the triple-female tee that I sent. ? It has to be something wrong with either the test equipment, testcables/cal kit, or methodology.? Or you have one or more bad resonators in the duplexer itself. ? In your prior post you said to ¡°ignore the first two plots¡±, but I only see two plots in the email that preceded that, so I don¡¯t know what I should be looking at. ? In your-most recent email, if there were any plots attached, they didn¡¯t come through ¨C there is a box with an X that says ¡°The linked image cannot be displayed.? The file may have been moved, renamed, or deleted.? Verify that the link points to the correct file location.¡±? Don¡¯t send links, don¡¯t embed images HTML, send the sweep images as attachments. ? Let¡¯s go back to step 1.? ? - ?Set up the VNA correctly (again, I don¡¯t have a NanoVNA, so you¡¯ll have to figure out how to do this):
- 10 MHz span centered roughly mid-way between your Tx and Rx frequencies at some whole-MHz value
- 1601 data points
- A reasonably low bandwidth (10 kHz or less)
- No averaging, no smoothing
- Do a full 2-port calibration using your test cables and cal kit OSL, no adapters
- At the end of cabliration, send a sweep of what your VNA shows with the test cables connected to each other with the thru adapter (presumably an N-female ¡°barrel¡±)
- Tune one of the high-pass cavities:
- Tune the pass for best return loss (S11), ignore insertion loss (S21).
- Tune the notch (S21).? The pass shouldn¡¯t have moved if the notch was close to being correct already, but if it did move a bit, repeat a) and b).
- Send the sweep
- Tune one of the low-pass cavities per #2 above and send the sweep.
- Tune the remaining four cavities individually, and confirm that each one¡¯s sweep looks virtually identical to the sweeps from #2 and #3.? A single cavity should have right around 30 dB return loss and 0.25 dB insertion loss for the pass (and again, you tune the pass for maximum return loss, not least insertion loss although the two will be close).? The notch should be 40 dB +/- 2 dB at a 5 MHz split.? If any resonator doesn¡¯t meet those specs then it has a problem that needs to be addressed.
- Don¡¯t bother harnessing it up until we successfully get through the above.
? --- Jeff WN3A ?
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Something I posted back in 2018 on another board
?
Plug a local mic in and see if it will key up and send audio / tone.. If it keys up with no audio then
Check IC 628 on the front board for 5VDC, it supplies 2 other regulators IC 624 (1.8 V) and IC 625 (3.3 V).
?
I have seen 2 of them with voltages less than 3.5V before
?
Seems to be a common problem on ver 2.0 repeaters, some techs have wired a LM7805 in its place as the OEM part is marginal for the current demand.
?
When this IC fails you will not have any receive or transmit audio, repeat audio. Keys will beep when pressed.
It appears like the DSP chip is dead, due to lack of 2 critical voltages
?
Jerry
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OK Mike, I see you already had replies about the audio jumper on the big molex connector.? It has been a couple of years since I had to program one but make sure you exit program mode before you test, I seem to recall the repeater does not function as expected while you are in program / setup mode.? Again, I am doing this from memory and I carry a photo ID so I can remember who I am sometimes.? They are pretty good repeaters so best of luck. ? Mike ?
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From: [email protected] <[email protected]> On Behalf Of mike@...
Sent: Sunday, April 27, 2025 10:15 AM
To: [email protected]
Subject: Re: [repeater-builder] TKR-850 No Receive? Just in case you are not a vet with the 850, is there a molex plug in the connector under the transmit coax connector? On my Kenwoods it has to be there with 2 pins jumpered for the speaker to work.? Don¡¯t know if all configs need it but it took me a day to figure out that mine did. ? 73 Mike ? ? On 2025-04-26 11:50 p.m., Mike Sullivan via groups.io wrote: I have read it and programmed both a 70cm and a GMRS pair to test out. Both yield the same result, as stated above.
No audio at all. The antennas that the repeater and my base station are connected to are literally right next to each other, so there should be no problems at all.
Will be taking it to a friend to diagnose, just wanted to ask before I do so. ?
<-- What is the exact model of this 850, is it a version 1 or version 2 repeater? - reason for asking is that there was a design issue with earlier V1's (floating inputs on the DSP chip), which caused the 3.3V regulator (I think!) to fold, thus the audio amp having insufficient supply voltage. Despite this, you can also check for discriminator noise (with no RF signal applied) at pin 10 of the DB25, and once you inject a signal, you should see activity on this pin.? I would use a HT not a base station with antenna's so close! The other question is how far off from the original RX frequency are you? - the internal BPF has a 3dB BW of abut 10MHz:
 ? You will probably need to re-tune the RX (eventually), but for now, start with checking for noise and any sign of a signal on pin 10 of the rear DB25. ? <Credit to Jeff, WN3A for tutoring me on this stuff!>. ? Cheers, Ramesh, VA3UV, WA3UV ?
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Just in case you are not a vet with the 850, is there a molex plug in the connector under the transmit coax connector? On my Kenwoods it has to be there with 2 pins jumpered for the speaker to work.? Don¡¯t know if all configs need it but it took me a day to figure out that mine did. ? 73 Mike ?
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From: [email protected] <[email protected]> On Behalf Of Ramesh Dhami \(VA3UV\)
Sent: Sunday, April 27, 2025 9:31 AM
To: [email protected]
Subject: Re: [repeater-builder] TKR-850 No Receive? On 2025-04-26 11:50 p.m., Mike Sullivan via groups.io wrote: I have read it and programmed both a 70cm and a GMRS pair to test out. Both yield the same result, as stated above.
No audio at all. The antennas that the repeater and my base station are connected to are literally right next to each other, so there should be no problems at all.
Will be taking it to a friend to diagnose, just wanted to ask before I do so. ?
<-- What is the exact model of this 850, is it a version 1 or version 2 repeater? - reason for asking is that there was a design issue with earlier V1's (floating inputs on the DSP chip), which caused the 3.3V regulator (I think!) to fold, thus the audio amp having insufficient supply voltage. Despite this, you can also check for discriminator noise (with no RF signal applied) at pin 10 of the DB25, and once you inject a signal, you should see activity on this pin.? I would use a HT not a base station with antenna's so close! The other question is how far off from the original RX frequency are you? - the internal BPF has a 3dB BW of abut 10MHz:
 ? You will probably need to re-tune the RX (eventually), but for now, start with checking for noise and any sign of a signal on pin 10 of the rear DB25. ? <Credit to Jeff, WN3A for tutoring me on this stuff!>. ? Cheers, Ramesh, VA3UV, WA3UV ?
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Re: PD526 Duplexer Tuning
The first two plots are typical of each individual cavity. In this case the high side. The second two are with the two coupling loops in line on the 3 high side cavities minus the coupling tee. So I'm guessing like you guys stated earlier it's the coupling cables? I didn't tune the cavities anymore. Just tuned them individually and installed the cables and this is from input to output with two coupling loops installed. Does anyone have a good set of harness cables? I bought these from an individual on here but apparently they are not the right cables?
Thanks
Robert
A number of things: ? - You¡¯re sweeping 30 MHz wide with only 401 points.? You need to either narrow down your sweep just to the range of interest, use more points, or more likely a combination of both.? I¡¯d typically be using a 10 MHz span and 1601 points (I don¡¯t have a NanoVNA, I don¡¯t know what it¡¯s capabilities are).
- Something is either very wrong with the cavity, or the calibration.? It is showing you have 3.129 of insertion loss in the bandpass; it should be about 0.25 dB for a properly-functioning PD526 resonator.? Likewise, at the notch frequency, it¡¯s showing that you have 4.77 dB of return loss ¨C it should be a lot closer to zero.? If I were to take a WAG, you have 3 dB or more of cable loss that isn¡¯t compensated for, and/or something is wrong with your calibration kit.
- No since in working on the full duplexer harnessed together until the above are first addressed and you know each cavity is properly tuned individually.
? --- Jeff WN3A ? ? Here is the plot for a single cavity. ? Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like? Thanks
 ? I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet. ? It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL . On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd=[email protected]> wrote: Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches? ? Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
|
On 2025-04-26 11:50 p.m., Mike Sullivan
via groups.io wrote:
I have read it and programmed both a 70cm and a GMRS pair
to test out. Both yield the same result, as stated above.
No audio at all. The antennas that the repeater and my base
station are connected to are literally right next to each
other, so there should be no problems at all.
Will be taking it to a friend to diagnose, just wanted to ask
before I do so.
<-- What is the exact model of this 850, is it a version 1 or
version 2 repeater? - reason for asking is that there was a design
issue with earlier V1's (floating inputs on the DSP chip), which
caused the 3.3V regulator (I think!) to fold, thus the audio amp
having insufficient supply voltage.
Despite this, you can also check for discriminator noise (with no
RF signal applied) at pin 10 of the DB25, and once you inject a
signal, you should see activity on this pin.? I would use a HT not
a base station with antenna's so close!
The other question is how far off from the original RX frequency
are you? - the internal BPF has a 3dB BW of abut 10MHz:
You will probably need to re-tune the RX (eventually), but for
now, start with checking for noise and any sign of a signal on pin
10 of the rear DB25.
<Credit to Jeff, WN3A for tutoring me on this stuff!>.
Cheers,
Ramesh, VA3UV, WA3UV
|
Re: Help with out of range programming a Motorola GP300
Oops, yes typo.? Should have been 433...
?
I'm trying to get them programmed to local Amateur repeartes in the 441 to 444 MHz receive range with 446-449 matching 5 MHz offset TX.
?
ron
KA3JIJ
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"The antennas that the repeater and my base station are connected to are literally right next to each other, so there should be no problems at all."
That may have been the problem. May have blown the front end of the receiver.
Mick - W7CAT
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----- Original Message ----- From: "Mike Sullivan via groups.io" To: [email protected]Sent: Saturday, April 26, 2025 09:50:41 PM Subject: Re: [repeater-builder] TKR-850 No Receive On Sat, Apr 26, 2025 at 11:38 PM, Ramesh Dhami \(VA3UV\) wrote:
On 2025-04-26 11:33 p.m., Mike Sullivan via groups.io wrote:
Got a TKR-850 that was abandoned at a tower site.. powers on and
transmits fine (can transmit using CW ID button and getting 25w
output) but receive appears deaf, Busy light is staying on and can't
key it up with any amount of power. Tried both ham and GMRS
frequencies, both exhibit the same behavior. Checked all the usual
settings and can't get it to go away. Any ideas of anything else to
check before I say she's dead and just plan on using a mobile for
receive?
<-- Hi Mike:? Have you been able to "read" the repeater using the
Kenwood programming software (i.e., to confirm he RX frequency)?
Can you hear anything via the local speaker (you do need the loop-back
connector plugged into the 15 pin molex connector / or you can
carefully use a jumper wire to enable the front speaker.
Do you have any test equipment (signal generator, RF test set, etc.)?
Ramesh, VA3UV, WA3UV I have read it and programmed both a 70cm and a GMRS pair to test
out. Both yield the same result, as stated above.
No audio at all. The antennas that the repeater and my base station
are connected to are literally right next to each other, so there should be no problems at all.
Will be taking it to a friend to diagnose, just wanted to ask before
I do so.
On Sat, Apr 26, 2025 at 11:41 PM, Jeremy Hansen wrote:
Are you saying the busy light stays on regardless of whether you're
transmitting a test signal? (i.e. all of the time?)
If so, is there any audio being generated at the local speaker???
Have you programmed a function button to open the Squelch, and if so are you
hearing RX noise when activated?
Jeremy K1LFK
On Sat, Apr 26, 2025, 10:33?PM Mike Sullivan via groups.io (
) wrote:
Got a TKR-850 that was abandoned at a tower site.. powers on and
transmits fine (can transmit using CW ID button and getting 25w output) but
receive appears deaf, Busy light is staying on and can't key it up with
any amount of power. Tried both ham and GMRS frequencies, both exhibit the same
behavior. Checked all the usual settings and can't get it to go
away. Any ideas of anything else to check before I say she's dead and just
plan on using a mobile for receive?
Mike
Correct, comes on when the repeater goes on and stays on. No audio
generated. I have done so, and don't hear anything. I did find some older topics regarding a FM IC going bad, which is common on these. Probably what's going on here.
Just checking all settings and making sure I'm not missing something
stupid before diagnosing as a bad IC.
Mike
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On Sat, Apr 26, 2025 at 11:38 PM, Ramesh Dhami \(VA3UV\) wrote:
On 2025-04-26 11:33 p.m., Mike Sullivan via groups.io wrote:
Got a TKR-850 that was abandoned at a tower site.. powers on and
transmits fine (can transmit using CW ID button and getting 25w
output) but receive appears deaf, Busy light is staying on and can't
key it up with any amount of power. Tried both ham and GMRS
frequencies, both exhibit the same behavior. Checked all the usual
settings and can't get it to go away. Any ideas of anything else to
check before I say she's dead and just plan on using a mobile for receive?
<-- Hi Mike:? Have you been able to "read" the repeater using the
Kenwood programming software (i.e., to confirm he RX frequency)?
Can you hear anything via the local speaker (you do need the loop-back
connector plugged into the 15 pin molex connector / or you can carefully
use a jumper wire to enable the front speaker.
Do you have any test equipment (signal generator, RF test set, etc.)?
Ramesh, VA3UV, WA3UV
I have read it and programmed both a 70cm and a GMRS pair to test out. Both yield the same result, as stated above. No audio at all. The antennas that the repeater and my base station are connected to are literally right next to each other, so there should be no problems at all. Will be taking it to a friend to diagnose, just wanted to ask before I do so.
On Sat, Apr 26, 2025 at 11:41 PM, Jeremy Hansen wrote:
Are you saying the busy light stays on regardless of whether you're transmitting a test signal? (i.e. all of the time?)
If so, is there any audio being generated at the local speaker??? Have you programmed a function button to open the Squelch, and if so are you hearing RX noise when activated?
Jeremy K1LFK
Got a TKR-850 that was abandoned at a tower site.. powers on and transmits fine (can transmit using CW ID button and getting 25w output) but receive appears deaf, Busy light is staying on and can't key it up with any amount of power. Tried both ham and GMRS frequencies, both exhibit the same behavior. Checked all the usual settings and can't get it to go away. Any ideas of anything else to check before I say she's dead and just plan on using a mobile for receive?
Mike
Correct, comes on when the repeater goes on and stays on. No audio generated. I have done so, and don't hear anything. I did find some older topics regarding a FM IC going bad, which is common on these. Probably what's going on here. Just checking all settings and making sure I'm not missing something stupid before diagnosing as a bad IC. Mike
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Are you saying the busy light stays on regardless of whether you're transmitting a test signal? (i.e. all of the time?)
If so, is there any audio being generated at the local speaker??? Have you programmed a function button to open the Squelch, and if so are you hearing RX noise when activated?
Jeremy K1LFK
Got a TKR-850 that was abandoned at a tower site.. powers on and transmits fine (can transmit using CW ID button and getting 25w output) but receive appears deaf, Busy light is staying on and can't key it up with any amount of power. Tried both ham and GMRS frequencies, both exhibit the same behavior. Checked all the usual settings and can't get it to go away. Any ideas of anything else to check before I say she's dead and just plan on using a mobile for receive?
Mike
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On 2025-04-26 11:33 p.m., Mike Sullivan via groups.io wrote: Got a TKR-850 that was abandoned at a tower site.. powers on and transmits fine (can transmit using CW ID button and getting 25w output) but receive appears deaf, Busy light is staying on and can't key it up with any amount of power. Tried both ham and GMRS frequencies, both exhibit the same behavior. Checked all the usual settings and can't get it to go away. Any ideas of anything else to check before I say she's dead and just plan on using a mobile for receive? <-- Hi Mike:? Have you been able to "read" the repeater using the Kenwood programming software (i.e., to confirm he RX frequency)? Can you hear anything via the local speaker (you do need the loop-back connector plugged into the 15 pin molex connector / or you can carefully use a jumper wire to enable the front speaker. Do you have any test equipment (signal generator, RF test set, etc.)? Ramesh, VA3UV, WA3UV
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Got a TKR-850 that was abandoned at a tower site.. powers on and transmits fine (can transmit using CW ID button and getting 25w output) but receive appears deaf, Busy light is staying on and can't key it up with any amount of power. Tried both ham and GMRS frequencies, both exhibit the same behavior. Checked all the usual settings and can't get it to go away. Any ideas of anything else to check before I say she's dead and just plan on using a mobile for receive?
Mike
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Telewave makes a folded dipole that works very well.? I regularly drive by a
California Highway Patrol office that has two on the tower.?
Here's the 45-54 MHz model:?
?
I've ordered Telewave through Talley.? They give an amateur discount (at least
the local office does), they would probably give it to Red Cross.
Not knowing your situation, your director may get sticker shock with the price of
a new commercial Sinclair or Telewave antenna even with a discount.?
If a homebrew creation would be acceptable, then you might want to look at this:
?
Or this:? (it's VHF-UHF but I'll bet it can be scaled, you might want to contact the author, his email address is at the end of the article)?
?
Mike WA6ILQ
?
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I know this is a long shot, but does anyone have a pair of channel elements crystalled for 147.180 TX, 147.780 RX for the MSR-2000 they'd like to sell? I thought I'd check here before I order a set from Klove. Thanks in advance.
?
Terry KM5UQ
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Re: Astron RM-50M conversion
A Victron Smart with a Victron SmartShunt right at the battery (such that the shunt only sees battery current and not load current) is a reasonable approach if you have lead-acid (flooded or AGM). See this note in the manual for why: In order to end the absorption phase at the correct point, it is important that the true current flow into the battery is referenced in relation to the tail current threshold, rather than the charger output current which may be significantly higher; if any loads are powered while charging a portion of the charger output current will be flowing directly to the loads, making the tail current condition more difficult or impossible to meet without current sense.
On Sat, Apr 26, 2025 at 3:21?PM Jim Aspinwall via <jim.no1pc= [email protected]> wrote:
Since I'm not stuck on the Iota, a Victron Smart IP22, IP43, IP67 12/30 or 12/50 - are spec'd to 14.7v max.
Quick review of battery products...
LiTime - max V = 14.6
BattleBorn = 14.7
WattCycle = 14.8
Bioenno = 14.6
There doesn't seem to be a cleaner/smarter way to do this other than ye olde Charger -> Batteries -> Load(s) if the goal is to have no power interruption when AC mains drops/burps.??
Then consider what's alive, presenting a load, in the rack, for how long.? A certain popular/familiar radio draws ~10A at 50W output.? Another popular piece of gear for linking... CDM-1250, ~8A @ 20-25w.? Controller bits, AllStar node, networking... another 5A perhaps.? 25A... for what run cycle?? Our longest on-air time is an intermittent 15-20 minutes of weekly net check-in, then continuous playout of AR Newsline.??
Ought to be able to cover that with 2x 100AH batteries and charger, and recover reasonably soon.? That's essentially what I've got at home, plus 400w of solar, running for the past 6-8 months.? The whole shack - HF, VHF/UHF rigs, and local repeater seem to be doing pretty well and is 'idling' at 14.38 v - can't find my ammeter to re-check the idle vs active draws.
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terry dalpoas