Hello,
I'm having FM trouble with a Kenwood KT-8300. I'm fare from an expert when it comes to fm so I could use some input. This particular tuner was brought to me a first time in fully original condition with power supply issues and noisy transistors. I replaced all the caps and faulty transistors and cleaned the commands. It had been working perfectly at its owner place until he decided to replace the 75ohm connecter to a BNC type which he added in parallel. His sight is not that good nor are his soldering skills so he made a mess and finally decided to ship it back to me indicating that he could no longer dial in to any station. After cleaning up hiss mess and reconnecting everything it would tune to some very strong stations but with a lot of noise and no stereo, the signal strength meter does not move at all. I guessed maybe adding a second coax connector in parallel wasn't doing wonders with the impedance matching so I decided to disconnect one of them going back to original but with very similar results. He assures me he did not touche any of the adjustments inside. I connected a fm signal generator straight to the BNC antenna input and got about 3 out of 5 on the signal strength meter with the output at its highest.
I'm having FM trouble with a Kenwood KT-8300. I'm fare from an expert when it comes to fm so I could use some input. This particular tuner was brought to me a first time in fully original condition with power supply issues and noisy transistors. I replaced all the caps and faulty transistors and cleaned the commands. It had been working perfectly at its owner place until he decided to replace the 75ohm connecter to a BNC type which he added in parallel. His sight is not that good nor are his soldering skills so he made a mess and finally decided to ship it back to me indicating that he could no longer dial in to any station. After cleaning up hiss mess and reconnecting everything it would tune to some very strong stations but with a lot of noise and no stereo, the signal strength meter does not move at all. I guessed maybe adding a second coax connector in parallel wasn't doing wonders with the impedance matching so I decided to disconnect one of them going back to original but with very similar results. He assures me he did not touche any of the adjustments inside. I connected a fm signal generator straight to the BNC antenna input and got about 3 out of 5 on the signal strength meter with the output at its highest.
The KT8300 is one of the best tuners I've owned. It is superselective and very good sounding, two attributes that don't always match. Have you cleaned the ganged tuner assembly? Compressed air at a not too deadly force will do the job. It may be the tuner needs a full realignment. At it's age, it wouldn't do any harm. As I type this, you might want to check both the ground and signal path from the antenna input to the pcb. Also, check for any cold solder joints on the pcb, especially on the antenna path. I miss that tuner, but all my local stations have gone to MP3 playback and digital broadcasting so tuner quality in my area is no longer a factor.
Hi Depaj,
I service a lot of tuners, and align them.
From what you are saying, something else has happened. He didn't stop at adding a connector. I think you are looking at what we call "panicking technician syndrome". That's where the repair goes off the rails and they do things in other places that would not make sense. Time to get the full truth out of your customer. Don't just do anything to find the issue, talk to him before anything. Tell him the smallest thing can save him a lot of money.
The first thing people do is turn adjustments. They'll try to turn them back later and think they have them in their original positions. Nope. They can also break cores or trimmer capacitors.
It is possible he overheated the cable and shorted the co-ax to the tuner.
I service a lot of tuners, and align them.
From what you are saying, something else has happened. He didn't stop at adding a connector. I think you are looking at what we call "panicking technician syndrome". That's where the repair goes off the rails and they do things in other places that would not make sense. Time to get the full truth out of your customer. Don't just do anything to find the issue, talk to him before anything. Tell him the smallest thing can save him a lot of money.
The first thing people do is turn adjustments. They'll try to turn them back later and think they have them in their original positions. Nope. They can also break cores or trimmer capacitors.
It is possible he overheated the cable and shorted the co-ax to the tuner.
Love Anatech's reply. He may be close to the truth, especially if the original tech's soldering was the mess you describe. It might be something very simple. I would also suggest a good alignment afterward if you want the the best performance. I had a customer who was a looney-tune FM freak in the 80s and 90s. I got to hear both a Marantz 10B and a Mac MR78 before and after alignments. There was no comparison in the performance. I don't remember who did the alignment on the 10B but Modafferi did the MR78. Two incredible tuners. The 10B was better from a sheer sound quality basis, but the MR78 brought in more stations with minimal noise. I miss the days of quality local FM broadcasts. WAMC in Albany, New York, used to broadcast concert from the Troy Music Hall in Albany, and they were serious audiophile quality broadcasts. I'm afraid those days are gone for now.
I got a KT9900 running.... clone of the KT8300.
I'm curious what you find. Mine was very well maintained by the seller who is a tuner specialist and collector in San Diego. It was calibrated before I got it.
It works really well even with an indoor Terk antenna. Catching the stations from Mt. Wilson up North. Please let us know what you find.
I'm curious what you find. Mine was very well maintained by the seller who is a tuner specialist and collector in San Diego. It was calibrated before I got it.
It works really well even with an indoor Terk antenna. Catching the stations from Mt. Wilson up North. Please let us know what you find.
Hello all and thank you for your inputs.
It was not a technician who touched the tuner but the owner who knows nothing about electronics and assured me he was incapable of even trying to adjust anything as he does not have the slightest clue how to do that. He just wanted to add a connector that better suited his installation. I am far from a tuner expert and am not well equipped to do detailed alignment procedures. My fm signal generator is very basic and old so probably not well aligned itself.
I did check the first RF stage and could not improve results with the alignement so I stopped assuming something had to be wrong at this point. I verified that the coax cable wasn't shorted and checked for continuity all the way to the board. The coax cable has been soldered and desoldered multiple times so that was the first thing I checked. I even tried connecting a coax antenna directly to the input pins on the board but without improvement.
It was not a technician who touched the tuner but the owner who knows nothing about electronics and assured me he was incapable of even trying to adjust anything as he does not have the slightest clue how to do that. He just wanted to add a connector that better suited his installation. I am far from a tuner expert and am not well equipped to do detailed alignment procedures. My fm signal generator is very basic and old so probably not well aligned itself.
I did check the first RF stage and could not improve results with the alignement so I stopped assuming something had to be wrong at this point. I verified that the coax cable wasn't shorted and checked for continuity all the way to the board. The coax cable has been soldered and desoldered multiple times so that was the first thing I checked. I even tried connecting a coax antenna directly to the input pins on the board but without improvement.
Hi Depaj,
Okay. Well, you know something changed and it wasn't just the cable / connector.
Customers will say something like what you were told. At times they are embarrassed and don't understand that if you have to hunt for the fault it will cost them more than if they were just up front and honest. People will try anything, like a "simple" adjustment.
One thing you can try is connect your oscilloscope past the first IF amplifier. It will have been amplified and you should be able to see level changes. The S meter is a good indicator if you have enough signal. You don't want to pound a signal in there. Just apply a strong signal. Being 10.7 MHz, most oscilloscopes will have a usable display.
I have probably 7 RF generators I can use, a couple stereo units. Typically I'll use three mixed into my own little radio universe instead of relying on broadcast stations. It just makes it easier with known levels. Tracking is normally done around 92 MHz and 106 MHz, I have a dead spot at 101.1 MHz, so I use that for fine tuning of the detector and IFT. You'll just be adjusting a single RF generator a lot as tracking and sensitivity are interactive adjustments between high and low on the band. You can deviate slightly from the instructions. A THD meter is pretty much required for the detector.
Don't get discouraged. I once got a Revox B261 tuner in, struck by a know-it-all "technician". Between installing the correct parts and alignment, it took two entire days to get it bang-on again. The replaced parts were not necessary, I was provided with the original parts and back in they went. Granted, alignment on these is much more involved than normal. Kenwood tuners can have convoluted instructions as well (not my favorite to align).
If you don't feel like diving into this, refer him to a good tuner tech. Don't get dragged between them.
Okay. Well, you know something changed and it wasn't just the cable / connector.
Customers will say something like what you were told. At times they are embarrassed and don't understand that if you have to hunt for the fault it will cost them more than if they were just up front and honest. People will try anything, like a "simple" adjustment.
One thing you can try is connect your oscilloscope past the first IF amplifier. It will have been amplified and you should be able to see level changes. The S meter is a good indicator if you have enough signal. You don't want to pound a signal in there. Just apply a strong signal. Being 10.7 MHz, most oscilloscopes will have a usable display.
I have probably 7 RF generators I can use, a couple stereo units. Typically I'll use three mixed into my own little radio universe instead of relying on broadcast stations. It just makes it easier with known levels. Tracking is normally done around 92 MHz and 106 MHz, I have a dead spot at 101.1 MHz, so I use that for fine tuning of the detector and IFT. You'll just be adjusting a single RF generator a lot as tracking and sensitivity are interactive adjustments between high and low on the band. You can deviate slightly from the instructions. A THD meter is pretty much required for the detector.
Don't get discouraged. I once got a Revox B261 tuner in, struck by a know-it-all "technician". Between installing the correct parts and alignment, it took two entire days to get it bang-on again. The replaced parts were not necessary, I was provided with the original parts and back in they went. Granted, alignment on these is much more involved than normal. Kenwood tuners can have convoluted instructions as well (not my favorite to align).
If you don't feel like diving into this, refer him to a good tuner tech. Don't get dragged between them.