I have on many occasions with different tuners, radios, or receivers tuned in a station on one, and had the the station tuned in on the other tuner blank out.

It happens when one is tuned to the left of the dial and one to the right.

They have to be pretty close to each other.

It is weird, but I am sure someone could explain it.

Your thoughts?

Rob

Probably the local oscillator in one tuner throwing out a signal which the other tuner is picking up. I presume the two tuners in question are in fairly close proximity to one another.

Why run two tuners at the same time?

I have on many occasions with different tuners, radios, or receivers tuned in a station on one, and had the the station tuned in on the other tuner blank out.

It happens when one is tuned to the left of the dial and one to the right.

They have to be pretty close to each other.

It is weird, but I am sure someone could explain it.

Your thoughts?

Rob

That happens to me as well. I have been meaning to ask that question for awhile now. Sometimes one or more just produce no sound until I shut another off.

Why run two tuners at the same time?

Why not ???????

Isn't this the fundamental principal of the heterodyne receiver?

Why run two tuners at the same time?



Why not ???????

What is the benefit?

Stereo!

What is the benefit?

How else are you gonna do an A/B test to hear which tuner is better?

Yes, I've noticed the effect but no, I don't know what causes it.

Why run two tuners at the same time?

I use three simultaneously.

Kinda like having pre-sets.:D

If you get one that is "slower" than another, and play them both simultaneously, you can get delayed "reverb" surround effects! :music: :D

If you get one that is "slower" than another, and play them both simultaneously, you can get delayed "reverb" surround effects! :music: :D

Cool!!!:thmbsp:

I use three simultaneously.

Kinda like having pre-sets.:D

you beat me to it , but i think you need a few more.

you beat me to it , but i think you need a few more.

I would, Chris, I would, if only I had more free:scratch2: inputs...

Stereo!

No, quad!

What is the benefit?

Not really a benefit, really fanaticism running many integrateds, tuners and loudspeakers together. I have about 15 complete 'systems' in my home office with tons of tuners. Helps with the boredom of the job. Additionally, I do a lot of A/B comparisons, and DX'ing contests between them. It gets crowded.

Vito

I have noticed the same effect when comparing tuners. The worst offender is my CT-1010. When I tune it while listening to another tuner some pretty nasty noises came out of the speakers. I thought it was doing something through the pre-amp, had not considered it could be RF related. Makes sense.

Right now I have 4 hooked up to one sytem. The CT-1010 and KT-8007 each sound fantastic but different, while the Proton 440 is the go to tuner when the other two are too noisy. The Luxman T-4 is hooked up because it looks so cool and is so fun to use with the Accutouch system that magnetically locks the dial when you are optimally tuned.

I need about 4 more inputs for the others....

Sounds like censorship for sure. Damn that big brother.

dew.

Never had this problem, and I thought I had them all!

Why run two tuners at the same time?

relatively cheap Quad? :D

Why run two tuners at the same time?Upstairs and downstairs. :yes:

I've had the same experience occasionally.

I've experienced this, too. The only thing I can liken it to is having two woofers wired out of phase. They are each producing sound waves, but those waves cancel each other out. With tuners it happens at the RF level, with the oscillators canceling each other out. Just so you know, I could be completely wrong. :D

As to "why" run multiple tuners, if you A/B tuners, or enjoy conducting shootouts, it's a must!

The local oscillator in most if not all FM tuners runs 10.7 MHz above the carrier
frequency, e.g. if you are tuned to 89.7 MHz, the oscillator is at 100.4 Mhz, which
will most likely kill any station at either 100.3 or 100.5 you might want to receive
on another tuner located in the vicinity. If you have an older tuner with continuous
tuning, you can set it so that the LO is exactly on the carrier frequency of the station
you 'want' to block. In principle, stations below about 87.9+10.7=98.6 MHz are
exempt from this effect as the LO cannot get lower.

Other more subtle effects involving harmonics and subharmonics may be involved
as well.

i've noticed that 'cancelling' effect too..:scratch2:

multiple tuners are fun tho :thmbsp:

Isn't this the fundamental principal of the heterodyne receiver?

That was my thought. The heterodyne effect gone out of control.

Here's some reading> http://en.wikipedia.org/wiki/Superheterodyne

The local oscillator in most if not all FM tuners runs 10.7 MHz above the carrier
frequency, e.g. if you are tuned to 89.7 MHz, the oscillator is at 100.4 Mhz, which
will most likely kill any station at either 100.3 or 100.5 you might want to receive
on another tuner located in the vicinity. If you have an older tuner with continuous
tuning, you can set it so that the LO is exactly on the carrier frequency of the station
you 'want' to block. In principle, stations below about 87.9+10.7=98.6 MHz are
exempt from this effect as the LO cannot get lower.

Other more subtle effects involving harmonics and subharmonics may be involved
as well.

Please help! I have a Harmon Kardon 330c receiver. After replacing the bad IF amplifier chip I do indeed receive FM, but in a very funny way. For instance, I receive the classical music station on 98.7 and 98.6MHz and also the 1000kHz AM radio station as interference. Could this be a difference signal that gets amplified through the IF mixer/converter stage?

Did you solder it well? A bad solder joint could be acting up. The fact that you are
receiving an AM station suggests there might be some undesirable non-linear effect
acting as an AM detector. It would help if you could describe what was the original
failure, what you did to diagnose it, and how you proceeded to replace that chip.
Good luck.

Why run two tuners at the same time?

Sometimes I run all three systems at once all balanced for a very special effect in the room. It can sound very beautiful and sometimes I feel bad for them being left out so I bring them all along. My main system has three tuners I can switch between including Internet Radio on the Duet. The other two systems are a Sansui G6000 whose tuner section is remarkable and my G-7700 with an external SAE TWO T14. So I can run all three systems and choose between three different tuners on the main system as well, including HD, Internet, the TU-717 or the DBX TX1. Its a blast!

Did you solder it well? A bad solder joint could be acting up. The fact that you are
receiving an AM station suggests there might be some undesirable non-linear effect
acting as an AM detector. It would help if you could describe what was the original
failure, what you did to diagnose it, and how you proceeded to replace that chip.
Good luck.

The longer story: Picked up a HK330C from Goodwill. Plugged it in and no fm, no lights no meter movement. Installed lamps times 5 and jerry rigged a battery tester to replace the meter which had infinite resistance and a broken wire under the magnification loupe. Used a signal injector and lost signal across IC202, a BA402 IC FM IF amp chip. Bypassed the chip using a capacitor between the input and output of the chip and voila, fm but much lower in volume and no stereo. A week later installed a chip obtained from ebay. However I installed it with a 7 pin inline socket made from a 14 pin DIP socket. So it plugs in like a vacuum tube. I get stereo and a decent volume on FM now. It sounds pretty good except for the 1000KHz signal from a 50KW radio station 7 miles away. Interestingly enough, I get two images of a signal about 0.1MHz apart both in stereo. Could the mixer/oscillator front end stage be causing some intermodulation distortion at exactly 1000 kHz causing reception of this strong AM station. The oscillator is off frequency by 0.4MHz or so. I will open up the case and get the oscillator dead on so the slide rule dial is calibrated in a week or so.

Quote:
Originally Posted by electroking
Did you solder it well? A bad solder joint could be acting up. The fact that you are
receiving an AM station suggests there might be some undesirable non-linear effect
acting as an AM detector. It would help if you could describe what was the original
failure, what you did to diagnose it, and how you proceeded to replace that chip.
Good luck.

The longer story: Picked up a HK330C from Goodwill. Plugged it in and no fm, no lights no meter movement. Installed lamps times 5 and jerry rigged a battery tester to replace the meter which had infinite resistance and a broken wire under the magnification loupe. Used a signal injector and lost signal across IC202, a BA402 IC FM IF amp chip. Bypassed the chip using a capacitor between the input and output of the chip and voila, fm but much lower in volume and no stereo. A week later installed a chip obtained from ebay. However I installed it with a 7 pin inline socket made from a 14 pin DIP socket. So it plugs in like a vacuum tube. I get stereo and a decent volume on FM now. It sounds pretty good except for the 1000KHz signal from a 50KW radio station 7 miles away. Interestingly enough, I get two images of a signal about 0.1MHz apart both in stereo. Could the mixer/oscillator front end stage be causing some intermodulation distortion at exactly 1000 kHz causing reception of this strong AM station. The oscillator is off frequency by 0.4MHz or so. I will open up the case and get the oscillator dead on so the slide rule dial is calibrated in a week or so.

Quote:
Originally Posted by electroking
Did you solder it well? A bad solder joint could be acting up. The fact that you are
receiving an AM station suggests there might be some undesirable non-linear effect
acting as an AM detector. It would help if you could describe what was the original
failure, what you did to diagnose it, and how you proceeded to replace that chip.
Good luck.

The longer story: Picked up a HK330C from Goodwill. Plugged it in and no fm, no lights no meter movement. Installed lamps times 5 and jerry rigged a battery tester to replace the meter which had infinite resistance and a broken wire under the magnification loupe. Used a signal injector and lost signal across IC202, a BA402 IC FM IF amp chip. Bypassed the chip using a capacitor between the input and output of the chip and voila, fm but much lower in volume and no stereo. A week later installed a chip obtained from ebay. However I installed it with a 7 pin inline socket made from a 14 pin DIP socket. So it plugs in like a vacuum tube. I get stereo and a decent volume on FM now. It sounds pretty good except for the 1000KHz signal from a 50KW radio station 7 miles away. Interestingly enough, I get two images of a signal about 0.1MHz apart both in stereo. Could the mixer/oscillator front end stage be causing some intermodulation distortion at exactly 1000 kHz causing reception of this strong AM station. The oscillator is off frequency by 0.4MHz or so. I will open up the case and get the oscillator dead on so the slide rule dial is calibrated in a week or so.

The load on the Mixer/Osc stage has changed since your repair and may have detuned the stage just enough to allow higher IM sidebands such as those you are seeing. The gain of those stages when tuned is usually set to minimize IM.

The load on the Mixer/Osc stage has changed since your repair and may have detuned the stage just enough to allow higher IM sidebands such as those you are seeing. The gain of those stages when tuned is usually set to minimize IM.

Thanks Ron,

I will tweak the oscillator stage while listening and try to get rid of the IM at 1000KHz. If it really gets to be a problem I will do the alignment the kosher way with a scope and signal generator.

Thanks Ron,

I will tweak the oscillator stage while listening and try to get rid of the IM at 1000KHz. If it really gets to be a problem I will do the alignment the kosher way with a scope and signal generator.

If you know how to align, you probably know about as much as I do
about FM tuners. Good luck!

If you know how to align, you probably know about as much as I do
about FM tuners. Good luck!

Actually I have the service manual and tried to follow the instructions, without the recommended scope and signal generator. Tuned the oscillator and got the dial calibration correct. There are two trimmer capacitors for the three ganged fm variable capacitor, yes just two. Interestingly enough when the trimmer capacitors have the resonant frequency about 1000kHz apart I can hear the am radio station at 1000kHz quite loudly through the headphones. However if I can ever have a quiet passage I can tune both trimmer capacitors for maximum output on the signal meter and minimum or null the AM station at 1000Hz. I have currently had some success, but am waiting for the singers on this classical station to quit singing so I can have a quiet background for a true null.

Actually I have the service manual and tried to follow the instructions, without the recommended scope and signal generator. Tuned the oscillator and got the dial calibration correct. There are two trimmer capacitors for the three ganged fm variable capacitor, yes just two. Interestingly enough when the trimmer capacitors have the resonant frequency about 1000kHz apart I can hear the am radio station at 1000kHz quite loudly through the headphones. However if I can ever have a quiet passage I can tune both trimmer capacitors for maximum output on the signal meter and minimum or null the AM station at 1000Hz. I have currently had some success, but am waiting for the singers on this classical station to quit singing so I can have a quiet background for a true null.

I was never formally trained in alignments, just have been learning from Audiokarma and following service manuals as much as possible with minimal equipment. Any help is truly appreciated. Many thanks for your advice.

Did you solder it well? A bad solder joint could be acting up. The fact that you are
receiving an AM station suggests there might be some undesirable non-linear effect
acting as an AM detector. It would help if you could describe what was the original
failure, what you did to diagnose it, and how you proceeded to replace that chip.
Good luck.
Many thanks to electrodeking and old tech, as the Harmon Kardon HK330c tuner section really sings nicely now!