Had a Technics SA-300 with no FM at all. Ran that down to this IC which is the final limiter and detector. Also handles the muting which I think it stupid to put in that chip. But I prodded a bit to make sure some dumbass 100K resistor isn't open somewhere.

Your chances of getting an AN377 are about as good as the lottery. So I used an NTE788 from our wonderful ESI out in Mrntor, Ohio. Now I got FM, which wss not before, but it is severely overmodulated. Nothing in the service manual indicates the coil alignment would affect gain. It is as if this chip was designed fro 25 kkHz deviation rather then 75, seriously. And how it connects to the tank circuit at the end makes me think it might be a slope detector, which ain't the best thing but maybe they fixed that somehow.

If anyone is familiar with this chip, or Technics of this vintage, I want your opinion on this NEW chip being bad. Wouldn't be the first time. What's more, sometimes with ECGs and NTEs and SKs there are problems due to specs. Been through that before. I got the coils tweaked where I have the tuning meter reading pretty right. The waveform at pin six is only wrong in amplitude. It has the correct DC value on it : 5.8 volts.

The old chip was missing some DC voltages. Really, since I got something out of it now I have not checked all the voltages on that IC. But does anyone think a DC voltage would cause this ?

This is like REALLY overmodulated. On rock stations clipping like 30 % of the time. Nice and symmetrical though. I look for failure modes, could that chip have blown something else to cause this ? I could not get the PDF on the AN377 but I found it in HTML and it looks right. I see nothing that could affect the gain of the FM detector like that.


thanks in advance if anything...

On 05/09/2014 06:50, wrote:
Had a Technics SA-300 with no FM at all. Ran that down to this IC which is the final limiter and detector. Also handles the muting which I think it stupid to put in that chip. But I prodded a bit to make sure some dumbass 100K resistor isn't open somewhere.

Your chances of getting an AN377 are about as good as the lottery. So I used an NTE788 from our wonderful ESI out in Mrntor, Ohio. Now I got FM, which wss not before, but it is severely overmodulated. Nothing in the service manual indicates the coil alignment would affect gain. It is as if this chip was designed fro 25 kkHz deviation rather then 75, seriously. And how it connects to the tank circuit at the end makes me think it might be a slope detector, which ain't the best thing but maybe they fixed that somehow.

If anyone is familiar with this chip, or Technics of this vintage, I want your opinion on this NEW chip being bad. Wouldn't be the first time. What's more, sometimes with ECGs and NTEs and SKs there are problems due to specs. Been through that before. I got the coils tweaked where I have the tuning meter reading pretty right. The waveform at pin six is only wrong in amplitude. It has the correct DC value on it : 5.8 volts.

The old chip was missing some DC voltages. Really, since I got something out of it now I have not checked all the voltages on that IC. But does anyone think a DC voltage would cause this ?

This is like REALLY overmodulated. On rock stations clipping like 30 % of the time. Nice and symmetrical though. I look for failure modes, could that chip have blown something else to cause this ? I could not get the PDF on the AN377 but I found it in HTML and it looks right. I see nothing that could affect the gain of the FM detector like that.


thanks in advance if anything...


Would getting hold of any of these schematics, so in circuit use of
AN377, be any help in adjusting response
KENWOOD KT313 AN377
KENWOOD KT313 AN377
KENWOOD T7 AN377
PANASONIC SA5170 AN377
PANASONIC SA400 AN377
PANASONIC ST9030 AN377
PANASONIC SA100 AN377

Had a Technics SA-300 with no FM at all. Ran that down to this IC which
is the final limiter and detector. Also handles the muting which I think
it stupid to put in that chip. But I prodded a bit to make sure some
dumbass 100K resistor isn't open somewhere.

Your chances of getting an AN377 are about as good as the lottery. So I
used an NTE788 from our wonderful ESI out in Mrntor, Ohio. Now I got FM,
which wss not before, but it is severely overmodulated. Nothing in the
service manual indicates the coil alignment would affect gain. It is as
if this chip was designed fro 25 kkHz deviation rather then 75,
seriously. And how it connects to the tank circuit at the end makes me
think it might be a slope detector, which ain't the best thing but maybe
they fixed that somehow.

If anyone is familiar with this chip, or Technics of this vintage, I
want your opinion on this NEW chip being bad.

I can't tell for sure, but it looks as if the NTE788 may be of the
similar design to (or even pin-compatible with) the Sanyo LA1230.

If so, it's a single-coil quadrature-detector.

I had a problem somewhat similar to yours with a family of
amateur-radio narrow-FM receivers a few years ago... the IF-detector
output started clipping at only about 2 kHz deviation, rather than
accepting up to 5 kHz or more cleanly. This sounded bad and
completely messed up the DTMF decoder.

The problem did turn out to be the coil... not its alignment, but its
in-circuit Q. The detector's output voltage depends on the amount
of phase shift introduced by the coil, at any particular amount of
frequency deviation, and the phase shift depends on the coil Q.

We talked to the manufacturer, and found that they'd had to change
suppliers for their detector coil a couple of years earlier when
the original coil was EOL'ed. Apparently the new coil they chose,
generated more phase shift per amount of deviation due to a higher Q
in the circuit. The Q is controlled by the impedances of the
reactances in the coil, and by the value(s) of the resistors(s) that
are shunted across one or more of the coil windings. My guess is
that the new coil had a lower L and a higher C than the
original... same resonant frequency, lower impedances, and thus the
existing shunt resistor had less effect.

We experimentally bridged the shunt resistor with a second one,
dropping the resistance and thus swamping the coil Q to a lower
value. The IF detector output dropped by about 50% at any given
amount of deviation, and the clipping was greatly reduced. A bit of
further experimentation and we were able to find a resistor value
which allowed the detector to handle 5.5 kHz of deviation before it
began to flat-top.

So, the problem turned out to be a one-resistor substitution in each
receiver... audio quality was greatly improved and DTMF detection
became reliable.

So, I'd suggest that you try an experiment of that sort... find the
resistor which shunts the coil, and decrease its effective value by
2:1 or 3:1 (just bridge it with another, for now) and see if this
un-clips the output.

The LA1230 data sheet comments that the chip's THD "depends on phase
linearity of the phase-shift circuit used"... I think this is alluding
to the same basic phenomenon.

Interesting. Being that getting parts for these old vintage things is not that easy, I might have to try that resistor trick.

Do you concur that the difference is in the IC ? If not that owuld mean two defective parts, which in low power circuitry like this, is kinda rare. If it is something with the coil, that means someone was listening to distortion and all the suddden it stopped working. The way it sounds right now I owuld have never had it switched to FM to even "wear it out" or whatever.

The print is available the Hifiengine if you'd like to have a look, or I could Dropbox it. There is another coil coming off the tank. The tank has two adjustments, but only two connections. Kinda makes me think adjusting that would affect the gain (output per deviation) but it doesn't seem to be working that way. When I first installed the IC, the tuning meter only deflected to the right, but by diddling I got it to balance out. Adjusting either coree doesn't seem to affect the output amplitude.


One thing of note, which might mean nothing, is the original IC was red inked. I know they don't do that for ****s and giggles. It may have been a custom run for Technics. If they used it in all their recievrs, maybe it is a custom IC with slightly different specs. They love doing that bcause it captivates the parts market. However I hold no hope of getting one from Panasonic at this point. Years ago they didn't even have parts for one of their damn RPTVs that cost two grand.

Know what ? Just because I wrote that, you probably CAN get it from them. I was fairly surprised that you can still get a four gang volume control for a Kenwood KR9400.

But not from Kenwood.

What really gets me is the quality of the front end in these old tuners. The new stuff seems to be junk. This thing is in a basement with absolutely no antenna connected and it is picking up stations. Newer recievers seem to get noting and that is with a wire on the antenna. I bet alot of them actually bat their ratings in sensitivity. Now instead of actually designing the thing they just buy a front end from China for like $3 if that, and address it by I2C.

I got a newer Technics stand alone tuner. This thing has it's own powers supply and even an AC outlet on the back, OF A TUNER. It has a rated sensitivity of 0.9 uV which is I think about half of the rating of this 300, and the 300 gets better reception. Even though distorted, it is getting more stations. this has been the case with several vintage recievers and tuners I've worked on recently.

Thanks for the tip. Now to figure out what value of resistor.

"Would getting hold of any of these schematics, so in circuit use of
AN377, be any help in adjusting response "

Thamks, I'll have to give a couple of those a look. Technics is Panasonic and their manuals quite frankly suck usually. I remember fixing their bigscreens, not only was the service menu very unfriendly, but the manual was not clear, with instructions to get into service mode many pages away. **** like that.

I will definitely have a look at that Kenwood manual provided Hifiengine or someone has it. If so I will take a look before doing the resistor trick.

Thing is, on these things I don't like to diddle alot. Bust that core or something and you're screwed. Think the IC might be hard to get ? HAHAHAHA.

Thanks.

In article ,
wrote:

Do you concur that the difference is in the IC ?

I think that's the likeliest thing. The two IC designs probably have
different "phase shift, to output voltage" sensitivities. The tank
circuit which was used with the original quadrature detector (a
two-coil type) is probably not quite what the new detector IC was
designed to use... and so a slight change in the tank Q might be all
that you need.

You might be able to research this if you care to. Look up the specs
for the tank coil with the AN377 used in the receiver. Then, look up
the specs for the tank coils suggested for use with the NTE chip, or
with the Sanyo or similar single-coil detectors. With lots of luck
and effort you might be able to compare the coil specs or sample
circuits and see where the differences lie.

Or, just try a swamping resistor and see if it makes the
difference... if so you'll know where the problem lies.

The print is available the Hifiengine if you'd like to have a look, or I
could Dropbox it. There is another coil coming off the tank.

Yeah, that was one of the significant changes in quadrature detector
designs over the years - getting rid of the need for the second
(usually fixed-value) inductor in the tank circuit.

The tank
has two adjustments, but only two connections. Kinda makes me think
adjusting that would affect the gain (output per deviation) but it
doesn't seem to be working that way.

No, I don't think it would... or, at least, not a big one. The two
adjustable cores (or trimmers) in the tank would adjust the resonant
frequencies of each part of the tank... but I think that any change in
the Q would be relatively minor. The Q for each of the two halves of
the tank transformer is going to be set by the values of its reactive
components, compared to the (external) resistor which is shunted
across them. To make a big change in the Q and phase shift (which is
what I think you need to do) without changing the resonant frequency
(which needs to remain at the IF frequency) you'll have to play with
the resistor.

What really gets me is the quality of the front end in these old tuners.
The new stuff seems to be junk.

A lot of people agree with you. There's a great deal of enthusiasm
out there for the "golden age of analog" FM tuners... expecially those
with real air-variable capacitors. A lot of 'em have better
sensitivity and selectivity than you'll find in modern products (in
which the FM section is almost an afterthought). Modern receivers
often tend to emphasize DSP and effects and 587-channel operation, and
cut corners on the basics :-(

On 05/09/2014 23:44, wrote:
Interesting. Being that getting parts for these old vintage things is not that easy, I might have to try that resistor trick.

Do you concur that the difference is in the IC ? If not that owuld mean two defective parts, which in low power circuitry like this, is kinda rare. If it is something with the coil, that means someone was listening to distortion and all the suddden it stopped working. The way it sounds right now I owuld have never had it switched to FM to even "wear it out" or whatever.

The print is available the Hifiengine if you'd like to have a look, or I could Dropbox it. There is another coil coming off the tank. The tank has two adjustments, but only two connections. Kinda makes me think adjusting that would affect the gain (output per deviation) but it doesn't seem to be working that way. When I first installed the IC, the tuning meter only deflected to the right, but by diddling I got it to balance out. Adjusting either coree doesn't seem to affect the output amplitude.


One thing of note, which might mean nothing, is the original IC was red inked. I know they don't do that for ****s and giggles. It may have been a custom run for Technics. If they used it in all their recievrs, maybe it is a custom IC with slightly different specs. They love doing that bcause it captivates the parts market. However I hold no hope of getting one from Panasonic at this point. Years ago they didn't even have parts for one of their damn RPTVs that cost two grand.

Know what ? Just because I wrote that, you probably CAN get it from them. I was fairly surprised that you can still get a four gang volume control for a Kenwood KR9400.

But not from Kenwood.

What really gets me is the quality of the front end in these old tuners. The new stuff seems to be junk. This thing is in a basement with absolutely no antenna connected and it is picking up stations. Newer recievers seem to get noting and that is with a wire on the antenna. I bet alot of them actually bat their ratings in sensitivity. Now instead of actually designing the thing they just buy a front end from China for like $3 if that, and address it by I2C.

I got a newer Technics stand alone tuner. This thing has it's own powers supply and even an AC outlet on the back, OF A TUNER. It has a rated sensitivity of 0.9 uV which is I think about half of the rating of this 300, and the 300 gets better reception. Even though distorted, it is getting more stations. this has been the case with several vintage recievers and tuners I've worked on recently.

Thanks for the tip. Now to figure out what value of resistor.


If you do any core twiddiddling, mark and note the "o'clockness" and
depth gauge the depth, beforehand , so you can at least get back to
where you started. A slight heating of the core with an iron tip may get
over any threadlock

I wound up with a 681 ohm resistor to correct the gain. then the tuning meter didn;t wor alomst at all. I removed a 330 ohm across it and shunted a ten K going to it with another ten K. got it to move wlel enough but it will not go both ways.

then, something is different with the muting, so I had to disable that, but the thing actually works acceptably. The tuningmeter is not centered, and tuning it you can tell it is not how it should be, but it picks up stations in a basement with a piece of wire. It works well enough.

I looked at the prices these things are bringing and well, that is good enough. Just tell the buyer the FM isn't quite right. It doesn't hav muting anymore because I disabled it to be ablre to switch it to stereo.

That is one of my biggest pet peeves about Technics, ganging the mone stereo switch with the muting. You now, I oiwn it and I will decide when to switch to mone on a weak signal. And who knows, I might have an extra Dolby decoder around, and those thigs are great for FM if you now how to set them.

But I shipped it. the sensitivity is good, once you get it tuned it sounds fairly clear although I am sure it does not meet the FM THD specs. But there is nothing I can do. Unless I can get the original private spec IC, this is the end of the road. So we get less money for it.

Sometimes it works that way. I got ore toime into it than I should but so what, I ma not under the gun here. Plus it comes out in the wash. We got lucky on a few other units. Now the idea is to get them sold. Iam kinda surprised at how fast some of this vintage sells.

The new **** must be pretty bad. Like all bells and whistles but no REAL sound. And I have worked on some of it. I do not want it. Like a 7.1 channel Sony, I would not take it for free if you brought it to my front door. Same with th new Pioneers, Onkyos, just about all of them. All been bought out.

Yup, 587 channels of junk.

I would really have liked to get the old Technics working really right, but oh well. I simply cannot have 100 hours in it. And I cannot make a custome AN377 with red ink on it.

Now that I think of it, in Panasonic equipment when I saw a chip with red ink on it people told me you cannot use the regular part, it HAS to come from them. And it will not come soon.

I always tried to tell the people that it was them who ****ed them over, not me. A manufacturer back then counts on XC amount of the time they do not believe me. Playing the odds. But when they take it to another shop.. And alot of the time I was the next shop.

I did cost some of these companies some bransd loyalty, and they had it coming.

On 6/09/2014 10:07 AM, David Platt wrote:


A lot of people agree with you.

**There are a lot of idiots out there too.


There's a great deal of enthusiasm
out there for the "golden age of analog" FM tuners... expecially those
with real air-variable capacitors.

**Yep. Some were very good. Some were crap. They drifted off station and
offered poor specs compared to many modern tuners. In terms of cost, the
modern tuners beat the pants off the old ones.


A lot of 'em have better
sensitivity and selectivity than you'll find in modern products (in
which the FM section is almost an afterthought).

**That is very much a generalisation. A good quality modern tuner can
provide performance which will exceed that of a good quality old tuner.
I have a selection of quite good old tuners (Yamaha T2, Yamaha T7,
Marantz 125, etc). I also have a much more modern Denon TU1500. It
anihilates the old tuners in every way. Sensitivity, selectivity,
distortion, sound quality, stability and, most critically, cost. Even
better, the TU1500 can be purcahsed very inexpensively, because every
man and his dog are dumping tuners to buy DAB+ models.


Modern receivers
often tend to emphasize DSP and effects and 587-channel operation, and
cut corners on the basics :-(

**Again: Very much a generalisation. When a company like Denon decides
to build a modern, good quality tuner, it can do so at reasonable cost
and offer very high levels of performance.


--
Trevor Wilson www.rageaudio.com.au

"
A lot of people agree with you.


**There are a lot of idiots out there too. "

Well at least you put the too on the end.

"**Yep. Some were very good. Some were crap. They drifted off station and
offered poor specs compared to many modern tuners. In terms of cost, the
modern tuners beat the pants off the old ones. "

Wait, we are not talking form the 1960s here. these htings were pretty refined. Even back then they had an adapted quartz lock instead of AFC to permanently ban drift. Plus, they generally knew what they were doing about thermal drift. I've had plenty of 1970s tuners and almost never had a problem with drift.

Tuners underwent a change around then from a narrow band detector and a wide band IF to wider band detector and a narrower, or at least better slopd IF. those ceramic filters were coing into vogue. Fact is, even though they did improve performance, they saved the manufacturers money.

"**Again: Very much a generalisation. When a company like Denon decides
to build a modern, good quality tuner, it can do so at reasonable cost
and offer very high levels of performance. "

You are talking about Denon here. You listed some good tuners you had. Those are not quite average.

But I'll tell you what RALLY beats the pants off the old tuners - manufacturing cost. I got a Technics which I consider half decent. It is standalone digital, actually has an AC outlet on the back. I forgot the model right now but the rated sensitivity is 0.9 uV. Not THAT tuner picks up as wlel as these old ones.

Thing about specs on things like this is the rule is to meet or exceed. If they rat the sensitivity at 1.5 uV and you test it and find it is 1.2 uV, you going to call them and complain ? "Sure Mr. ****ing add whatver adjective here, we'll send you out one that isn't as good right away".

With the techniques of the day, though they could get damn good performance, they could not always guarantee it. How many units did Hifi mag test that were more power, lower distortion and better FM than the manufacturer claimed ? Quite a few. Not all actually, but for a unit not to meet its rated specs was like a judge getting overturned by a higher court. Looks very bad and demands a response.

Does anyone test this stuff these days ?

But anyway, with the modern methods, you are not going to have all that many units exceeding specs by much. they are already too close to perfection, like in the IF filtrs, the digital detectors and all that.

A good analogy would be amps. Amps, including those in recievers could usually be expected to produce like 40 % mmore power than their rating. Some were almost double, but that was kinda rare. (actually a newer line of Protonss or something did that but they were junkbecause they were underbuilt)

Anyway, with modern transistors and/or ICs, they got perfect linearity to the rails. In the old days with the older circuitry they had a hard time keeping it linear all the way, so the outputs needed a littl headroom in the voltage department. You could crank them quite a bit higher, and if you were into loud that was good. Less clipping.

However you might be listening to say 2 % THD, below the clipping but more than the rated THD. Many people cannot har 2 %, and many speakers are ovr 2 % at higher listening levels.

Now look, I am not talking $30,000 systems here, I am talking good quaality but cheap enought that people will buy.

You go in there with say $800 for a new stereo, that includes at least reciever amd speakers or tuner and amp and speakers. I think what you could get in 1975 for that money was better than now.

A realy good modern tuner ? Luxman ? Hafler ? Sure. Except I don't listen to the radio. All my music is on the computer. Ha, now that I think of it there is this Iheartradio on the nett I guess I can listen to the radio on, so, I dunno.

So yeah, they got better specs but only because they can guarantee them. but the fact is that the FETs in the front end have not improved all thatt much - except in noise. tha tis a factor about where you can put it in the circuit. Right in front ? you need the very best ones. On a manufacturing level at any given price you can get a certain guaranteed noise figure. We ight be talkng a dollar. That is alot for one part. Now an equivalnt is just pennies. The whole front end for most of this stuff iss probably three bucks outtaa China. Just program something to tell it what to tune and the IF is yours.

When you talk the tuners you've had, the more modern ones, those are probably meticulously designed, the front end designed in house, **** like that. Not much off the shelf.

There is a big difference.

On 9/09/2014 3:19 PM, wrote:
" A lot of people agree with you.


**There are a lot of idiots out there too. "

Well at least you put the too on the end.

"**Yep. Some were very good. Some were crap. They drifted off
station and offered poor specs compared to many modern tuners. In
terms of cost, the modern tuners beat the pants off the old ones.
"

Wait, we are not talking form the 1960s here. these htings were
pretty refined. Even back then they had an adapted quartz lock
instead of AFC to permanently ban drift. Plus, they generally knew
what they were doing about thermal drift. I've had plenty of 1970s
tuners and almost never had a problem with drift.

**As national service manager for Marantz Australia, during the mid-late
1970s, I recieved all the troublesome jobs from all over the nation.
That included a bunch of drifting tuners. They were a colassal PITA.
Sourcing and replacing appropriate caps in FM stages was nonsensically
time-consuming. In one instance, I duplicated the then, new, Model 2600
quartz locking system and installed it into a particularly troublesome
one. Worked a treat and was a quick fix. I was a happy chappy when
Marantz went all digital.


Tuners underwent a change around then from a narrow band detector and
a wide band IF to wider band detector and a narrower, or at least
better slopd IF. those ceramic filters were coing into vogue. Fact
is, even though they did improve performance, they saved the
manufacturers money.

"**Again: Very much a generalisation. When a company like Denon
decides to build a modern, good quality tuner, it can do so at
reasonable cost and offer very high levels of performance. "

You are talking about Denon here. You listed some good tuners you
had. Those are not quite average.

**THAT was my point. I own some VERY fine, VERY expensive old analogue
tuners. The modern, digitally tuned, Denon blows them away. In every
meaningful way.



When you talk the tuners you've had, the more modern ones, those are
probably meticulously designed, the front end designed in house, ****
like that. Not much off the shelf.

**There is nothing special in the Denon. It is bog-standard stuff, well
executed, with careful attention to detail. The Yamahas and the Marantz,
OTOH, go to heoric lengths (particularly the Marantz 125) to obtain
inferior performance to the much cheaper Denon TU1500.


There is a big difference.


**Yes, there is. Download the service manual for the Marantz 125 and see
what incredible lengths Marantz went to in order to achieve mediocre
performance, compared to the Denon.


--
Trevor Wilson www.rageaudio.com.au

On Thu, 4 Sep 2014 22:50:50 -0700 (PDT), wrote:

Had a Technics SA-300 with no FM at all. Ran that down to this IC which is the final limiter and detector. Also handles the muting which I think it stupid to put in that chip. But I prodded a bit to make sure some dumbass 100K resistor isn't open somewhere.

Your chances of getting an AN377 are about as good as the lottery. So I used an NTE788 from our wonderful ESI out in Mrntor, Ohio. Now I got FM, which wss not before, but it is severely overmodulated. Nothing in the service manual indicates the coil alignment would affect gain. It is as if this chip was designed fro 25 kkHz deviation rather then 75, seriously. And how it connects to the tank circuit at the end makes me think it might be a slope detector, which ain't the best thing but maybe they fixed that somehow.

If anyone is familiar with this chip, or Technics of this vintage, I want your opinion on this NEW chip being bad. Wouldn't be the first time. What's more, sometimes with ECGs and NTEs and SKs there are problems due to specs. Been through that before. I got the coils tweaked where I have the tuning meter reading pretty right. The waveform at pin six is only wrong in amplitude. It has the correct DC value on it : 5.8 volts.

The old chip was missing some DC voltages. Really, since I got something out of it now I have not checked all the voltages on that IC. But does anyone think a DC voltage would cause this ?

This is like REALLY overmodulated. On rock stations clipping like 30 % of the time. Nice and symmetrical though. I look for failure modes, could that chip have blown something else to cause this ? I could not get the PDF on the AN377 but I found it in HTML and it looks right. I see nothing that could affect the gain of the FM detector like that.


thanks in advance if anything...


You can buy an AN377 brand new on EBay for $5.00 from a reputable U.S.
seller. (In San Jose Ca.) Chuck

On Wed, 10 Sep 2014 08:50:54 +1000, Trevor Wilson
wrote:

On 9/09/2014 3:19 PM, wrote:
" A lot of people agree with you.


**There are a lot of idiots out there too. "

Well at least you put the too on the end.

"**Yep. Some were very good. Some were crap. They drifted off
station and offered poor specs compared to many modern tuners. In
terms of cost, the modern tuners beat the pants off the old ones.
"

Wait, we are not talking form the 1960s here. these htings were
pretty refined. Even back then they had an adapted quartz lock
instead of AFC to permanently ban drift. Plus, they generally knew
what they were doing about thermal drift. I've had plenty of 1970s
tuners and almost never had a problem with drift.

**As national service manager for Marantz Australia, during the mid-late
1970s, I recieved all the troublesome jobs from all over the nation.
That included a bunch of drifting tuners. They were a colassal PITA.
Sourcing and replacing appropriate caps in FM stages was nonsensically
time-consuming. In one instance, I duplicated the then, new, Model 2600
quartz locking system and installed it into a particularly troublesome
one. Worked a treat and was a quick fix. I was a happy chappy when
Marantz went all digital.


Tuners underwent a change around then from a narrow band detector and
a wide band IF to wider band detector and a narrower, or at least
better slopd IF. those ceramic filters were coing into vogue. Fact
is, even though they did improve performance, they saved the
manufacturers money.

"**Again: Very much a generalisation. When a company like Denon
decides to build a modern, good quality tuner, it can do so at
reasonable cost and offer very high levels of performance. "

You are talking about Denon here. You listed some good tuners you
had. Those are not quite average.

**THAT was my point. I own some VERY fine, VERY expensive old analogue
tuners. The modern, digitally tuned, Denon blows them away. In every
meaningful way.



When you talk the tuners you've had, the more modern ones, those are
probably meticulously designed, the front end designed in house, ****
like that. Not much off the shelf.

**There is nothing special in the Denon. It is bog-standard stuff, well
executed, with careful attention to detail. The Yamahas and the Marantz,
OTOH, go to heoric lengths (particularly the Marantz 125) to obtain
inferior performance to the much cheaper Denon TU1500.


There is a big difference.


**Yes, there is. Download the service manual for the Marantz 125 and see
what incredible lengths Marantz went to in order to achieve mediocre
performance, compared to the Denon.


There was a huge old Pioneer receiver that came into Best Buy's main
repair center that had tuner drift which previous techs gave up on. I
replaced the npo caps once, and other components, but the drift
continued. I finally found a npo cap that caused the frequency to
drift exactly in the opposite direction at the same temperatures as
the original drift. I played the unit for 2 weeks and shipped it. It
never came back. Chuck