Date   

Re: Last Call - Yahoo Groups

newaag
 

How about a DVD of files? Everything FM Tuners related would be a massive amount of data to download, maybe 5 GB.
If everyone who received a DVD made 2 or 3 and passed them to the next requester, it would take it off one person doing it all.
And be easier to do regions, like Europe.
Also, reminder, Wilson Logan posted (in this group), a link of files and photos in October 2019. I think he also has or had a download for the messages at FMTuners. And there was another post following with more online goodies.
Bob


Re: Last Call - Yahoo Groups

Janos avl2
 

as " But once downloaded, the files can be shared and viewed by others.  "

would someone be so nice if already downloaded to put it for share somewhere (that people like me with no computer with administrator rights, using only company laptop, could have it) ? thank you

János, Hungary


Re: KT-615 Help Request

newaag
 

Yep, sadly it is THOSE units that sometimes end up for sale on EBay. With words like "front panel lights up, no way to test", or worse, "everything works great", then..."gee, it worked fine for me, must have been damaged in shipping".


Re: [buy] Last Call - Yahoo Groups

eric benson <frwhl@...>
 

Buy


On Mon, Dec 2, 2019 at 6:47 PM, newaag via Groups.Io
<newaag@...> wrote:
Friends of this group over the long haul may remember other splinter groups create by some of the founding members and moderators at Yahoo. There are no plans to move these over here, but there is still the opportunity to save the photos, files, and messages for your unlimited use into the future.
But you better hurry, as after mid-December 2019, the historical content of all Yahoo groups will be gone forever. You do this by purchasing PG Offline, and downloading the groups content. This is just a FYI, and a brief list of some of those other groups started by Jim, Tim, Bob, and others related to audio and FM Tuners. 
diy_audio_tweaks (the Jim Rivers "mods" group)
fm_antennas (files and pics only)
HDRadio (Tim's group)
highend_radio (German discussion, but many nice files and photos)
Kenwoodaudio (may be moved if we make it..)
fm-mpx (may be moved if we make it..)

The next four were mostly FM Tuner files only, no discussion. But packed with lots of great FM tuner manuals and info. 
FMTunersArchive
FMTunersArchiveII
FMTunersArchiveIII
FMTunersPhotosand4Sale
I have no affiliation with PGOffline, I'm just a long time user, and highly recommend it for $25.
http://www.personalgroupware.com/
You do need to be a member of each Yahoo group to download the messages and files. But once downloaded, the files can be shared and viewed by others. Archived Message db4 files can be shared/imported by non-members that use the PGoffline software. Files and Photos are directly viewable with no special software. 
 
Bob


Re: KT-615 Help Request

 

Thank you
Good Logical Advice.

I think there have been a few hackers into this unit be fore me...
There seems to be lots of footprints left behind...

ggdavis




On Monday, December 2, 2019, 6:08:28 PM EST, newaag via Groups.Io <newaag@...> wrote:


You can fix the scratching by cleaning the RF gangs. Do not spray the whole thing like a switch! Use a toothpick type of applicator and get the cleaner/lube only into the area where the shaft wipers (usually copper) wipe on the center shaft. Than work it back and forth from 88-108 a few times. If really bad, it may need more than one treatment. 

On the other stuff - you need to use non-metal tools to adjust ferrites, usually plastic. Metal tools will cause them to break/crack, then jam. No fix, except to remove them, and if possible, glue them back together. When I did this I un-soldered the whole coil and worked on it from both top and bottom. I never did save on, used spare ferrites from junk tuner/receivers. Cheap 70's receivers with blown power outputs are good candidates. Surplus electronics places may sell ferrite slugs, but I don't think there is a reliable source (at least that I know of). Some of the Ham radio guys may have more info - search on Google. Like this
https://www.electronicsurplus.com/catalogsearch/advanced/result/?name=&sku=&short_description=ferrite+slug&surplus_alt_part_number=&surplus_part_number=

or this
https://www.surplussales.com/Inductors/FerPotC/FerPotC-1.html

Bob


Last Call - Yahoo Groups

newaag
 
Edited

Friends of this group over the long haul may remember other splinter groups create by some of the founding members and moderators at Yahoo. There are no plans to move these over here, but there is still the opportunity to save the photos, files, and messages for your unlimited use into the future.
But you better hurry, as after mid-December 2019, the historical content of all Yahoo groups will be gone forever. You do this by purchasing PG Offline, and downloading the groups content. This is just a FYI, and a brief list of some of those other groups started by Jim, Tim, Bob, and others related to audio and FM Tuners. 
diy_audio_tweaks (the Jim Rivers "mods" group)
fm_antennas (files and pics only)
HDRadio (Tim's group)
highend_radio (German discussion, but many nice files and photos)
Kenwoodaudio (may be moved if we make it..)
fm-mpx (may be moved if we make it..)
DIOmods (Bob's early DIO DAC mods group)

The next four were mostly FM Tuner files only, no discussion. But packed with lots of great FM tuner manuals and info. 
FMTunersArchive
FMTunersArchiveII
FMTunersArchiveIII
FMTunersPhotosand4Sale
I have no affiliation with PGOffline, I'm just a long time user, and highly recommend it for $25.
http://www.personalgroupware.com/
You do need to be a member of each Yahoo group to download the messages and files. But once downloaded, the files can be shared and viewed by others. Archived Message db4 files can be shared/imported by non-members that use the PGoffline software. Files and Photos are directly viewable with no special software. 
 
Bob


Re: KT-615 Help Request

newaag
 

You can fix the scratching by cleaning the RF gangs. Do not spray the whole thing like a switch! Use a toothpick type of applicator and get the cleaner/lube only into the area where the shaft wipers (usually copper) wipe on the center shaft. Than work it back and forth from 88-108 a few times. If really bad, it may need more than one treatment. 

On the other stuff - you need to use non-metal tools to adjust ferrites, usually plastic. Metal tools will cause them to break/crack, then jam. No fix, except to remove them, and if possible, glue them back together. When I did this I un-soldered the whole coil and worked on it from both top and bottom. I never did save on, used spare ferrites from junk tuner/receivers. Cheap 70's receivers with blown power outputs are good candidates. Surplus electronics places may sell ferrite slugs, but I don't think there is a reliable source (at least that I know of). Some of the Ham radio guys may have more info - search on Google. Like this
https://www.electronicsurplus.com/catalogsearch/advanced/result/?name=&sku=&short_description=ferrite+slug&surplus_alt_part_number=&surplus_part_number=

or this
https://www.surplussales.com/Inductors/FerPotC/FerPotC-1.html

Bob


KT-615 Help Request

 

Mucho appreciation for the FM tuner enthusiasts!  You guys hooked me about two years ago....

I dived in....and now have a batch of tuners that I am anxious to revive and audition....  The "Live from Here" show with Chris Thile broadcast live on NPR 6pm ET Saturdays is just the most fantastic program audio that keeps me addicted to FM audio potential!

A KT-615 Kenwood keeps tantalizing me with incredible sounding cymbals thru its "Pulse Count Dectector"... 

But.... there are issues the FM MPX decode:  The chip was not working.... Checked the Pilot Osc frequency,  and found 100 kHz...  The 360 pF Suflex polystyrene cap measures at 360pF out of circuit,  but I replaced it with a 470 pF mylar cap,  and was able to dial in 76 kHz for the MPX....  and stereo decoding was working again...

But.... This is where I plead for remedial educational help..... I am UNABLE to align the front end...

1.   The C3 trimmer on the 5 gang variable cap cannot be dialed in... twisted too tight... and gives no more
2.  The L1 coil is jammed and the tuning slug is cracked... maybe due to fixing glue
3.  The L3 coil is jammed... cannot get it to move...


So,  Massive DC scratching noises emminate while tuning,.   Sensitivity is waaay down,....  

Questions...

How can you release the ferrite tuning slugs from a glue jam, without damaging the plastic tube coil form...

Is there a source for replacement RF & IF tuning coils.... The Kenwood schematics do not provide actual inductance values!

How do you restore the Cap trim range on the variable 5 gang  tuning capacitor

Very much enjoy reading the dialog on this forum!!

Gregory Davis WR1Z




Re: Kenwood KT-8300/9900 Tuner

newaag
 

Yes, there is one op-amp that oscillates in the KT-8300 if replaced with a faster one like OPA-2132, but my recall is OPA-2134 works fine. My testing shows you can use the faster one there if you add a 3-5pf cap across the feedback resistor in those 2 circuits (it's a dual op-amp). The oscillation is easy to see, for me it was in the 5-8 kHz range and was a big single spike on an FFT screen. You could also hear it. This is the op-amp directly after the detector output. There is a LOT going on in the analog section of that tuner after the detector, including a discrete via switching FETs MPX decoder section. For the record, the FM detector has 2 outputs as well. It's easy to get lost. I did. 
Bob


Re: Posting Files

Paul
 

look in the files section I uploaded everything else I had specific to the SG80


Re: Kenwood KT-8300/9900 Tuner

rick.savas@...
 

Hi Joseph,

Re-drawing the schematic is a time consuming task, good for you, what are you using to draw the schematic?
The one scan I have is pretty good just that when you print them out they do not line up so fiddling with the print settings can make them line up. Not as tedious as re-drawing the whole schematic again.
One thing I noticed is that they use an RC4558 opamp, which is dual uA741, for ICg11,13, well that is probably one of the first mod's I could suggest to make. Just have be careful with oscillation using a faster part, since they did not use good local device decoupling. They used a metal can package, made the footprint a DIP. All the opamps on my spare X05-1350-10 pcb are JRC4558T dated 8003,8007
Since I have a spare X05-1350-10 pcb that is easy for me to look at if you need some help. I got it for a good price since many components are obsolete. I see they have a couple of parts tack solder on the back. I'd have to check if they are in the schematic.ceramic disc 473Z from #32 to ground plane for the section IF. The resistor is covered in glue, I'd have to measure that, from CN1(red wire) to R158, the other side of R158 goes to CN3-green. Of course CN1,2,3 are not labeled on the schematic :) More tracing, CN1,2,3 have a common connect on the pcb, which is the red wire, +15V. They do not show common on the schematic however if you follow CN1, it goes to B* at #21, I think, you know it is hard to trace with the dos we have. Best I can do for now.

Good luck Rick


Re: Kenwood KT-8300/9900 Tuner

Peter Wieck
 

For the record, I am so very glad that there are members here with enough time and thoughtfulness to dig so deep and provide key information for the rest of us!

Thank all of you for your efforts!

Peter Wieck
Melrose Park, PA 


Re: Kenwood KT-8300/9900 Tuner

Joseph Strickland
 

I have been re-drawing the schematic for the KT-8300/9900 models. The copies available on the internet are very poor scans of the original schematic. In the process I discovered that the caption about the signal level applied during AM alignment on the schematic page did not agree with that mentioned on page 7 in the AM alignment instructions. Page 7 was correct in stating that the signal level applied was at 30% modulation. On the schematic page(s) the caption about AM alignment says 30% DEV. or deviation. Deviation applies to FM modulation not AM modulation. I have corrected this on the schematic I am redrawing.

There are some areas of the original schematic that have trace lines so close together that they become quite blurred due to poor scans. This is particularly true in the area between ICg9 and Qg15 and the IF Trigger control. Also the ellipses that contain voltage measurements are just black with no discernible information in them. I see no notation on the schematic as to whether the voltages measured are with or without signal applied to the FM RF input terminals or the AM RF signal input. I need to examine statements on other pages of the manual to see if the conditions are stated. I would expect the condition to be with no signals being applied.

I need to open up my tuner and take time to measure voltages and develop a table for reference. I have deleted all the notations as to voltages in the schematic ellipses. I did leave the notations as to voltages provided to the power supply rails. Currently with the schematic page set for 11" X 17" and 300dpi plus color for the modifications a fellow member of this group added, the file size for that page is 48.2MB. I hope to get a print out at C size which will be 22" X 34" so I can work on the tuner without having to use glasses to read the fine print. After that I will see if I can reduce the resolution of the 11" X 17" drawing to get it to a lower file size that still will convey all the needed information without compromising the visibility of the information.

Joe


Re: Bruce Carter grunge filter

John Carpanini
 

Hi Radu,

  Yes , you are correct, each rail should be decoupled to Ground, not each other.  In effect the "filter" is shunting all that high frequency hash out into the ground plane.  Please post back with your results.
Regards
JohnC


Re: Bruce Carter grunge filter

Radu Bogdan Dicher
 

On further examination of the circuit, the op amps are ran in balanced PS mode. I may have to revise how I'm "grunge-decoupling" this. 

BTW - the ZD801 choice is very marginally sound - in my bench tuner, the zener was out of spec by about half a volt upwards, which therefore supplied the HA11211 (absolute maximum Vcc 13V) with just about 13.5V. I replaced it with a 12V zenner - in lack of a better matching part - but I came to think, btw, that the service manual incorrectly calls for +12V in the emitter of Q801. It should be +13V, to match the -13V on the negative rail. Either way, the zenner is spec'd too close to frying IC106 for comfort. I guess some drop over L102 dips it under 13V. Has everyone else noted this? 

Thank you,
Radu. 

On Sun, Dec 1, 2019 at 8:32 PM Radu Bogdan Dicher via Groups.Io <vondicher=gmail.com@groups.io> wrote:
Hi John,
And thank you for pitching in. In the case of this tuner, with its TA7136P, I went between pins 4 and 7 of each op amp with my "caps pack" - as visible in the picture enclosed. 

However, unless I triggered something totally unrelated, this seems to turn off any signal coming into the tuner (I get no indication of my generator's signal in by watching the tuning meter as I go over the adjusted frequency). The AP box doesn't sense audio signal coming in (the level adjusting relays would go off as I dial onto the generator frequency and past it). 

Busy with family and different projects (tube integrated indefinite lender for family member), so I didn't get back to this, but that's what's been going on the other day.

Thank you,
Radu. 

On Sat, Nov 30, 2019 at 11:07 PM John Carpanini <jacarp@...> wrote:
Hi Radu,
  If I'm understanding you correctly yes all of the caps are in parallel going from B+ to ground.  Ideally you want the hot side of the cap with the shortest possible lead and let the ground side run as needed.  Here's what Bruce had to say from one of his earlier missives:

"In decoupling applications, I have long been an advocate of multiple capacitors - each creating more rejection in the stop band. At the point of power entry,

an aluminum or tantalum with a resonance of about 100 kHz, then near IC's a 0.1uF for 10 MHz, in parallel with a 0.01uF for about 70 to 80 MHz, in parallel
with an NPO/COG 1000pF for about 400 MHz, in parallel with a 33pF NPO/COG for 2.4 GHz (to get rid of cell phone trash). The three ceramics create about
equally spaced nulls on a log frequency plot, keeping overall stop band impedance very low. Of course I'd love to see a capacitor manufacturer put all
of those inside a single package, but it won't happen because practically nobody knows how to properly decouple circuits - preferring to use a single 0.1uF - a
legacy value from the middle 1960s when computer boards ran at about 1 MHz.

 

I recommend a small series resistor in line with the + and - supplies, 1 to 10 ohms or so, with the bypassing right at the op amp power pin.  This vastly improves power supply rejection ratio of the op amp.  Also, at minimum, 33 pF NPO in parallel with the 0.1 uF cap to get rid of cell phone interference.  Adding other caps in parallel such as 1000 pF NPO will improve FM rejection in the audio circuit."

Regards
JohnC


Re: Bruce Carter grunge filter

Radu Bogdan Dicher
 

Hi John,
And thank you for pitching in. In the case of this tuner, with its TA7136P, I went between pins 4 and 7 of each op amp with my "caps pack" - as visible in the picture enclosed. 

However, unless I triggered something totally unrelated, this seems to turn off any signal coming into the tuner (I get no indication of my generator's signal in by watching the tuning meter as I go over the adjusted frequency). The AP box doesn't sense audio signal coming in (the level adjusting relays would go off as I dial onto the generator frequency and past it). 

Busy with family and different projects (tube integrated indefinite lender for family member), so I didn't get back to this, but that's what's been going on the other day.

Thank you,
Radu. 

On Sat, Nov 30, 2019 at 11:07 PM John Carpanini <jacarp@...> wrote:
Hi Radu,
  If I'm understanding you correctly yes all of the caps are in parallel going from B+ to ground.  Ideally you want the hot side of the cap with the shortest possible lead and let the ground side run as needed.  Here's what Bruce had to say from one of his earlier missives:

"In decoupling applications, I have long been an advocate of multiple capacitors - each creating more rejection in the stop band. At the point of power entry,

an aluminum or tantalum with a resonance of about 100 kHz, then near IC's a 0.1uF for 10 MHz, in parallel with a 0.01uF for about 70 to 80 MHz, in parallel
with an NPO/COG 1000pF for about 400 MHz, in parallel with a 33pF NPO/COG for 2.4 GHz (to get rid of cell phone trash). The three ceramics create about
equally spaced nulls on a log frequency plot, keeping overall stop band impedance very low. Of course I'd love to see a capacitor manufacturer put all
of those inside a single package, but it won't happen because practically nobody knows how to properly decouple circuits - preferring to use a single 0.1uF - a
legacy value from the middle 1960s when computer boards ran at about 1 MHz.

 

I recommend a small series resistor in line with the + and - supplies, 1 to 10 ohms or so, with the bypassing right at the op amp power pin.  This vastly improves power supply rejection ratio of the op amp.  Also, at minimum, 33 pF NPO in parallel with the 0.1 uF cap to get rid of cell phone interference.  Adding other caps in parallel such as 1000 pF NPO will improve FM rejection in the audio circuit."

Regards
JohnC


Re: Bruce Carter grunge filter

John Carpanini
 

Hi Radu,
  If I'm understanding you correctly yes all of the caps are in parallel going from B+ to ground.  Ideally you want the hot side of the cap with the shortest possible lead and let the ground side run as needed.  Here's what Bruce had to say from one of his earlier missives:

"In decoupling applications, I have long been an advocate of multiple capacitors - each creating more rejection in the stop band. At the point of power entry,

an aluminum or tantalum with a resonance of about 100 kHz, then near IC's a 0.1uF for 10 MHz, in parallel with a 0.01uF for about 70 to 80 MHz, in parallel
with an NPO/COG 1000pF for about 400 MHz, in parallel with a 33pF NPO/COG for 2.4 GHz (to get rid of cell phone trash). The three ceramics create about
equally spaced nulls on a log frequency plot, keeping overall stop band impedance very low. Of course I'd love to see a capacitor manufacturer put all
of those inside a single package, but it won't happen because practically nobody knows how to properly decouple circuits - preferring to use a single 0.1uF - a
legacy value from the middle 1960s when computer boards ran at about 1 MHz.

 

I recommend a small series resistor in line with the + and - supplies, 1 to 10 ohms or so, with the bypassing right at the op amp power pin.  This vastly improves power supply rejection ratio of the op amp.  Also, at minimum, 33 pF NPO in parallel with the 0.1 uF cap to get rid of cell phone interference.  Adding other caps in parallel such as 1000 pF NPO will improve FM rejection in the audio circuit."

Regards
JohnC


Bruce Carter grunge filter

Radu Bogdan Dicher
 

Hody all,
And Happy belated Thanksgiving to all those celebrating.

Needing some clarification on Bruce Carter's grunge filter. My understanding is this is a decoupling solution on steroids, covering just about anything that can infiltrate DC these days. Therefore, if intending to apply this, I'd get the power supply rails of the AF stages decoupled with something like 0.1uF/0.01uF/1nF/33pF in parallel, as close to the op amp (if applicable) as possible, on Vcc/GND. 

I am applying this to a Gamma I and get cancellation of signal in (no movement on meters, etc.). I don't think I am shorting anything to ground by adding these parts. 

Attaching pictures - I hope they hop on. 

Thank you for your input!
Radu.


Re: Posting Files

 

@Paul - I would appreciate a chance to view the Sencore Tech Tips.  


Re: Denon tuners

A- Mon
 

I would agree. The 1500RD was my first 'proper' tuner; I bought it new and was impressed with the sound at the time, but compared to the other tuners I have now from Technics, Audiolab, Rega, Linn (to name a few) it sounds flat and lacklustre. Also it only took a few years for the tuning knob to stop working reliably. Likely just needs cleaned, but I was usually happy to use the remote. Another bugbear for me is the very long mute time between each tuning step; not so good for dx'ing though I found the sensitivity to be fairly good. Aesthetically I am loath to sell the 1500RD just because I have always thought it looks very classy; from the all-metal case construction to the large bright blue dot-matrix display I just love looking at this tuner.

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