KENWOOD KT-880D


rross7677@sbcglobal.net
 

SEASONS GREETING

I have a 880D that I would like to do the cap mod described on the tuner info web site.

Has anyone experience with this tuner/mod?

Bob


johnacarp <jacarp@...>
 

Hi Bob,

You may want to have a look at Brian Beezley's thoughts on the 880D. He has some pretty good info there. Link below:

http://www.ham-radio.com/k6sti/kt-880d.htm

If I was redoing it today I would use 11DQ10 schottky diodes in the power supply and bump C54 to 47uF Nichicon "ES" series if I couldn't find a BlackGateG N . Other than that it still holds up pretty well.

Regards
JohnC


I have a 880D that I would like to do the cap mod described on the tuner info web site.

Has anyone experience with this tuner/mod?

Bob


Robert C. Chambers <rchamber@...>
 

...have a look at Brian Beezley's thoughts on the 880D.
I wonder if he had any "thoughts" about how it *sounds*...he don't say.


istvanmihalcz@...
 
Edited

After recaps. Now has good stable image, wide soundstage, middrange is pretty good, nice tight bass and fairly deep, and the treble is clear.
Next mod can be the output buffer. On KT880D is no any, but in KT5020, which is almost same, has made with NJM4560, but are recommended to be used OPA2604.


John Carpanini
 

I added the buffer a while back and it worked out just fine.  I attached some pictures and the schematic I worked from, in case that helps.  The original design was done by our own Ray McDonald (RFM).  As you can see in the schematic, it implements a balanced power supply and uses a 2604 OpAmp.  All the pics and the schematic ate posted in the Photo section here:

Schematic & Pics

Regards
JohnC


istvanmihalcz@...
 

Thanks, John,

The next update will cover that. Why did you make a separate power supply for the output buffer with transformer?
After recapping a heard a strange stereo just at one classical music station (this noise cannot be heard at any other stations, including also other classical ones), looks like when you heard just the difference, but after approx 10 hours of listening, disappears. Now is very good.

I have plenty of radios, but from this era (end of 80's - beginning of 90's) this tuner is the most listenable.
I wonder what and how will improve the listening impression the buffer on the output. 

Regards, István


John Carpanini
 

Hi Istvan,
  The added power supply provides balanced power rails, both + & - for the Opamp, which the factory PS does not.  I believe that OpAmps operated in this fashion sound better than running them single sided.  Bass tighter and high end sweeter, IMHO.  Additionally keeping the load of the added OpAmp off the OEM supply , which it was not designed to support, can't be a bad thing.  Just my $0.02.

Regards
JohnC