[R-390] Component Replacement Ideas

[Perry Sandeen]

Fellow Listers,

Wrote: In my opinion, folks are overly ambitious about component replacement in the R-390 series receivers. 

I respectfully disagree.

Most of one’s time is in the dis-assembly, cleaning, and re-assembling of the receiver.

Wrote:  Routine mass component replacement is extremely time consuming, is generally unproductive, <parse>  

Actually it is faster to remove and replace all the resisters and capacitors at one time (which are generally 40 to 50 years old) than to have to go back time and again.

<parse>  and risks collateral damage to the equipment. 

All of life carries risk.  Knowledge, care, planning and knowing one’s personal limitations minimize disaster.

Wrote: Frankly, it borders on the obsessive, particularly in the case of resistors.  In most cases, I would suggest replacing any 1/2 watt 10% resistor reading 20% or more off center--otherwise, leave well enough alone.

Three points.

1.  Carbon composition resistors have three major problems.  One they drift far off of value. Second they have a doughnut shaped warm-up and cool down curve. Third their resistance varies according to their operating temperature.

2.  Metal film replacements are quieter, smaller, and cost far less than carbon comps (AND they have NO inductance at the frequencies of our receivers).  In fact you can hardly buy them anymore as they are far inferior to the alternatives.  The same holds true for modern ceramic disc and silver dipped mica capacitors

3.  Frankly too is my reaction to your judgment on what is obsessive.  There is a vast difference from a receiver  ”working” and “the best performance that can be achieved”.  Mundane care gets the former and dedication gets the latter.  If you read ER magazine, the Y2KR2 manual as well as looking in the past reflector posts you will find numerous documented R390A improvements involving component and tube replacements.  Science contradicts your technical opinions.  

Personally, I’d appreciate not having anyone using the judgment phrase “it borders on the obsessive” describing anyone of our radio activities.  To me it was at the least, very poor taste.

Regards,

Perrier