[R-390] Replacing resistors

[Perry Sandeen]

List,
About 10 or so years ago I made a resistor buy for list members.  At that time I was able to buy from Mouser.  Now the will sell you through hole resisters we use in 5,000 reals only.
Looking around I found Digi-Key now sells 1/2W 1% MF resistors in small quantities. The "low cost" ones are 19 cents and the "high priced' ones are 29 cents in single units.  They have a very good break point from IIRC 5 of each or more.
Doing some rough (very) math it appeared one could replace all the 1/2W resisters in a SP600 and just a bit more for the R39x series.
A member previously brought up that we have "Boltzems Constant" (sp) for noise in resisters and seemed to believe that MF resistors were unnecessary It's true, we still have that constant but also the added noise from different constructions.
Most B/A receives we like are now 70 to 75 years old. CC resistors of the vintage are now notoriously value changed or are unstable.  When these B/A's were made 1 or 5% metal film resisters cost a kings ransom. 
When we remove the variables of CC resistors we can then work on refining performance.
One also might want to consider replacing all the .01 ceramic bypass resisters do to their age.  Buying in 50 or 100 units (remember you have more that one radio) brings the unit price down considerably,  I have hade excellent results with the Murata brand.
Of course then there is the SP 600 wire......
Regards,
Perry KM6FQV

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