[Hallicrafters] SX28 sensitivity

[Mike Everette]

Did you check the carbon resistors in the radio?

You probably should have replaced all of them.  I hate
to be the bearer of bad news, but in several Halli
receivers of that vintage, I have found more than half
the resistors to be way out of spec.  Typically, any
100K or higher resistors that have to carry any
current -- plate loads, screen dropping, voltage
dividers -- will read as much as 70 percent to 100
percent high.

These are not the only ones though.

Even if they check good when you check them as you
recap (I hope you checked them), they may go up in
value with further use.

Especially "bad" about this are the 1/3 or 1/2 watt
carbons that have "ribbed" bodies and look like they
have "caps" on the ends, looking sort of like a
miniature version of the caps that fit on a 3AG
cartridge fuse.  

Do some checking with an ohmmeter (very easy to do in
a tube rig) and I'll bet you find several bad ones. 
Realize that if you check a resistor and it reads
higher than it is marked, it is bad.  If it reads
lower, there might be something in parallel with it,
but the resistor should be easy to measure
nonetheless.

Hope you don't have to go back into hell (oops -- the
RF box).

The DeOxIt advice is excellent as well.

73

Mike
WA4DLF



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