Heathkit HW-101 Resistences on the final valve sockets

Discussion in '"Boat Anchor" & Classic Equipment' started by CS7AWB, Oct 30, 2021.

Tags:
ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: L-MFJ
ad: L-Geochron
ad: abrind-2
ad: Left-2
  1. CS7AWB

    CS7AWB XML Subscriber QRZ Page

    Hello all,

    I'm recovering an hw-101 it is now working ok'ish but, when i go to measure the resistences on the finals, they are not like in the manual, the results I have are

    V9
    1 2.8R
    2 0.8 R
    3 239k
    4 2.7R
    5 20k
    6 2.7 R

    V8

    1 2.7R
    2 0.8 R
    3 239K
    4 2.6 R
    5 20K
    6 2.7 R


    I've been checking the wiring and it seems fine,

    my finals are 6146B valves.


    what may be causeing the mismatch ?


    thanks

    Jorge
     
  2. WA0CBW

    WA0CBW Ham Member QRZ Page

    What mis match are you talking about?
    BB
     
  3. CS7AWB

    CS7AWB XML Subscriber QRZ Page

    The resistances that appear on the manual. are different from the one I have.
     
  4. CS7AWB

    CS7AWB XML Subscriber QRZ Page

    Can it be the multimeter ?

    voltages are coincident with the manual
     
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    I would lift one end of R953(should be 220K) and R920(should be 10k) as the resistance on pin 3 is almost 20% higher than I'd expect looking at the schematic and that sets the screen voltage. Your cathode resistor R917 may also be a bit high but that is very likely a meter accuracy issue unless you're using a good 4 wire ohm meter known to be good down to a 10th of an ohm or less.

    The most common problem I've seen throughout all of the HW-101 or similar SB-101, SB-102 circuitry is old carbon comp resistors that have drifted high in value. The tube resistance checks are a good starting point but often it requires unsoldering one end of a suspect resistor, lifting it so it's out of the circuit and then measuring its value.
     
    CS7AWB likes this.

Share This Page