Boat Anchor Repair

Discussion in 'General Electronics Chat' started by jmoffat, Dec 20, 2015.

  1. jmoffat

    Thread Starter Member

    Jul 18, 2012
    A while ago I bought an Hallicrafters S-53A shortwave radio. It covers 530 KHz to 54 MHz. It works poorly on the broadcast band and worse on the upper frequencies. Lots of strange noise and dead spots as I tune across the dial

    I have found that 2 of the carbon composition resistors have changed vale dramatically. The 27 ohm resistor associated with the oscillator tuning circuit is now 83 ohms. The 330K screen grid resistor on the mixer tube is now 1.36 Meg. All the other resistors are within about 20% . I will replace the 2 obviously bad resistors but I wonder if replacing anything more than 10% off nominal value is worth the effort.
    Now about the capacitors, I will replace all those waxy tubular capacitors but just how reliable are those square capacitors with the colored dots? The ceramic disks?

    Manual and schematic
  2. sailorjoe


    Jun 4, 2013
    TUBES! I haven't worked with tubes since I built my first ham radio in high school.
    Your radio is around 40+ years old, right? And it hasn't been used for quite some time, right?
    Are you sitting down? Fix the resistors as planned. Then replace all the electrolytic capacitors. You could remove and test them, but these type had a tendency to dry out over time. Most people just replace them all with known good ones. If you haven't done so already, test the tubes in a good quality tube tester that can tell you whether the tube is good, bad, or in between. Tubes can sometimes leak some molecules of air into their vacuum over a long period, and that will certainly cause noise in the signal. There are multiple groups of people around the country devoted to restoring old radios, and you might find their expertise quite valuable. Google "tube radio restoration" and see where that leads.