Powering up “mothballed” solid-state equipment

Discussion in '"Boat Anchor" & Classic Equipment' started by W9CYS, Oct 5, 2019.

ad: L-HROutlet
ad: l-rl
ad: Left-2
ad: L-MFJ
ad: Left-3
ad: abrind-2
ad: Subscribe
  1. W9CYS

    W9CYS Ham Member QRZ Page

    I’ve picked up a car full of old gear 1970s-90s from an elderly uncle who doesn’t have much of a memory. He couldn’t recall if the equipment was working when he packed things up. I offered to help he and my aunt recover some $ for the stuff but I’d prefer to assess radio condition rather than give it away at untested prices.

    I have a variac I’ve used to safely and slowly light up old Drake and Hammarlund tube gear. However, this lot I picked up includes some all solid-state radios, including a Tentec 509/405 amp and a Drake SPR-4. Since this solid-state isn’t subject to the HV found in tube gear, I wanted to understand the process to safely light up this gear.

    I’ve inspected the radios for physical evidence of any failure and found none. It is still best practice to bring voltages up slowly? I can use the variac with the SPR-4 and can adjust a DC supply to slowly bring the 509 up to 13.8VDC.

    Any other practices I need to be aware of “waking up” 13.8VDC gear?

    Thanks and 73,


  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    If it is real old 12 Volts should do the trick.

    You can put a light bulb / Headlamp in series with power to bring it up slow.

    Don't forget the fuse.
  3. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Personally, on solid state gear I wouldn't try to bring the supply voltage up slowly. Between voltage regulation on the rig's supplies and things like minimal levels for any digital logic (e.g. displays) I wouldn't try to ramp up the main DC supply voltage.

    As Don suggests above, the old series lightbulb trick using a big bulb like a car headlight would help by protecting your DC power supply if it doesn't already have good crowbar protection but if you have a supply well protected against over current situations then I'd just connect the rig and fire it up.
    K0UO, N0TZU and NE1U like this.
  4. K6BSU

    K6BSU Ham Member QRZ Page

    It is unusual for filter caps in a 12 volt supply to cause problems. The low voltage isn't so stressful as in high voltage power supplies.
    You might experience "drying out" of the electrolytics. This would only cause poor filtering and maybe some "hum" in the speaker ot in the transmitted carrier.
    K0UO likes this.

Share This Page