Well the 5325B crystal oven heater resistance is lower than what the manual states (60Ω to 80Ω, I suspect it may have shorted turns.
David
Are you working in a semi-frigid shop like I usually prefer...? My cold-blooded nature does sometimes cause me similar confusion. I'd suggest that the more important indicator is of course how much current it draws; if it doesn't exceed spec then probably okay. If you could easily separate the oven from the crystal section (I know, not bloody likely), I'd try tapping on it while it's heating and look for current spikes.
Cheers,
mnem
Percussive maintenance is a time-honored diagnostic tool.
The shed temperature was about 17°C to 18°C, it was a bit lower at the weekend & last week at 15°C, I struggle to keep my hands from shaking if it gets too cold, no good if I want to solder or avoid shorting things with test probes.
As I have both the 5325A & B, some comparison measurements were taken for both the resistance & current draw of the crystal oven (I got too tired last night to post the results).
The oven heater resistance (at room temperature) was 49.6Ω for the 5325B & 80.6Ω in the older 5325A.
Current draw for the heater when powered up was approx 0.5A for the 5325B, it dropped & stabilised at 16mA after a while. The 5325A was approx 375mA at power up & stabilised at 45mA. I had to switch to a different meter as the Yokogawa doesn't have a mA range.
As I got distracted by the burnt components* & Gorilla bodges (thanks
Med) in the 5325A I haven't yet opened the faulty crystal oven assembly to see if the heater can be repaired or not, or if it's intermittent or burnt to a crisp, the manual does actually give a part number for the heater element (0410-0161).
*Hope I'm not putting BD off from wanting an older
hp counter, even if it's keeping him entertained.
David