[Boatanchors] OA2 Voltage Regulation Question

[Walt Cates]

The max allowable change in voltage for the 0A2, with in the range of 5 to 30ma of anode current is 600 millivolts. 200 to 300 millivolts is well within spec.

C1A and C1B (on some schematics and parts lists C1 11uf and C32 4uf) are most likely causes of drift. Be sure to note the temperature compensation code of each capacitor.


 Walt Cates, WD0GOF
https://wd0gof.com/Hallicrafters

A majority of acceptance is not proof of correctness.


https://wd0gof.com/bible-study/commentaries/

________________________________
From: boatanchors-bounces at mailman.qth.net <boatanchors-bounces at mailman.qth.net> on behalf of wa9wfa <whitebear1122 at comcast.net>
Sent: Friday, September 8, 2023 8:16 PM
To: Boatanchors Mailman. Qth. Net <boatanchors at mailman.qth.net>
Subject: [Boatanchors] OA2 Voltage Regulation Question

For a properly biased OA2, what would you consider normal for changes in regulated voltage over small changes in load current.  I’m working on a Hallicrafters HA-5 VFO, and when I key the VFO, I’m seeing small changes in the OA2 regulated voltage (148V) on the order of 200-300 millivolts, and it’s kind of drifting up and down.  Is this normal? Now with that said, I need to yet investigate if the OA2 is supplied with enough current, and what the input voltage looks like while being keyed.  I’m hunting down minor changes in output frequency when it’s keyed.  Thanks. 73, Scott WA9WFA

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