[Boatanchors] OA2 Voltage Regulation Question

[wa9wfa]

Thanks everyone for all the input on the OA2 regulator tube.  I also chatted with a friend who said his HA-5 originally had an OA2 without enough voltage to keep it in regulation.  I looked at everything and conclude the tube is operating correctly.

I believe I found the true problem.  I am somewhat embarrassed to report that I forgot to test the tubes. I was looking through my notes and realized I hadn’t test the tubes beforehand.  Aw geez… And of course, two of them were low.  The 6U8 oscillator tube was very low, as was the mixer tube.  While I don’t expect a low emission mixer tube to affect frequency, the 6U8 sure does… I replaced the tube and all is well.  So while the OA2 was a boondoggle, I did learn more about the OA2 operation.  
I had a nice 20m CW QSO with the 2NT, HA-5, and 2-B/2-BQ station.  Signal sounded great.  What a delightful station! 

Thanks again.  I appreciate your help!  73, Scott WA9WFA

> On Sep 8, 2023, at 9:08 PM, Walt Cates <cateswa at msn.com> wrote:
> 
> 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/