[R-390] R-390/URR heater circuits.

[Renee K6FSB]

Bingo....helps mitigate AC Hum  due the high impedance of AC fil 
especially on the limiters.
thanks Jim S.
Renée

On 8/11/26 11:34 AM, Jim Shorney via R-390 wrote:
> Maybe this is relevant.
>
> https://www.wb4hfn.com/DRAKE/DrakeArticles/Why_8BN8-2B.htm
>
> On Tue, 11 Aug 2026 18:13:00 +0000 (UTC)
> Jim Whartenby via R-390 <r-390 at mailman.qth.net> wrote:
>
>> Fred and Renée Well yes and no WRT answering my question.   It is now my understanding that the heater power reduction was done to improve some aspect of using a triode as a diode.  I am not sure what circuit function is actually benefiting from this.  The noise aspect is a reasonable explanation for reduced heater power.