On Dec 18, 2024, at 11:16?AM, Joseph K7CBR via groups.io <k7cbr@...> wrote:

The new blower moves over twice the air of the factory blower through the same sk406 chimney. I did the direct comparison using a hand held anemometer... held at the same location and distance above the outlet of the SK-406 chimney. I forgot now what the original velocity and CFM values vs. new ones were/are. I measured this to avoid any confirmation bias. It was nice to see Jim (VE7RF) confirming my findings. As I stated a long time ago, it is not enough to have one person just say it/measure it. Even though I was careful to do empirical measurement.

Tuesday, December 10, 2024 at 11:33:34 AM EST, Richard Knoppow via groups.io <1oldlens1@...> wrote:

? ? ? Does changing the idle current affect the distortion? If this is
the grid bias with no drive it is the operating point of the amplifier.
If I understand what you are doing correctly (and I may well not be) the
bias establishes the operating point of the amplifier so increasing bias
toward cut off, i.e. more negative, moves the amplifier toward Class B.
That would certainly reduce dissipation in the absence of drive.
? ? Another thought: Does not the tapering of the chimney at the top
restrict air flow? It should increase velocity at the plate seal but is
a constriction so might reduce overall air flow. Maybe there is
something here I am not getting.

On 12/10/2024 7:46 AM, Jim VE7RF via groups.io wrote:
> On Mon, Dec 9, 2024 at 05:17 PM, Joseph K7CBR wrote:
>
>? ? <Well Senor Jim... I was wondering if you had made the change yet on
>? ? the L4B... .. What was the before and after result? Cooling, noise,
>? ? and so on...
>


--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998