[ARC5] Lopsided modulation

[Dennis]

Let’s drop the PA filtering explanation, guys.  It’s not even worth a back of the envelope calculation.  Not in the ballpark.

There is plenty of incidental FM going on in our MOPA’s.  Enough to support phased addition and subtraction of sidebands as the probable cause.  Here are some numbers taken a few years ago from my T-22.

7.05MHz
50W plate input (500V at 100mA)
30W output
Regulated supplies on osc, screen, and plate.
Minor mods to PA tank. Otherwise stock.

2.1KHz pull on key down with a selected high gm 1626.  2.5KHz pull with an average gm osc tube.

The resulting chirp is minimal because the change caused by osc loading occurs quickly.  There is only a mild thermal tail that one hears.

Now toss in plate modulation and about double those incidental frequency deviations.

Dennis AE6C

Sent from my iPhone

> On Feb 28, 2018, at 7:09 AM, hwhall at compuserve.com wrote:
> 
> Perhaps the next time they are observing the lopsided sidebands, the transmitting station can wiggle the final tuning & then they can see if there is any correlation between the imbalance and the tuning. Nothing like experimentation.....
> 
> Wayne
> WB4OGM
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