I wonder if we aren't simply looking at a porridge consisting of ALC
loop times, mixed with synthesiser (PLL) lock-up times.
The gentlemen in the East are continually embarrassed, and publicly
disgraced, in the pages of QST when the dear old leading dots, at 2000
dots per microsecond, get lost... This exceeds my CW ear, so I
personally couldn't care about a missing high-speed dot (or two).
Would much rather look after the +6 dB leading edge (specially on my 6m
neighbours' IC706).
Ian ZS6BTE
Steve Thompson wrote:
> In the FT990, there is a transistor which discharges a .22uF cap (fast
> attack) with a 1M resistor to +ve for slow decay. The high collector
> resistor provides nearly all the ALC loop gain. There is .1uF in series with
> 10k across the 1M, so the fast attack is delayed while this charges - the
> loop gain is 100x lower at the beginning of the attack transient. It makes
> for cute little spikes....
>
> I have a suspicion that this part of the radio was simply found to work,
> rather than properly designed.
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