[Moon-net] ALC spikes

[Leif Asbrink]

Hello Ken,

> I have a TS2000 which I use - no sequencer - the rig 
> has a built in set of parameters which only allow the RF 
> to appear at the ant socket AFTER the relays have gone over. 
> Also I believe that ALC is not used in the circuit - but 
> even if it is then I have no problems - so far.
The TS2000 happens to be a rare example of a transceiver
with a decent ALC. Look here for performance at full power on
144:
http://www.sm5bsz.com/dynrange/rs04/ts2000_50600050_100w_144_cwk.htm

> Better to use rig at its design power and to attenuate 
> the it power to the PA requirement - OK not easy I 
> know - but best solution.
This is a good recommendation for a TS2000 as you can see here:
http://www.sm5bsz.com/dynrange/rs04/ts2000_50600050_25w_14_cwk.htm
http://www.sm5bsz.com/dynrange/rs04/ts2000_50600050_100w_14_cwk.htm

Full power is usually a good solution because transceivers are 
typically designed to not have much gain margin at full power on
144 MHz. I can not say for sure it is always true however and
I could imagine that higher gain margins might occur in more
modern units that use more modern silicon.


The below table is from 14 MHz:

----------------------------------------------------
Setting      CW       Carrier      SSB        PTToff
            (W)        (W)         (W)          (W)
   H         75         49         108          120
   5         55         33.8        78          116
   2         16.4       9.5         32.4         97
   1         10.0       5.0         11.3         79
   L          5.2       2.5          9.0         46

Table 2. Peak power levels at the antenna connector. 
----------------------------------------------------

This is an IC202MKIIG. For details, look here:
http://www.sm5bsz.com/dynrange/pulse.htm

If you run this unit at full power on 14 MHz and select an attenuator
that gives nominal power from a power amplifier with the key pressed
in CW, the peak power would be 53% higher than nominal power on
the keying transcients. Presumably transistor power amplifiers
can be driven with 3 dB excess power without damage, but local
amateurs would suffer from the keying clicks over a wider frequency 
range.

73

Leif / SM5BSZ