[Amps] drive power

[rgroh at swbell.net]

I think the problem being alluded to is a burst of RF (at full output) from the transmitter/transceiver which happens before the ALC can cut in and reduce it to the proper level.  If the designer does pay attention, it is easy to have happen - the RF turns on abruptly while the ALC loop has too long of an attack time so there is a bit of time before the ALC loop can come into play (delay time in the ALC loop). It certainly could, in some units, be exaggerated when running at lower RF levels because you have further for the ALC loop to ramp the output back.

The latter problem is also affected by the fact that the RF amplifier has a maximum RF level (i.e. the RF is clipped or limited). If your normal RF level is just a bit below the maximum then the 'burst' is not (relatively speaking) not that much higher. For example, if your amplifier is only capable of 150 W  and you normally run 125W then the burst is only 25W possible.  If, on the other hand, you are running 25W normally then the burst is 125W!  Quite a difference.

Hope this helps a bit.

73
Bob, WA2CKY
Blue Springs, MO. 64014

----- Original Message ----
From: Win <w0lz at winlyn.us>
To: Amps at contesting.com
Sent: Monday, March 19, 2007 10:17:08 PM
Subject: Re: [Amps] drive power

I hate to come back to this subject, but I am not sure I understand the 
problem.  Is the overshoot a product of the ALC outputted from the exciter 
to the amp, or is it caused within the transceiver at significantly reduced 
power settings.

In either case I should be able to see the overshoot if I put a scope across 
the meter in my power meter.  Is that correct?.

I currently reduce my FT-1000MKV from 200 to 50 watts, when driving my old 
SB-220 amp on CW.

Win, W0LZ 

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