Anything that represents a transmit non-linearity can cause splatter, and a very quick change in gain represents a non-linearity.
My ICOM 756Pro was one of those offenders that used an internal ALC to set the power level. The internal delay in the ALC caused nasty power spikes at the beginning of transmissions that kept tripping the overdrive protection on my TenTec ALS-500 solid state amp. It was a stupid system and I don't know if ICOM ever addressed it with their later rigs. Amplifiers that use screen grid tubes like the GU-74B also do not those fast leading edge power spikes, making me grateful for the way the K3 handles things. 73, Dave AB7E On 6/9/2012 7:03 AM, Jim Brown wrote: > On 6/9/2012 5:14 AM, Geoffrey Mackenzie-Kennedy wrote: >> the reason why a typical ALC can be responsible for splatter is because >> these ALC systems sample the output of an amplifier and/or exciter, and due >> to time delays cannot "throttle back" the drive power immediately. > The ONLY proper ways to set power output are 1) to turn down the > transceiver's output power by turning down the power control on the > transceiver; or 2) using a resistive attenuator (voltage divider) > between the transceiver and the amplifier. W8JI, who has designed a lot > of power amps, and, as part of that design work, has studied the > behaviour of lots of ham transceivers, has written an excellent and > detailed tutorial on this matter, and on how some ham transceiver ALC > systems badly misbehave, and NEED to use option 2. The K3 (and the > FT1000MP) do not have this problem, and work fine with option 1. > > > 73, Jim K9YC > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
