Some weeks ago, on the contest reflector, there was talk of the Icom
IC-706's brief, but severe, initial power spike when first keying the rig
into transmit --using an oscilloscope trace, some had measured as high as
150 watts -- due to ALC characteristics. A couple folks felt ALL Icom
transceivers had this "defect"; others had not seen it on certain models.
It was advised NOT to use the '706 with ceramic-tube amplifiers such as the
Alpha 87A, which could be damaged by this spike.
My delightful new '706MKII exhibits that problem: I don't have a 'scope,
but there's no question a huge over-power spike appears on my PEP-reading
Yaesu YS-60 power meter on initial key-down. Meter characteristics cause
the power measurement to be elevated for about a second, after which the
meter drops down to the real output. (When I switch to "average" power
reading, of course, the spike disappears.) I have *NOT* noticed such a
spike with my IC-735.
I'll accept that this brief excess of power could definitely damage
delicate-grid ceramic tubes, but should I worry about driving (a) my
solid-state IC-2KL? and (b) a 2x572B SB-200?? In the case of the '2KL,
which only requires ~25 watts drive, I *could* put in a 3dB attenuator to
buffer the spike; I do not have such drive overhead with the SB-200.
TU! 73 Gene K7dBV genewill@ordata.com
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