[Amps] SB-220

[Jeff]

  Hello all,
I just powered up a Heathkit SB-220 and I am trying to load it up on 3.770 MHz. I believe I am loading it up correctly, here are the results:
Mode: CW
Power into amp: 65W
Plate current: .480
Grid current: .180
High Voltage (keyed): 2150
Power out :760W (read with a bird peak reading meter)
This seems OK on CW but when I switch to high power SSB the amp makes a "spitting"noise when I transmit.
 I am driving the amp with an Icom 761 and have the ALC hooked up from the 761 to the SB-220 and I was wondering if I needed to connect the ALC lead from the exciter to the amp if I never drive it with more than 100 watts in SSB.
Thanks in advance, 73 Jeff  KA0JW