[Hammarlund] ITT Modified SP-600

[k2cby]

The ITT SP-600 that I have contains four modifications identified by rubber
stamps on the chassis reading "MV1" through "MV4.": MV1 The 6BA6 at V11 was
changed to a 6BE6 configured as a product detector; MV2 The 6AL5 (V14) was
replaced by the former V11 (a 6BA6) and the IF driver function re-positioned
to that location; MV3 The 6V6 output tube (V17) was replaced by a 6SN7 of
which half was used as an audio amplifier and half as a diode-connected
triode substituting for the disconnected V14 (The noise limiter was
sacrificed.); MV4 the 6C4 3.5 MHz oscillator (V8) was replaced by a 6EA8
half of which was used as an oscillator and the other half as a buffer. The
audio output transformer was replaced.

 

The inputs for both the 1st Mixer and the 3rd Mixer (BFO) (but not the 3.5
MHz  oscillator) were brought out through coax jacks.

 

This is the condition of my SP-600 "as received." I assume all these
modifications were made by (or for) ITT, but subsequent modifications may
have been made after the receiver passed out of ITT ownership.

 

There is no indication that the 455 kHz IF was taken out of the receiver to
be further down-converted. The only output is audio.

 

Miles B. Anderson, K2CBY
16 Round Pond Lane
Sag Harbor, NY 11963
Tel.: (631) 725-4400

Fax.: (631) 725-2223
e-mail: k2cby at optonline.net