HAMMARLUND SP600

MANUAL ISSUE IDENTIFICATION


ISSUE-TO-ISSUE CHANGES (INCOMPLETE)

1 - 2

1.  Remove C101 (3.5MHz osc trim)
2.  Add E5 (1-pin terminal strip) and L53 between C147 and J2 (IF OUT)
3.  Add F2 (1/4A, B+, leaded inline fuse under the chassis)
4.  Change crystal filter spoilers R45/R46/R47 from 22/100/1K to 240/1.1K/18K
5.  Fix misprint: T7 and T8 part numbers swapped

2 - 3

1.  Remove J4 (RELAY)
2.  Move F2 into the formerly spare fuseholder on the rear panel
    Add Spare Fuse clip on the rear panel
3.  V7 (GATE) changed from -10V fixed bias to 390 ohm unbypassed cathode bias
	 a. Remove R34 and C100
	 b. Add R112 (390 ohms)
    This reduces the bias voltage from -10V to about -4V, and
    increases the gain and signal-handling ability (the former
    in spite of the unbypassed resistor).
4.  Reduce V11 (DRIVER) bias from -10V to -7.5V
	 a. Add R113 (330K)
5.  Remove PHONO input
	 a. Remove E1 (2-screw terminal strip on rear apron)
6.  Add external AGC input and diode output
	 a. Add E3 (4-screw terminal strip on rear apron)
	 b. Add C164 (430pF) and R111 (100K)
	 c. Disconnect R63 from R64 and bring out to E3, where
	    they are bridged again
7.  Reduce IF OUTPUT level, eliminate BFO from IF OUTPUT
	 a. Move C145 from V11/V12 pins 5 to T5 secondary
	 b. Change T5 was 31102-G1 now 31102-G2 (T4 too, but it's irrelevant)
    This reduces the IF output voltage from 20-something to about 1.
8.  Bypass AGC delay voltage
	 a. Add C162 (.022) from V14 pin 5 to ground
9.  More bypass on switched RF B+
	 a. Add C163 (.25)
10. Remove superfluous coupling cap
	 a. Remove C45, on V5 pin 7 - this node is always
	    floating or returned to ground
11. Change R103-R110 from 510 ohms to 27K
    At the low-frequency end of these bands, this increases
    the Q, which tightens the primary-secondary coupling,
    which increases the sensitivity and broadens the response



WHICH ISSUE IS YOUR RADIO

(Note: E13 is located underneath, on the side of
the bandwitch turret shield next to one of the
filter chokes.)

1. PHONO terminals
 1a. No inductor on IF OUT jack: Issue 1
 1b. L53 on IF OUT jack: Issue 2
2. DIODE/AVC terminals
 2a. No big power resistors under the power transformer: Issue 3
 2b. Two big power resistors
  2b1. Linear E13/7-wire tuning unit: Issue 4
  2b2. Block E13/6-wire tuning unit: Issue 5

Military nameplate clues:

1. R-274A: Issue 2 (there are no military Issue 1's)
2. R-274C
 2a. S/N below 470: Issue 3
 2b. S/N 470 to 1569: Issue 4
 2c. S/N 1570 and up: Issue 5
3. R-320A: Issue 2
4. R-483: Issue 2
5. R-483A: Issue 3

The R-483 and R-483A are SP-600-J rather than JX.
The R-320A is SP-600-J plus an IF GAIN control.