[Heathkit] coils for SB610 and SB620

[Tom NØJMY - AAR7FV]

Okay.  For Mike and anybody else interested: I've done a little more 
research and have come up with further info regarding the difference 
between the coils in a SB-620 vs. those in a HO-13.  The "dummy" 
terminal on the SB-620's coil *is* used as a solder tie-point, though it 
is *not* connected to the coil itself.  The resistors which make up the 
voltage-divider for the sweep-width switch are attached to it, as is the 
lead to the switch itself.   The HO-13 coils (40-588 or -589) do not 
have this "dummy" terminal, but are electrically identical to the 40-775 
or -776, respectively, in the SB-620.  I *assume* they could be used to 
replace these coils - you would just have to provide an isolated 
terminal somewhere nearby as a substitute for the "dummy".  And it seems 
logical that these coils from a SB-620 would be a drop-in replacement 
for the corresponding ones in a HO-13.

Of course, this is all based on the shaky premise that you can find any 
of these coils in the first place.

Oddly enough, my manual lists terminal lug #2 as the "dummy", but the 
engineering blueprints list it as terminal #4.  Oh, well.

FWIW, the coils for the HO-13 are 40-588 (455-1681 kHz.) and 40-589 
(2075-3395 kHz.)..  The coils for the SB-620 are 40 -774 (not sure what 
i.f. range, apparently replaced by the -808? or was it the -807?), -775 
(455-1000 kHz), -776 (3000-3395 kHz.), -807 (5200-6000 kHz.), and -808 
(1600-2445 kHz.).

73,
Tom

Tom NØJMY - AAR7FV wrote:
>>
>> BTW, the only difference between the 620's 40-775 and the HO-13's 
>> 40-588 is that the 40-588 has three terminals, where the 40-775 has a 
>> fourth "dummy" terminal that wasn't connected to the coil.  Offhand, 
>> I don't know if the "dummy" lug was used for something such as a 
>> tie-point terminal for something on the SB-620, or if it was just 
>> there because that's the way the vendor made them.