ALC meter reading on HW-100 and SB-102

[Stewart D Lyon]

Hi Allen,

I have both a SB-101 & a HW-101 (and their schematics). In comparing the
two, RL1-1,9,5 of the HW corresponds to RL1-2,10,6 of the SB and is
located on the schematic near the power plug. On the HW, only the NO
contact hooks to the plug -- to pin 11 and grounds the linear relay on
xmit.  The swinger is directly grounded and the NC contact (pin 1) is
open (not to pin 8 of the power plug). The schematic I have on the HW-101
seems to have an error in that it shows this relay section in the xmit
mode.

Given all that, I'm not sure how the circuit works since pin 1 of the
relay is grounded on RECEIVE. The sequence apparently is to adjust for
zero on transmit using the zero adjust control then adjust the added pot
for zero on receive.

The zero adjust pot on the SB is 200 ohms (with a 330 in series) and on
the HW, 10K. I don't think adding a 2K resistor to ground on such a
low-resistance circuit would work.  It would take a fair amount of
experimentation to apply the HW-100 fix to the SB-10x.

Where is El Cajon??

73, Stu - W6CUX
Winnetka, CA
ARRL Life Member

On Sun, 13 Sep 1998 14:11:42 -0700 "Allen, KJ6XH" <mattall at FDA.NET>
writes:
>Hi Greenies!
>
>Problem: ALC reads below Zero on SSB transmit and low on
>voice peaks.
>
>Heath Tech Bulletin HW-100-18 addresses this problem for
>the HW-100 and says: "add a 2K ohm resistor or 10K trim
>control between lug 1 of relay 1 and the center lug of the
>S-meter zero-adjust control."
>
>Now! What about the same problem on the SB-102??
>The Tech Bulletins for the SB-102 do not appear to address
>this problem. The schematic suggests that lug 1 of relay 1
>may *not* be the same as for the HW-100.
>Any one have knowledge of this ALC situation on the SB's--
>and how to effect a cure?
>Thanks.
>Allen
>--
>73 de Rev. Allen, KJ6XH                   El Cajon, CA

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