SB-101 1st IF cathode resistor question

[Ed Lambert]

When you said there were 66 ohm resistors installed, I thought I'd look
at my manual because there's no 66 ohm carbon resistor made.  The three
values close are 56, 62, and 68.

My manual, dated 11-25-66 shows 56 (not 66) ohm resistors in those
positions in both the schematic and the construction pages.

Since the screen voltage is higher than expected, I would start looking
at resistor values around there also....  especially the 22K 1 watt to
B+.

Ed
K1ZOK



On Wed, 19 Mar 2003 23:07:53 -0600 "Randall C. Iliff"
<riliff at COMMSPEED.NET> writes:
> Greetings fellow Heath fans,
>
> I'm still chasing the SB-101 low output on SSB, low S Meter reading
> gremlin(s?) and came across something odd:
>
> The schematic and circuit description show two 47 ohm resistors
> (R104 &
> R105) that form a voltage divider in the cathode to ground path of
> 1st IF
> Amp V3.  The resistance chart shows an expected 105 ohms from the
> cathode
> (pin 7) to ground.
>
> The assembly manual shows to place 66 ohm resistors at those
> locations, and
> that is what is currently mounted on the board. I read around 150
> ohms to
> ground across that path, and considering the minor parallel
> resistance of
> the metering circuit, infer that the resistors are on the high side.
> Screen
> voltage on pin 6 of V3 is a bit high (195 versus the manual
> reference of
> 180).
>

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.asp?list=HEATH
To post - HEATH at LISTSERV.TEMPE.GOV
Archives - http://interactive.tempe.gov/archives/HEATH.html