C159 was definitely bad Garey, replaced that and now I have S-meter
action.
However I still have no plate voltage on V5, and for the life of me I
can't see how it's wired for it. It seems to have a 22k resistor
across T10 on the V5 plate side, and other than that and the
connection to C159, I don't see how it gets to any voltage, it's like
R142 is missing.
My serial number is 6987.
Chuck, K1OM
On Feb 15, 2008 11:30 PM, Garey Barrell <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Garey Barrell <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
made an utterance to the drakelist gang
----------------------------------------------------------------------
Chuck -
C159 may be very leaky or shorted. 0.1 uF at 200V. You may have a
fault in T10. B+ is applied to V5 through the primary of T10 and one
end of the secondary is at ground. Check DC voltages on either
side of
T10. A plate-suppressor grid short in V5 could have smoked T10,
so use
a known good tube.
The 6HS6 filament is just a filament wiring anomaly. According
to s/n
4054 schematic Pin 4 should be 6.3 and Pin 3 should be 0. What is the
s/n of your R-4A? I have the correct schematic.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com <http://www.k4oah.com>>
Chuck Grandgent wrote:
> The plot thickens.
> I checked resistance and voltage at all the pins for V2, V3, V4, V5.
> The two bads are:
> 1) V5 12BA6 pin 5 (plate), resistance is 150 ohms, s/b 10k. And
> votage is 3 volts, s/b 110v
> I guess R41 and maybe R142 bear more checking, though if either of
> these went high, I can't account for the low plate to ground
> resistance through this fault.
> Swapped this tube also with no effect.
>
> 2) V2 6HS6, manual says pin 3 (filament) s/b 6.3, is zero and
pin 4
> (filament) s/b 12.6, is 6.4. Looking at the schematic, not sure
what
> to make of that. And actually I did swap between my two 6HS6's with
> no difference.
>
> Chuck, K1OM
>
> On Feb 10, 2008 6:54 PM, Chuck Grandgent
<[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>> wrote:
>
> OK, got some time to spend on this today.
> R40, R41, R42, and R89 SEEMED to checkout OK.
> However, if I put a potentiometer across R41 and adjust it for a
> low value, I can get the S-meter to respond. Then, the S-meter
> zero adjustment R42 can bring the S-meter to any level on
the meter.
> But, it seems totally non-responsive to any received signal.
>
> I was also able to adjust the receiver sensitivity potentiometer
> on the bottom so TP2 was minus 1.35 volts.
>
> I replaced V4, V5, and V3, with no discernable difference. I
> didn't have a spare for V2 6HS6.
>
> What to check now ?
>
> Thanks, Chuck, K1OM
>
>
> On Feb 6, 2008 5:12 PM, Garey Barrell <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>>
wrote:
>
>
> Garey Barrell <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>> made an utterance to the
> drakelist gang
>
----------------------------------------------------------------------
> Chuck -
>
> OK. That's good!
>
> From your description, the AVC circuitry is working...
>
> I don't have a good photo, but I bet three of the four
> components are on
> the board with the S-Meter Sensitivity pot, next to the
> crystal. R40
> (1k Trim), R41 (820), R89 (560) and associated
connections. A
> series of
> ohmmeter checks should find it. I'm betting R40 is
open, or a
> broken
> wire/connection. :-)
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
> Drake 2-B, 4-B & C-Line Service Supplement CDs
> <www.k4oah.com <http://www.k4oah.com>
<http://www.k4oah.com>>
>
>
>
> Chuck Grandgent wrote:
> > Thanks Garey,
> >
> > well the meter seems OK, the DMM on lowest resistance
range
> causes it
> > to deflect a tad. I had to repair the AVC switch at one
> point, I
> > guess I should check there, among other places.
> >
> > Chuck, K1OM
> >
> > On Feb 6, 2008 4:20 PM, Garey Barrell
<[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
> > <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>>>
> wrote:
> >
> >
> > Garey Barrell <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
> <mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>>>
> > made an utterance to the drakelist gang
> >
>
----------------------------------------------------------------------
> > Chuck -
> >
> > The S-Meter is a simple bridge circuit that
compares the
> plate current
> > of V2 and V3 with the plate current of V4 and V5.
There
> are only two
> > resistors and two trim-pots! Since the radio seems to
> be working more
> > or less normally, those tubes are probably "good
> enough". If the
> > meter
> > needle is just sitting there on the mechanical zero
> point, it's most
> > likely an "open" in that circuitry. Just as a guess,
> I'd first check
> > the meter terminal connections, then wonder about the
> S-Meter
> > Sensitivity pot, but it could be a bad connection or
> (YIKES!) an open
> > meter movement. The movement itself is 3 mA, as
are ALL
> the R-4/T-4
> > meters, so can be checked with a DMM for continuity.
> Don't try to
> > use a
> > VOM, as they put too much current through the ohmmeter
> circuit.
> >
> > 73, Garey - K4OAH
> > Glen Allen, VA
> >
> > Drake 2-B, 4-B & C-Line Service Supplement CDs
> > <www.k4oah.com <http://www.k4oah.com>
<http://www.k4oah.com>
> <http://www.k4oah.com>>
> >
> >
> >
> > Chuck Grandgent wrote:
> > > R4A, S-meter was working OK, just noticed it is not
> right now, don't
> > > know for quite how long.
> > >
> > > AVC is working, as evidenced by turning RF gain all
> the way down and
> > > then back up, AVC slow takes very noticeably longer
> for the RF
> > leve to
> > > return once I turn up RF gain, compared to AVC fast.
> > >
> > > Adjusting R40 and R42 for S-meter and balance have
> zero effect,
> > > S-meter is all the way to the left.
> > >
> > > Things to try ?
> > >
> > > Tnx, Chuck, K1OM
> > >
> >
> >
