WaHoo ! That was it, C159 was way leaky, and my version does not have R142, so that added some confusion.
S-meter's working great and receiver's hotter than I can recall in recent memory ! As always, thanks Garey, Chuck, K1OM On Feb 16, 2008 11:13 AM, Garey Barrell <[EMAIL PROTECTED]> wrote: > > Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist > gang > ---------------------------------------------------------------------- > Chuck - > > I was just typing my last as you were sending yours... Great minds, > etc. :-) > > Nothing like having the right schematic..... C159 is a 0.01 disc > ceramic in this version. > > R142 likely has gone way up in value or cracked. Not in the earlier > schematic I was looking at. > > Schematic in separate message off reflector. > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs > <www.k4oah.com> > > > > Chuck Grandgent wrote: > > 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 > > > > > > > > > > > > > > > > > > > ---------------------------------------------------------------------- > Submissions: [EMAIL PROTECTED] > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ---------------------------------------------------------------------- >
