Does anyone have the Hickok 288X schematic, at alteration level A? BAMA has level B, and the paper one I have is level nothing (all this is specified in the upper right-hand corner of the schematic, by the way). With Hickok's revise-as-you-go production, the 288X's I have are both somewhere between the schematic at no revisions and the one at the "B" revision level. By the way, Hickok's notes in the bottom middle of the schematics that detail what changed between alterations are far from complete.<P>------------------<BR>

I have a 288X. Lemme look for my docs. Packed away since move to new house. Weekend is perfect time to poke around in the un-marked boxes in my "radio corner." <IMG SRC="http://antiqueradios.com/forums/smile.gif"> Will advise.<P>------------------<BR>Chuck Schwark<BR><B><I>The Philco Repair Bench</I></B><BR><A HREF="http://www.philcorepairbench.com" TARGET=_blank>http://www.philcorepairbench.com</A>

Gee, what took me so long, eh? <IMG SRC="http://antiqueradios.com/forums/wink.gif"><P>Got lucky, it was on top in the first box I opened.<P>The title block on the schematic says: Dwg No. 617W, Date 5-23-47. Top right title block says: Alteration K and J. Looks like my schematic is a lot "newer' than your set then. <IMG SRC="http://antiqueradios.com/forums/frown.gif"> Sorry, maybe someone else will come through....<BR> <BR>At least now I know where all my bench test equipment manuals are...<P>------------------<BR>Chuck Schwark<BR><B><I>The Philco Repair Bench</I></B><BR><A HREF="http://www.philcorepairbench.com" TARGET=_blank>http://www.philcorepairbench.com</A>

Hi Chuck,<P>It's interesting that the revisions went that far. Maybe I'm completely wrong, since they never changed the date (the original version shows the same date). Maybe what I'm looking at is a post-B unit instead of a pre-B, like I'd assumed. It's hard to tell. Any schematic that's different from the BAMA version will help.<P>------------------<BR>

Sorry Erik, mine's a level nothing like yours <IMG SRC="http://antiqueradios.com/forums/frown.gif"><P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>

Assuming normal drafting methods, that 1947 date in the main title block (lower right) is the date of first drafting. Normally, revisions are dated as well as noted as A, B, C, etc. Too bad the revs are not documented as to changes either electronic or mechanical.<P>I'll scan and PDf my schematic and email it to you Erik.<P>------------------<BR>Chuck Schwark<BR><B><I>The Philco Repair Bench</I></B><BR><A HREF="http://www.philcorepairbench.com" TARGET=_blank>http://www.philcorepairbench.com</A>

I should describe my 288X, just to be sure my own cluelessness on the schematic revision level doesn't create confusion. I have no idea what revision level it is, or what date it was manufactured. It isn't a 288XA though, like you have Leigh . That's one of the solid few conclusions I have drawn about it. (I have three, and I'll leave the others for another day.) <P>The one in question has a 6SN7 for V3, and a mystery 1.5K resistor between pin 5 of V2 and T1. <P>------------------<BR>

Hi Erik,<P>There's no way a 6SN7 is going to work as a sub for a 6K8 <IMG SRC="http://antiqueradios.com/forums/eek.gif"><P>Check the socket connections for V3 against the schematic. If they match, you have the wrong tube in that socket.<P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>

Hi Leigh,<P>Hickok changed the game dramatically between the original design and even the "B" schematic revision, including a change from the original 6K8 to a 6SN7 for V3 (with the attendant component and wiring revisions). Part of the reason I resorted to this request is that my V3 connections, while approximating a revised schematic's connections for the 6SN7 tube, are reversed on some elements of the dual triode, and on for others, with the added clarification of being completely unlike the connections used for the 6K8 models. <P>The mystery 1.5K resistor is what drove me to post this request, since its presence makes no sense, and it doesn't show on any schematic I can lay my hands on. <P>------------------<BR>

<P>I have to think this is a 60-cycle source for the sweep function. The <B>Sync Sweep Voltage</B> panel jack derives its signal from one side of the HV winding through a 470K resistor, but that signal goes nowhere else.<P>The sweep must use a phase-synchronized voltage to perform its function. It may have been derived originally from the filament line, but changed to the HV line for some reason.<P>BTW, this is a real early schematic for the 288X, dated 1/2/46. I have two manuals, one for the X and one for the XA, and grabbed the wrong one <IMG SRC="http://antiqueradios.com/forums/redface.gif"> so let me see if I can find the right one.<P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>

Hi Erik,<P>I found the manual on the 288AX (the XA designation does appear occasionally in the text). It does have the 6SN7 at V-3, but no mention of the 1.5K resistor. The 60-cycle sweep voltage is derived from the 6.3-volt filament line through a 22K resistor.<P>This is a rev D schematic, but with a whole different number (902-419W) undated. It's on B-size (11" x 17") paper, completely redrawn, and actually legible <IMG SRC="http://antiqueradios.com/forums/eek.gif"><P>------------------<BR>73 de Leigh W3NLB | | Leigh@AtwaterKent.Info<BR><A HREF="http://www.AtwaterKent.info" TARGET=_blank>http://www.AtwaterKent.info</A> | | <A HREF="http://www.Synchrophase.info" TARGET=_blank>http://www.Synchrophase.info</A>

Erik<P>On the schematic with the 6SN7 for V-3 it shows a 33K from pin 5 of V-2 to T-1<P>Dave<P>------------------<BR>Intelligence is the ability to use your knowledge

<P>The plot thickens. The J K revision schematic Chuck sent me shows a 47K, with a slight wiring difference.<P>Thanks to all for the information. It sounds like I have something from an intermediate production stage, and my best bet is to replace with the same values I found. I can only guess what I'll find in the other two 288X's.<P>------------------<BR>

As Erik sez, The Thick Plottens......<P>Just found an original 288X manual I forgot I had. It's dated Jan 2, 1946 Part number 617W Upper right cover show <I>no</I> alteration letters.<P>Does this help or muddy the waters again?<BR> <IMG SRC="http://antiqueradios.com/forums/smile.gif"><P>------------------<BR>Chuck Schwark<BR><B><I>The Philco Repair Bench</I></B><BR><A HREF="http://www.philcorepairbench.com" TARGET=_blank>http://www.philcorepairbench.com</A>

Hi Chuck,<P>Thanks, but I actually have that, in paper form. It was a reprint, and doesn't match my 288X entirely. In looking at that, the "B" revision that BAMA has, and the "K" that you E-mailed me, I think I'm somewhere between "C" and "I." I noticed another tube type change had occurred by the "K" revision versus what I have. Today I found a couple more mystery resistors that don't match any schematic I've seen yet. <P>------------------<BR>

Hi All,<P>I have the manual for 288X, alteration "A", but there is no mention of a 1.5K resistor from V2 to T1. Alteration "A" is dated 11-19-46, and adds R31 (1.8K) from V2 pin 3 cathode to ground. The schematic in this manual has V3 as a 6K8, but there is a revision page showing the 6SN7 alternate circuit for V3. <P>I also have the schematic for 288AX drawing number 999W dated 10-18-61, no alternate number. This shows a 47K resistor from pin 5 of V2 to T1.<P>The 288AX I have has been heavily modified by the former owner, with some solid state components partially installed and lots of pencil notations on the schematic. I purchased the 288AX as a standby generator in case the HP 606A on the bench goes down (not likely).<P>I don't have a scanner, but I would be glad to copy and mail all or part of the Hickok manuals to anyone who needs them.<BR><P>------------------<BR>Meade

Alteration C, dated 5/23/47, has the 1.5K resistor, the B+ feed for V2. Drop me an email reminder and I'll mail you a xerox.<P>------------------<BR>

Perhaps everyone could post the schematics they have in the photo gallery (temporary). That way we could get all the schematics together and I could post them in Bama.<P>Or you could just e-mail them to me if that would be easier. It would be nice to get these on Bama.<P>Dave<P>------------------<BR>Intelligence is the ability to use your knowledge

Great idea. I'll send you everything I have when I get the mailed material in hand.<P>------------------<BR>

I'm making two xeroxes of as many manual pages as I can get away with, here at work, and will send copies to each of you if I have mailing addresses (I know they're buried in old emails somewhere but it takes a while to find the right ones).<P>If I scan them the files will be big jpgs as that's all I know how to do with the old program I use. Best to mail the xeroxes and let you scan in whatever format you want.<P>------------------<BR>