The service manual states that you can jump into the alignment at any point if you are confident that all of the adjustments preceding that point are correct, but that the subsequent adjustments should all be performed in order through the end to ensure proper operation. It may be that only the 40 MHz (section 3-3 of the service manual) needs to be adjusted as Joe says, but at a minimum, I would suggest the OP also check the +10V adjustment (section 3-1) to ensure that it is where it is supposed to be. Don't adjust it if it's close, otherwise you are committed to the rest. The 10V adjustment affects everything.
I usually do 3-1 through 3-6. Then if the radio isn't in bad shape, I will just check 3-12 and 3-16 (and 3-15 if it seems justified) after that. If a frequency alignment is all that's necessary, just 3-1 through 3-6 is sufficient. Due to the ease with which the trimpots on the PS board in the front can be bumped out of adjustment, IMO it is good practice to at least check 3-6 whenever the cover is removed from the radio for any reason. Although frequency alignment does require a fine touch, it isn't all that difficult if you have a sensitive and accurate frequency counter and are handy with tools. The pots in 3-6 can even be set "close enough for government work" without a frequency counter by following a published Drake tech note that can be found several places on the web. Free service manuals can also be found on the web, and some nice reprints are available from online vendors if you don't have one. 73 -Jim NU0C On Sun, 23 Dec 2012 20:28:43 -0500, Joe Pyles wrote: >Adjust L1001 on the PBT/Reference board to put the 40 mhz oscillator >back on frequency. The 40 Mhz oscillator provides >the 500 khz reference for the DR7 board. the 40 mhz crystal tends to >drift more than the other two crystals on the PBT/Reference board. > >73, Joe KC9LAD > >At 05:37 PM 12/23/2012, you wrote: >>My TR-7 digital readout is off by 100 hz. Can anyone tell me how to >>correct it? >> >>I appreciate any and all help. >> >>James Wilson >>N5DBS > > -- The universe we're in will reach absolute zero in three hours. Safe is relative. - Idris, "The Doctor's Wife" _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
