Garey, that' sinteresting about the different slug colors. I seem to remember seeing reference to that and had completely forgotten about that.
With respect to setting the pointers, I have discovered, in my disassembly of these rigs, that if your pointer is "off" (on all bands) from where it should be that you can carefully move it on the shaft. The keyword is "carefully" - after all, the only way you'll get a replacement is from a donor rig! I've found that if I peak on 20CW, the pointer should be at the bottom of the "20" zone. I use 20m as the starting point only because it's somewhere in the middle of the preselector's range and the sensitivity of peaking adjustments are about midrange as well. Of course, if everything else is off, check elsewhere first. I always run the rigs through a quick evaluation before I start changing or replacing anything :) 73, Steve, W1ES/4 -----Original Message----- >From: Garey Barrell <k4...@mindspring.com> >Sent: Feb 13, 2012 5:03 PM >To: Steve Wedge <w1es1...@earthlink.net> >Cc: drakelist@zerobeat.net >Subject: Re: [Drakelist] R4B preselector alignment > >Steve - > >One exception. The R-4 had different slug heights, and a different alignment >procedure. Other than >that, all slugs should be at the same height. There is no reason for the >relationship to change >over time, so as long as the glyptol is unbroken, leave 'em alone. > >The other situation is the slug height specified for the various 'colors' >described in the T-4XC >manuals. Over time, the length of the slugs received from the manufacturer >changed, shifting where >they were in the coil in relation to the top of the form. They were color >coded with paint on top >of the slugs, around the spring shaft. I don't know what percentage of each >'color' (length) were >used, but I've seen very few with color dots. Again, you should just run the >RF TUNE to maximum >clockwise and check the measurement from the top of the coil to the top of the >coil form. If it is >one of the three measurements in the manual, leave the slugs alone and align >to the appropriate >dimensions for that color. Essentially, the trick is to have the RF TUNE >control cover the entire >range from 1.8 to 30 MHz, and have the pointer to be somewhere in the selected >BAND segment of the >dial. If your unit won't cover the entire range, then you might want to try >starting with another >'colors' dimension. > >73, Garey - K4OAH >Glen Allen, VA > >Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line >and TR-4/C Service Supplement CDs ><www.k4oah.com> > > >Steve Wedge wrote: >> I've found the same thing with respect to using the detuning resistor - it >> hasn't really made anything easier or more accurate for me. I suppose, when >> they were building and testing these sets that it shaved a few minutes off >> the technician's test time - which is significant for production testing >> but less so when you're the owner. >> >> The other thing I learned long ago - after speaking with a Drake tech on the >> phone probably 25 years ago - was that the absolute height of the slugs is >> less important (as Garey mentioned) and there should almost NEVER be any >> reason to change the individual slug heights in the rack. If nobody has >> messed with them over the years, they should all be in the same positions >> they were in when the set left the factory. I find the easiest way to see >> if someone has been "fiddling" is to adjust the preselector so that all the >> front slug is level with the cardboard tube top. All the other slugs should >> also be level with their tube tops. If you see a discrepancy, look to see >> if it looks like the glyptol (the substance that keeps them from moving) has >> been disturbed. >> >> Other than that, just peak them and be done. 80 is quite sharp and 10 is >> quite broad, with everything else somewhere in between. >> >> 73, >> >> Steve, W1ES/4 >> >> -----Original Message----- >>> From: Garey Barrell<k4...@mindspring.com> >>> Sent: Feb 13, 2012 2:30 PM >>> To: Peter Ravn<fas...@privat.dk> >>> Cc: drakelist@zerobeat.net >>> Subject: Re: [Drakelist] R4B preselector alignment >>> >>> Peter - >>> >>> The setting of the Passband tuner is not significant when doing the >>> Preselector alignment. All >>> you're looking for is an amplitude peak. Sometimes the Calibrator signal >>> is too strong, especially >>> on the low bands, driving the AVC too far and making it difficult to see >>> the peak as you tune. >>> Alternate Calibrator signals vary in strength, so you can pick a lower one >>> on either side (+/- 25 >>> kHz). You can also put a smaller resistor on the ANT jack to reduce the >>> level. Use FAST AVC to >>> better see the peak. >>> >>> The resistive loads are to spoil the Q of either T3 and T4 while tuning the >>> other to minimize >>> interaction of the adjustments. I have found that it really isn't >>> necessary, that you can do just >>> as good an alignment by going through 3-4 iterations of the adjustments >>> without the loads, as the >>> interaction refines out. >>> >>> 73, Garey - K4OAH >>> Glen Allen, VA >>> >>> Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line >>> and TR-4/C Service Supplement CDs >>> <www.k4oah.com> >>> >>> >>> Peter Ravn wrote: >>>> The otherwise comprehensive R4B preselector alignment instruction does not >>>> mention the position of >>>> the passband selector during alignment. Should it be in the same position >>>> as during passband tuner >>>> alignment, i.e. with the passband selector to .4, and the passband tuning >>>> knob to the shortest of >>>> the curved lines on the panel. Or does it matter at all? >>>> The manual suggests to use the S-meter when adjusting the preselector >>>> trimmers for maximum. I find >>>> it much better to use an VTM. Finally the idea of using alignment >>>> resistors on S5C and S5D escapes >>>> my understanding. >>>> Thanks >>>> OZ8CTH, Peter _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
