T-4XC question

[WQ9E]

I just finished going through a recently acquired Drake C line and I used it to make a few CW contacts earlier today.  The R-4C, T-4XC, MS-4, AC-4, and MN-4 were at a great price of $250 and included the CW filters for the R-4C (late model with the 3 CW filter positions), the noise blanker, a lot of extra range crystals, a D-104; CW key, and 3 spare sets of Sylvania finals.  The only issue I ran into was problems with the xtal oscillator on the T-4XC and the problem is that the crystal select decks of the switch are driven by a right angle drive off of the main bandswitch shaft and in this model Drake used Nylon gears for the right angle drive.  The gears do not appear worn and they are not cracked but there is enough slack in the drive system that the alignment of the spur shaft is very critical in order to make the oscillator work.  Apparently Drake was aware of possible issues because the contacts on the rotors of the crystal decks are much wider than normal and the problem in mine was that when going clockwise the rotor would sometimes stop in contact with two positions simultaneously.

Has anyone been inside their T-4XB recently (or maybe an earlier production T-4XC since this one is in the 28,000 range) to see if the earlier models used metal gears?  WRL used a similar switch setup on the Galaxy V but in their case the right angle drive is metal and is securely anchored to the chassis as opposed to the floating unit in my T-4XC.  I have some earlier Drake units but it has been awhile since I have been inside one and I am lazy enough I wanted to avoid pulling the cabling and taking the unit apart just to satisfy my curiosity if someone else has been inside an earlier model T-4X recently.

The setup had one other interesting issue and that was with one of the interconnect cables.  The C line phase locks the carrier oscillators in the receiver and transmitter together unlike the earlier units in the series.  The original Drake cable had a poor connection at one end and instead of a single phase locked signal I had two slightly offset carrier oscillator signals which made the calibrator and other signals sound rather interesting on the receiver.

Rodger WQ9E

[W2JBL]

i have a T4XB from about 1972 and it has plastic gears. it's allways given me those bandswitch problems. if the 90 degree coupler was better supported and the shafts had real bearings it would help but i never messed with it, as the only band i use the aux crystals on is 160, and lately i only use it on that band so i never disturb the bandswitch. it's a great low power transmitter AM with a few simple mods. short out the silly grid leak resistor in the PA, regulate the bias and kill the ALC and it even puts out a fairly clean SSB signal too.

[WQ9E]

Thank you for the info!  This is the first T-4 to cause problems for me and I have all 4 sets of twins from the original 4 line through the C line.  Hopefully my adjustment will hold or otherwise I may do some mechanical modification to improve the rigidity of the setup.   I used to use a C line for contesting back in the '70's and I am surprised with all of the band changing I did I never found the problem.  It was often operated in split mode for DXing so the issue should have shown up but maybe even though no wear is readily apparent 30+ years of time are starting to take their toll on some of the mechanical parts.