Anybody know the difference, besides different VFO knobs, between these two animals?
I just picked-up a T-4X on a whim because it was cheap, to go with the R-4B thats still on the way.
I thought I read somewhere on the internet that the T-4X is not as "clean" on SSB do to the sideband generation method compared to the B and C models. That is the one and only time I heard anything negative about the plain X model.
I'm aware that Drake was smart making sure all three versions of the "twins" were backwards compatible with each other.

Not sure. I ran a T4-X with an R4-B for about 8 years and was always happy with it. That was before the internet, though

Here is a useful Drake page: http://www.wb4hfn.com/DRAKE/DrakePageHome.htm

Sideband generation has always been filter type in the Drake T-4 series with separate filters for each sideband and the audio is very similar across all T-4 generations. The receiver didn't receive crystal filtering until the R-4C although there were some modification articles for using the transmitter filters early generation receivers to improve skirt selectivity.

Although not a perfect cosmetic match the T-4X will work fine electrically with the R-4B (or any of the R-4 series). With the C line gear, the carrier oscillators were locked together if you used both the C line transmitter and receiver but with earlier gear (or a C unit used with an earlier rig) there is a simple adjustment to make sure that the receiver and transmitter are properly frequency matched. Drake specifies alignment loads when aligning the transmitter and receiver pre-mixer/antenna/driver sections but over the years I have had better results doing the alignment with the receiver and transmitter cabled together so that you are doing alignment with the real world circuit loading in place. Note that a couple of the interconnecting cables between receiver and transmitter should be low capacity types.

Unless you know that the power supply is newly recapped at least replace the bias filter capacitor. A failure of this cap will cook the final tubes even if the transmitter is sitting in standby. A cooling fan for the finals (either blowing air through the back or sucking air through the top over the finals) is a very good idea. Sweep tubes are no longer cheap and a little cooling air will increase their lifespan. It is also very important with sweep tube finals to load the transmitter properly to rated output. You can increase the lifespan of the tubes by reducing the power but this should be done so by reducing drive to a properly loaded final and not loading light. Light loading causes excessive screen grid current and this will quickly damage the tube. Sylvania brand 6JB6 tubes were preferred but most brands will neutralize OK in the Drake. I am using 6GJ5 tubes in my T-4X and they neutralize and seem to work fine although output may be a little less on 10 meters. This may just be the particular tubes I used and not the difference in GJ versus JB tubes. 6GJ5 tubes are much cheaper than 6JB6 tubes now if you have to find a pair.

Rodger WQ9E

Thanks everyone.
Well the T-4X arrived, I bought it from a fellow Ham on Ebay. He described it honestly saying that it has full output on 20M and no output on the other bands. He lost interest in it and does not have signal generator to attempt the alignment procedure.
Could this be an alignment issue?
Except for looking like it sat unused for a long time, it appears original and unmodified. I don't have a power supply for it so I can't do any testing right now.

No output on other bands sounds like either a problem in the crystal oscillator or a problem with a switch. Cycle both the front panel crystals switch and the band switch several times. Poor alignment would likely cause much lower output on some bands but it is unlikely it would drop to zero. Are you sure the output on 20 meters is actually on the correct frequency or is the transmitter loaded up on a spurious signal?

If the PTO is operating it can be detected in a receiver, it operates between 4.955 and 5.455 Mhz. depending upon the PTO dial setting. The premix crystal oscillator operates at 11.1 Mhz. above the lower band frequency (i.e. 14.6 on 80 meter band setting) and it can also be heard in a nearby external receiver.

If cycling the switches does not help then try cabling it to your R-4B and then run transceive from the receiver and see if it now has output on the other bands. This will help you to narrow down the problem.

Rodger WQ9E

Drakes are prone to crystal problems as well as corroded sockets/pins. Also a weak tube and dirty switch problems could be at fault. Be sure the PS is putting out correct voltages.

Carl

When you say "crystal problems" what exactly do you mean? The crystals them selves or the pins/jacks they plug into?

The crystals were probably from the cheapest source they could find and they are now failing to oscillate usually due to contamination from assembly.
The sockets and pins can be cleaned but the crystal can is soldered to the base and it takes some skill to get apart, clean the crystal and holder and get it together again. New crystals run $20 and up.

Carl