| AF9J |
Rating:     |
2014-03-08 | |
| A Nice Rig Back In The Day, and a Fun Rig Today! |
Time Owned: more than 12 months. |
Mine is the semi-rare FTdx-401B. They were only made for a year (1974-1975, the FT-401B [the last of the line], was introduced after this radio), and differ from the plain '401, in that they have AM transmit and receive capability. Unlike the earlier members of this product line (the 400, 560, and 570), they came stock with a cooling fan attached to the back panel, feeding into the finals cage (which is a nice touch - 6KD6s don't tolerate getting very hot, too well).
I got mine at a small hamfest in late 2011 for $140, from a guy who had not used it in at least 10 or 15 years. When he quit using it, he put it on a shelf in his basement, and there it sat. I was told that the finals were going soft, but that other than that, it mainly needed tweaking/re-alignment due to its age. I had passed on an FTdx-400 a I had picked up uber cheap at another hamfest, to a friend with limited funds (before I got it running - my friend is a retired RF Tech, and is bit by bit restoring that radio, as time and funds allow), the price was right for the '401B, and I wanted another FTdx, so I bought it.
The FTdx-401B turned out to be in a bit rougher shape than it was described to be. The radio was gunky and dirty on both the outside and inside (I think the seller was a smoker, and letting the radio sit in a cold, damp basement, didn't help things in the cleanliness department), and I had to spend a fair amount of time cleaning off all of the grunge. It also turned out, that the 6BZ6 IF amplifier for the receiver section was bad, and as a a result, it failed on power up (for the first time). Normally, this would have been nothing more than an annoyance (hey!, why is the receiver deaf!), but upon replacement of the tube, the '401B still wouldn't do much. My friend whom I'd given the FTdx-400 to, noticed on the schematics for both the '400, and the '401B, that there was a wiring error for the voltage regulator tube (for some strange reason, Yaesu ran voltage feeds to the same common votalge regulator tube input point, instead of one to the input, and one to the output of the voltage regulator). As a result, when the IF Amp. tube failed, it sent a voltage spike through the radio, that destroyed R48. So, I ended up re-wiring the feeds to the voltage regulator tube, and also replacing R48.
Once I did these things, receiver worked fine, the transmitter not so fine. The carrier wouldn't null out in SSB mode, necessitating the replacement of the 7360 tube, which is used for the balanced modulator (7360s have no substitute, and so I've stocked up on a few extras). The 6KD6 finals turned out to not be soft, but just plain shot! I picked up a pair of NOS Toshibas at a hamfest, neutralized them in the FTdx-401B, and I was good to go in late 2012.
What's it like to use? Well, like any sweep tube rig, don't go bonkers with key-down time, while tuning up. Sweeps don't take kindly to this, and and that definitely holds true for 6KD6s (oh yeah, I have to remember to get a spare set or two of these tubes as a "just in case" thing). Despite that warning, tune-up is quick and easy to do. Power output is anywhere from 250-300 watts. You could probably eke another 20 or 50 watts out, but it's not a good idea to do so (remember the finals are sweep tubes, that can do without the additional heat that pushing the tubes a bit more, would generate). My '401B doesn't have the CW filter, and I have other rigs that I prefer to use for CW. so I use mine for casual SSB operating (I haven't tried it on AM yet - I'm not sure if I will, since most sweep tubes don't take kindly to the extra heat that AM's higher duty cycle generates [although, the radio would probably do fine, if the power output is kept relatively low]). I get nice audio reports on SSB.
The receiver has nice audio, decent sensitivity for HF use, and has a low amount of internally generated noise, compared to some of my more modern radios. The inclusion of both a noise blanker, and 25 & 100 kHz marker generators/dial calibrators, are a nice touch, not always found in radios of this vintage.
In general, it's a nice radio. No, it won't keep up with today's latest and greatest top radios, and it would not be my first choice for contesting, but it more than holds it's own (in my opinion) with modern radios for casual operating. It's easy to operate (as long as you remember how to properly tune up a sweep tube final rig), and makes a nice conversation piece for ragchews. Despite the hassles I had with getting mine working right, it has become my favorite casual operating rig. The receive audio sounds great - it sounds warmer to me, than that it does for my solid state rigs. The extra power it puts out, (barefoot, compared to most modern rigs), has come in handy when conditions are bit less than optimum on the bands.
Like I said in the title - it's a fun rig to operate, that has become my preferred casual, "shoot the breeze on the air" rig.
73,
Ellen - AF9J
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| VK2KTZ |
Rating:   |
2002-02-24 | |
| Difficult to work on. |
Time Owned: 0 to 3 months. |
The Transceiver presents well, quite large, with good quality front panel and knobs, reduction plate tuning drive, and good feel from the VFO.
Marker generator has 100kHz and 25kHz.
The Transmitter follows "normal construction practice" and is quite robust, the receiver/modulator is on a LARGE printed circuit board, with tubes and transistors mixed together. The circuit diagram in the manual does not relate to the receiver very well, there are "daughter" boards everywhere, at right angles to the main circuit board, and are not discussed in the owners manual.
Build quality is generaly good, power voltage ranges from 100v to 234v 50/60Hz. Output is high, with 560W PEP input.
VFO is stable. Final cooling fan is noisey.
Clarifier is strange, in that all the way to the left is 'off', with centre being '0'.
Mine has an AGV fault (another part of the circuit that isn't in the manual) but I will track it down.
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