FTdx400 SSB Transceiver

from Sep.16,2000 counter

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History of Yaesu "400"

The FTdx400 is the very initial model of the Yaesu famous series of "401", which is roughly divided into three types.

    (1)Initial model FTdx400
    (3)Finish model FTdx401/dx570/401B

The FTdx400 was all the starts, while FTdx401/dx570/401B were the finish edition of the series, and I would say FTdx560 was a product at a transition period. There were a lot of editions as the 400 series, but in common, all of them were tube-based equipment and had powerful 200 watt output. From late 60's to 70's, all of them made their own period as one of the most typical SSB transceivers.
It's easy to wrap up their features under just two or three lines, but who knows the features and differences clear as old timers. For such English readers who would like to know a positioning of the entire 400 series and its features, I will provide this page from their mother country. Please take a look at below, you may have a knowledge of 400 seires as Japanese old timers do !

Here is a complete list of all related models:

Click link to see a catalog.

Model Sale on Price in Japan [Yen] Price in US [USD]
FTdx400 October,1967 118,000
FLdx2000 October,1967 46,500
FLdx400 November,1967 79,000
FRdx400 November,1967 62,800
SPdx400 November,1967 2,950
FTV650 June,1968 29,500 $194 (1975 catalog price)
FVdx400 April,1969 18,500
FT400S May,1969 89,000
FL2000B September,1969 79,800 $359 (1975 catalog price)
FV400S January,1970 19,500
SP400 January,1970 4.300
FTdx560 January,1970 $450 (1971. Q3 sale price)
FL2500 February,1971 63,000
FTdx401 May, 971 128,500
FV401 June,1971 19,500 $99 (1975 catalog price)
SP401P August, 1971 $59 (1975 catalog price)
FT401S September,1971 95,500
FT401D September,1971 99,800
FTdx570 Unknown $550 (1972. Q3 sale price)
FT401B Unknown $599 (1975 catalog price)

First of all, let me introduce two entry models of the 400 series named FT-400S and FT-401S, that were only available in Japan. Probably you may know the name of them, but what is the difference of these models and FTdx400/401/560/570....?
FT-400S was a 10 watts version of the FTdx560. Though she was often misunderstood as a low power model of FTdx400, it was completely a different model. Other than the power, I would say FTdx560 and FT-400S were completly the same gears. On the other hand, FT-401S is(was) a 10 watts model of FTdx401 and FTdx570, with single 6JS6 tube for final power amplifier instead of two of 6KD6s. As FTdx560 was improved to equip a fan and a noise blanker to be the FTdx570, FT-401S had also been improved by adding such new features to FT-400S.
One more model was a FT-401D, that had 100 watt output with two of 6JS6 tubes; say mid brother of the FT-401S and FTdx401. There was a modification kit for FT-401S available at Japanese market to make the 401S 100 watts output possilbe, same as FT-401D, that contained one 6JS6 and its socket, that makes parallel 6JS6s possible, and capacitor for rectifier circuit for 600V Ep.
There was an another model named FT-401B which looks similar to the FT-401S and FT-401D. But FT-401B was a 200 watts model, an improved model of FTdx401/570 to be equipped with an AM mode and a CB band, and had brushed up face, that was only available in US. FT-401B was the very finish model of 400 series as well.

There were some related models of FTdx400, "The YAESU twins", FLdx400 for the transmitter and FRdx400 for the receiver. I believe this must be a good hint for twins owners who wish to repair her perfomance better, though Japanese subscription. In addition, there were some linear amplifiers as FLdx2000, FL2000B, and FL2500, as well as matching VFO's, speakers and a transverter FTV650, etc.

Also there were some related models in Europe under SOMMERKAMP brand, such as FTdx500, FTdx505 and FTdx575. I'm not sure at present but FTdx500 was a sister model of FTdx400, FTdx747 was of FTdx560, and FTdx505 seems to have been a sister model of FTdx401/570. Related information from any Europian readers would be appreciated.

The following page may provide you more informations in detail....

Virtual Museum of YAESU 401

Sorry for the Japanese language, but I believe you can use some internet translation webs as well. Or please enjoy many pictures at the page.

MY COLLECTION as a part of the MUSEUM


What's FTdx400

The FTdx400 was one of the flagship models of YAESU MUSEN Co., that was designed to provide the best performance for variety of user demands by means of tube that was the most stable electronic device at that era.
In terms of SSB transceiver that consisted of tubes, FTdx400 was similar to the Heathkit SB-401 and Collins KWM-1/KWM-2 in general. However, because Yaesu had very challengive models of FT-100/ FTdx100, the positioning of another FTdx400 at Yaesu had been a bit different from Heath and Collins. Since FT100/FTdx100 consisted of transistors mostly (except for power amplifier), kind of mother model of well known FT-101, and therefore that can be used comfortably at field operation with built-in DC-DC converter, FTdx400 was mainly focusing on its performance and usage as base station.
If only FTdx400 was set upon an operation desk, running 400W high power operation had easily been possible. Not only the high power operation, but also the FTdx400 had all the power supply installed as well as many accessory circuits such as frequency calibrator, VOX, high accurate and stable VFO, clearifier and break-in for CW operation; one of the highest cost performance equipments for radio amateur.

It was on the market on Oct.,1967, catalog price was 118,000YEN in Japan. Since freshman's salary of that time was 30,000YEN to 40,000YEN in Japan, the FTdx400 was just coincide to FT1000MP MarkV now.
Also difference was in exchange rate between USD and Japanese Yen, which was greatly different from now (USD$1 = 360 Yen at that time. Currently USD$1 = 100 Yen ), trade situation might be very much advantageous to Japan.

Here is a picture from ad. on May 1967's ham radio magazine, which I guess was a prototype of the FTdx400. It looks very much similar to FTdx100.

Many thanks to JA7UQ

As all of old timers know well, the FTdx400 had many versions in its model. According to my investigation, there were five or six versions of model in FTdx400.
I have ever seen from second to fifth version of the Ftdx400 at US eBay auction, but never saw first version in US. On the contrary, there are so many auctioned items of the first through fourth version in Japan, but not for fifth version.

(1)Very first model of the FTdx400

    When the FTdx400 was on the market on October,1967, it was:

      --with beautiful silver face, gray cabinet and silver metal legs.
      --2x 6KD6 for final tube that allow to run 400 watts operation.
      --Hybrid stable VFO allows us to read out 1 KC(not KHz !) correctly.
      --AM operation possible
      --There are no four slide switches at front face.
        Some switchs at an outside of a double axis knob were allocated for switchs of substitution of the slide switchs of FTdx560 etc.

    Also the features of this very first model of the FTdx400, that were fairly big differences from well known FT401/570(the latest model), were as follows:

    --Use big power transformer: muuuuch more lager than FTdx560/570's.

      The transformer had a cupper band for magnetic flax shield.

    --All rheostats were placed at a side panell of the final cage.
    --VFO was oscillated from 8.4M to 8.9M usinng 2SC372 bipolar transistor.
    --50K/turn dial with adjustable knob for rotation smoothness
    --Simple VFO finction selection was only provided. EXT VFO was working for only transmission.
    --Driver tube using was 5763
    --No CW filter was applied.
    --No Fan (did not adhere)
    --Frequency verniar for the transmission was installed as well as clearifier for receiving.
    --Even low voltage surply for transisters was from VR105MT.
    --First IF transformer was NOT a BPF but tuuned with variable capacitor at VFO section.

    Also please take a look at this page. This is a page for my restoring memory when I got this first version of FTdx400 on June 2002. You will find a lot of pictures inside a cabnet.

(2)SECOND EDITION --First big change of the face (around December 1968)

    --Driver tube was improved to 6GK6
    --Tuning dial was changed to double rate cooaxial style knob in order to make it same looks as the FVdx400.
    --ACC connecter was changed from 9 pin to 11 pin. That makes it easy to hook up the FTV650(June 1968) onto FTdx400.
    --VFO selector switch was changed by which cross operation using EXT VFO had been possible.


    --Transformer was changed to smaller one; same size one as FTdx560/570's.
    --All rheostats were moved to back panel.
    --Power surply for VFO was from Cathode of the 6BM8.

    Since the face was completly the same as previous one, this modification might be for rather cost down issues than improvement.

(4)FOURS EDITION --Modification towards the third face and fundamental circuit improvement

    (later than serial number of 9062241(on the market after June 20th 1969 in JA))
    --Main tuning knob was changed from double rate coaxial dial to 25KHz/turn dial.
    --Also VFO circuite had been chaged to FET circite instead bipolar transister.
    --Silicon diode for high voltage rectifire had been chaged to 10D10.
    --First IF transformer was changed to BPF.
    --Crystal filter was changed from XF3 to XF3A. CW filter (XF3C) can be installed as option. See internal structure of XF-3(bottom) and XF31A(upper). Both filter was using 6x HC6U X'tal unit.
    --Power output for CW mode had been able to be adjustable by a rheostat placed at main PWB.

    >>>There was a miner change edition of this version that was around June 1970 that changed a VFO frequency to 8.9M - 9.4M, using FET. This range of the VFO frequency had been the basis of later all items of Yaesu equipment including FT101.
(5)FINAL EDITION of the FTdx400

    --Changed to 100KHz/turn dial; same as FTdx560/570's.

    This fifth version was a base model to be the FTdx560. Basically, there were no change circuitry other than a rejection of AM mode and change in their view.


LINK to AA4VI's YAESU FTdx560/570/401/400 Web Page

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