Trio 9R-59D - 9R-59DS

The Trio 9R-59D and 9R-59DS are two slightly different versions of the same communications receiver manufactured by Trio (later Kenwood) Electronics in Japan during the years 1969-1974. The receiver is an 8-tube single-conversion design (455 kHz IF), covering from 0.55 to 30 MHz in four bands, and featuring a calibrated electrical bandspread for the ham bands. The receiver provided an excellent value for its cost (105 $ in 1971), since it had good selectivity (ceramic IF filter) and stability and included a product detector for SSB reception. For those reasons it became very popular especially with SWLs in Europe and many good units are still available for sale, mainly in Germany.

I was not aware of the existence of the two different versions (maybe there is a third too, the 59DE), until when I purchased three of them on Ebay. It turned out that two were 9R-59D and one was a 9R-59DS. The only difference I could spot was a different front panel decoration (see pictures), more elaborate on the D, with a molded rectangular frame around the tuning dials and the S-meter. I believe that the 59DS is a more recent version. On the other hand the internals look exactly the same. Both types are equipped with SO-239 (UHF) antenna connectors.

This receiver is of more modern desing than the predecessors like the Lafayette HA-230 and HE-30 (which was in fact also known as Trio 9R-59 outside USA). It uses two printed boards (IF and AF stages) and there are silicon rectifiers in the power supply. It is probably equivalent to the Lafayette HA-700, except for the different dial arrangement (slide-rule type in the HA-700) and the use of different tubes.

The 9R-59D(DS) has a RF stage, S-meter, ceramic IF filter, tunable BFO and product detector. The stability is good and SSB reception is OK, much better than on the HA-230. The versions found in Europe are wired for 220 V power, so one does not need any external transformer.

Two additional nice features: there is an already wired socket where one can plug a OA2 regulator to stabilize the HF and BFO oscillators; and the chassis is pre-punched for crystal and tube sockets if one wants to build a calibrator. Also, I used the spare half of V3 as a cathode follower to feed the HF oscillator to an external frequency counter (useful since the readout is very poor). See here for the schematics.

The three units I purchased were all working. I had to replace the feet on two of them because they had suffered from some rough usage and improper packaging when shipped. The best-looking of the three is the 59DS.

Alignment history (all units):

• March 2006
• November 2006

9R-59DS Operating Manual (BAMA site)

		The 9R-59D logo. Notice the more elaborate framing of the tuning dial w.r.t. the 59DS.
		The 9R-59DS logo
		The 59D main tuning dial with the A,B,C,D bands.
		The bandspread dial is calibrated with the 80 m, 40 m, 20 m, 15 m and 10 m amateur bands and with a 0-100 logging scale.
		The function switch knob
		The band selector knob
		View of the chassis. The two printed circuit boards are celarly visible. On the rear apron, from the right: fuse holder; audio output terminal strip; multipin socket/plug for remote control when used with a transmitter; SO-239 antenna connector and antenna binding posts (balanced and unbalanced); S-Meter zero adjust.
		Bottom view of the chassis. The coil pack and the band switch are in the middle, with the mica trimmers well visible. On the upper left is the main power transformer. The two printed circuit boards contain the IF amplifier (bottom) and detector/BFO/AF section (left). The RF, oscillator and converter tubes are installed directly on the chassis.
		Detail of the 3-gang main tuning capacitor. The empty socket is already wired to accomodate a OA2 150 V regulator tube. A crystal calibrator can be built using the nearby holes for tube and crystal sockets.

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