The Allied AX 190

Circa 1971 - 1975

    FEATURES:

The rear panel connectors are as follows, left to right:

1. 1/4" Speaker jack

2. Tape out

3. VFO out

4. Standby connector (jumpered)

5. AC / DC switch

6. 12 volt input (shielded plug inserted)

7. AC cord

8. Fuse holder (3AG)

9. HF out

10. Ground screw

11. Antenna,  SO-239 connector standard

This receiver came in two models.  The AX 190 was the "ham band" receiver and the SX 190 was the "shortwave" model.  The only difference (to my knowledge) is the band crystal frequencies, and the panel lettering.  Both have 11 band switch positions, and the VFO tunes "up" 500KHZ from the band start point, depending on the frequency of the crystal inserted in the corresponding internal crystal socket.  The preselector is a triple tuned RF section, in two ranges, 3 to 10 MHZ and 10 to 30 MHZ, as indicated on the preselector dial.  The literature claims the tuning range starts at 3.5 MHZ but it actually tunes down to 3 MHZ.  The bottom three band positions tune 3 to 10 MHZ, and the top 8 positions will tune 10 to 30 MHZ.  What happens is the band switch shunts in a coil in the upper band positions.  This can be modified to give more low band positions by cutting away part of the rotary switch contacts.

This radio was obviously designed for transceiver operation, since it has jacks for HF out (the band select crystal osc) and VFO out.  They even went to the expense of buffering these signals.  However the accessory transmitter box was never manufactured.  The VFO is quite stable, consisting of a separate shielded unit.  The tuning is very smooth.  It is made up of a brass gear train employing anti-backlash gears.  If you are not familiar with anti-backlash gears, let me describe.  Imagine a gear split in half like an Oreo cookie.  One of the gear halves is keyed to a common shaft.  The other gear half is free to float on the shaft.  One or two windows are cut through the sides of each half, and one end of each window has a notch to accommodate a compression spring.  When this gear assembly is engaged with a standard gear, the teeth of the anti-backlash gear are expanded to take out all of the slack and clearance, giving 100% meshing, the pressure being supplied by the springs.

An Anti-backlash gear, this one uses tension springs instead of compression springs

A cosmetic feature of the AX 190 is it's black out front dial cover.  It is a smoke black plastic, so when you turn the radio off, the preselector dial, main tuning dial and S-meter, seem to disappear.  This is fine and dandy for most situations, but if you want to operate the receiver on battery, the back light bulbs can use more power than you may want.  One of the mods is to put a switch in the bulb lines.  Another situation is if sunlight falls on the front, or it is used outdoors, it can be difficult to see the dial.  The radio is Japanese made, and has that Kenwood / Trio look about it, but they did not make it.  Original cost was $249, and marked ARS (Allied Radio Shack) with Tandy on the back.

The audio on this rig is a little whimpy, but communications grade.  If you want more robust sound, you can connect an external amp and speaker to the tape out jack.

This receiver had a bit of a following, and a 108 page PDF file of reviews, modifications, and manuals can be found here:

http://deane.bio.ucalgary.ca/Allied-SX-190-Info-Oct02.pdf

Internal photos can be seen here:

http://www.qsl.net/la5ki/org/al/ax190.htm

and eHam reviews, (it gets a 4 out of 5) can be read here:

http://www.eham.net/reviews/detail/1192

KG8YN