RETRO RECEIVER REVIEW #17
ALLIED / REALISTIC SX-190
by CRAIG SEAGER VK2HBT
Allied Radio was a U.S. company founded in the 1920s, ostensibly to distribute spare parts for Columbia Radio Corporation, but later branching into general electronic components. It fulfilled several government contracts during World War 2, later returning to consumer electronics and publishing a regular catalogue that was pawed over by many a young hobbyist.
For lots of enthusiasts of my acquaintance, this was their golden age of radio.
Allied also released some receivers under its own badge, all built in Japan, including the well regarded SX-190 of 1971-73. Later production bore the “Realistic” moniker, Allied having been swallowed up by one of its competitors, Tandy Corporation, in 1970.
The Allied/Realistic SX-190 was a general coverage solid-state set. However, coverage was restricted to the main shortwave and broadcast and amateur bands, with crystals supplied for 80, 49, 40, 31, 25, 20, 19, 16 and 11 metres. Two extra crystal slots are provided for additional bands with a 500 kHz bandwidth. A variant, the AX-190, is almost identical except that it covers the ham bands only.
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| The SX-190 bank of crystals |
A superheterodyne design, the SX-190 has its first IF at 2420-2920 kHz, and the second at the conventional 455 kHz. The circuitry consists of 4 FETS (all 2SK19, also featured in many other popular enthusiast receivers of the era), 22 transistors and 2 Zener regulators.
For those who like to “peak and tweak”, there are plenty of controls on the sexy looking front panel. A Q-multiplier rejects heterodynes and other adjacent channel crud, whilst a well-designed preselector with separate tuning dial is used to optimise sensitivity for each frequency range. A large central knob controls tuning, with reasonable accuracy possible from the bandspread dial; twin crystal calibrator circuitry injects tones at 25 and 100 kHz when engaged.
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| An aerial view with the lid off! |
A crystal-controlled BFO resolves LSB and USB signals, and a switchable ANL circuit is furnished for the AM mode. Speaker and headphone connections are provided, as well as both HFO and VFO outputs. The matching speaker (SP-190) is a separate unit, and there are connections on the rear for operation in conjunction with a transmitter. These days, the speaker is probably rarer than the radio.
Power is mains or via a 12V DC input (if you can find a plug to match the relevant socket!)
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| Matching speaker |
My own example of the SX-190 was purchased sight-unseen from an Australian Radio DX Club member’s deceased estate, subsequent to a couple of failed deals to acquire one of these over earlier months. It bears the “Realistic” badge, which is a little less desirable – tainted by the reputation of other radios sold through the Radio Shack and Tandy chains, such as the DX150/160 and other radio crimes (don’t shoot me, I know these sets have many fans!)
Some restoration work was clearly required, as the mains cable had been snipped off inside the receiver for reasons unknown. Once replaced, the receiver sprang to life, only requiring a bit of contact switch spray on the various front panel controls. The crystal calibrator did not seem to be working, which caused a little scratching of the head; until I realised that the whole circuit board was missing! Maybe I’ll pick up the relevant board at some time in the future.
The kindness of a fellow enthusiast resulted in subsequently obtaining a CD with the service/operating manuals, and a variety of modifications.
More recent outings (2021) are giving indications of mains hum. Time to whip out the filter caps!
Radio Shack Catalogue 1973 (courtesy WorldRadioHistory.com)
This receiver is an absolute pleasure to use, and I’m impressed by the incredible stability for something of its vintage, even when listening in sideband. It also looks great on the shelf; the fascia and controls are brushed aluminium, and all have a positive feel. The tuning, in particular, is characterised by smoothly moving (brass) gears and no apparent backlash.
Closer scrutiny inside reveals that this example was put together by GRE (General Research of Electronics) of Chiba, Japan – which also manufactured the DX160 and some subsequent own-branded land/marine radios. GRE was a go-to manufacturer of the time for US firms, producing badge-engineered items for such well-known brands as Uniden, and even R.L. Drake. Yes, Virginia, not all Drakes have the “Made in USA” claim to fame. We’ll discuss the classic SSR-1 on a future occasion!
The design of the SX-190 is, however, more than adequate for an “everyman” level set, despite (or maybe because of) its pedigree. Selectivity of 4 kHz (at -6dB) is respectable for the period, and sensitivity of less than 1 µV AM (0.5 µV SSB), means that this is quite a hot receiver, though drops off on the higher frequencies noticeably.
Various “hot-rodders” have sought to drop out the original front-end JFETs in favour of something more modern, in an attempt to address this, but I don’t know whether it actually helps, or just gives more prominence to noise and artifacts.
Stock on the second-hand market is quite healthy. In Australia we can expect to pay AUD $100-$150, depending on condition. I’ve seen them go for a lot more in the U.S., despite an abundance of stock. A darling of swap meets, and hamfests, these sets are frequently gathering dust (or rust!) in the corner of hobbyist sheds.
Improvements that can be made include changes to the rather jumpy S-meter indication, improved AGC attack time, reduction to amplifier hum and changing the crystal calibrator to a 5 kHz interval.
That said, purist collectors will want to gaze affectionately upon their SX-190, rather than try to transform it into a Watkins-Johnson wannabe. Some things are best left alone.
Like many older sets, the SX-190 is desirable more for what it is than what it does. Certainly, a nice improvement to the aesthetics of any baby boomer shack!
A scan of the service manual can be found at:
FURTHER READING:
- Shortwave Receivers: Past and Present, 4th Edition, Page 44
- Popular Electronics, November 1972 (Page 30)
- For current owners of the rig, check out the compendium of SX/AX-190 resources, modifications, technical specs, reviews, and the user manual on the RigPics website. This useful collection would be worth downloading, just in case it is removed from the site at a later date! http://radiopics.com/1.%20Manuals/Allied/Allied_SX-190-Info-Oct02.pdf
(This article first appeared in the October 2009 issue of the Australian DX News)
Once again, many thanks to Craig Seager for contributing this retro review to the MEDXR blog, and helping to keep the memories of radio alive!
Missed the other Retro Reviews? Check them all out by clicking below:
Retro Receiver Review # 1 - The DANSK RX4000
Retro Receiver Review # 2 - The HITACHI KH-3800W
Retro Receiver Review # 3 - The SCHAUB LORENZ ITT TOURING T104A RECEIVER
Retro Receiver Review # 4 - The RACAL RA6790/GM
Retro Receiver Review # 5 - The REALISTIC (RADIO SHACK) DX160
Retro Receiver Review # 6 - The KENWOOD QR 666
Retro Receiver Review # 7 - The RODHE & SCHWARZ EK890
Retro Receiver Review # 8 - The YAESU FR101S
Retro Receiver Review # 9 - The SELENA VEGA B206
Retro Receiver Review # 10 - The DRAKE SPR-4
Retro Receiver Review # 11 - The NATIONAL RF-5000
Retro Receiver Review # 12 - The YAESU FRG-100
Retro Receiver Review # 13 - The MARC NR-82 F1
Retro Receiver Review # 14 - The MURPHY B40
Retro Receiver Review # 15 - The STROMBERG CARLSON AWP-8
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© Rob Wagner, Mount Evelyn DX Report, and contributors 2012-2023
My first really serious rig. I added a 90 m crystal to my rig. Only replaced with a Collins R390A.
ReplyDeleteThe SX-190 still has a good following among collectors these days -- decades ago it was used by some of the top U.S. DX'ers for specialty listening, for example to Latin America and African stations. Occasionally one sees LNIB examples of the 190 show up on the used market. Always ask questions before buying!
ReplyDeleteI had a Allied SX-190 in the early 70's while in high school. Definitely a great radio and DX machine during its day, although I did find it a little deaf on the higher frequencies. Enjoy!
ReplyDeleteI worked at Radio Shack in the early 70's and was going to college at the same time. One of the perks of working at RS is I could DX with the radios all I wanted. I loved the SW radios that we had on display, only I couldn't afford them. I had about a 50 ft. Long wire antenna on the roof with an antenna switch made from parts right off of the walls. 73 KA6JMM
ReplyDelete