Hammarlund HQ170 Amateur Band Receiver

 A high quality American Amateur Band Communications Receiver from 1958

 

  Hammarlund Manufacturing Co.Inc. were first established in 1910. After WWII their range of HF, VHF and UHF receivers were beginning to take shape into a recognisable product range. The twin dial layout, with an S-meter sitting between them, of the HQ129 and Super-Pro of 1946 were to be echoed in later models such as the HQ170, made in 1959, shown here.

The SP600JX "Military Model" of 1952 with the same twin dial arrangement but with the S-meter an the left was clearly from the same stable, providing as before, and as the later HQ170 and 180, the 6-metre band.

The HQ170 is a triple conversion receiver made specifically for amateur band use. Because it uses valves which take time to warm up it includes a clock which can be set to turn on the receiver 30 minutes before it was needed in order to let the frequency stabilize.
 

 These two views let you see the large number of valves (16 + 5U4GT rectifier) and individually screened coils and RF transformers used in the design of the HQ170. The twin dials are driven together and are used only to provide clearer frequency markings. The four lower bands are on the left and the three higher, plus a logging scale, are on the right.
 

 The main tuning condenser is a proprietary product that seems to have been modified by Hammarlund by the removal of a rotor in each of the three sections. There's a nice flywheel for smooth tuning and, on the right you can see two complex rotary switches for receive bandwidth and sideband reception. The main waveband switch uses ceramic wafers and trimmers etc are neatly arranged. I can see two crystals, one soldered in place under the chassis and the second in a holder at the rear of the chassis.
 

 This example of the set was designed for the US market for 117 volts AC mains and requires a step-down transformer to operate it in the UK. I'm not sure whether the clock would work correctly on UK 50 cycle mains as 60 cyles is the US standard.
 

 Below, location of valves and details of IF adjustments ... version "A" (Note there are slight differences between the HQ170 and HQ170A, for example next to V11 there is a rectifier valve (V15) in the former which has been replaced by two silicon diodes in the "A" version).

 

 Below I've included circuits of both the HQ170 and HQ170A on three pages for each version. You can click on any picture to see a PDF of larger images.

 

 

 

 Now the HQ170A

 

 

 

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