aeg telefunken e1800a receiver racal ra-3701 ra-3791 ra-1792 harris RF590 watkins johnson 8711 rohde schwarz ek070 radio

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Racal RA3791

This is a most capable model and the last of Racals receivers with a real operators front panel

An under rated receiver (maybe because there are not many around in private hands yet). But take a look at the operating manual and you will see that many of its facilities can be programmed for your specific requirements, making this a very versatile unit

This example is badged on the rear with Thales so it probably dates from about 2000-2001

This receivers' main tuning knob has been replaced with an RA3701/RA1792 type and weighted for a smoother action. The tuning encoder fitted to this model is a HP (now Avago) high quality device

Under test and on-air conditions, this model is as good as any other that I have used. Sensitivity is very good. You will hear a CW note down to -140dBm. (That's not the measured MDS in any particular B/W). This is similar to the WJ8711

Ergonomics are very nice and its channel store, view and recall are very intuitive

The front panel is solidly constructed and much improved on the WJ8711. Performance is similar (but better in some areas) to the WJ8711 (see controls). The chassis is also much improved over the WJ8711. Thicker and anodized aluminium is used throughout

A nice feature is the ability to program the tuning encoder not only for different frequency step sizes (as is normal for this type of radio), but also the number of steps per knob rotation, (see the controls page). Racal have retained their variable tuning rate and in addition, a specific step size can now be programmed, e.g.; 9KHz for MW/LW AM tuning. Up to 100 IF filters may be programmed for use with different bandwidths. And the SSB filters are setup with upper and lower cutoff frequencies. More about this on the controls page

Without technical manual/s it is difficult to detail the specific architecture of this receiver. However its design is similar to the WJ8711. One RF and one digital card plus a front panel. The digital card is fitted with 3 Motorola digital signal processors. There is space for a 4th DSP device, which I believe is used for the optional automatic notch filter

AGC performance regarding attack time is better than many other DSP receivers of this period. In fact this parameter was my initial concern before I purchased this model However I was not disappointed. The AGC response of this receiver is wonderful. No attack pops on leading CW characters or SSB syllables. AGC hold and decay times are also programmable in their fast, medium and slow AGC modes. See controls

Racal have once again done a very fine job of their final front panel HF receiver

 

 
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2018 by Andrew Cygan