09-01-2018, 05:44 PM
Well, that did take a while! The new filter was an exact match for the original, which made the gamble of an international purchase worthwhile. Today I carefully desoldered the old part, taking care not to damage what are very delicate PCB traces. This wasn't easy to remove, as it has an odd 5 pin design. The new filter slipped neatly into the board once the holes were cleaned, and it was a quick job to solder up.
The radio is now working beautifully, and has correct filtering on the upper and lower sidebands. Although the faulty filter was 4 kHz bandwidth, not the 2.2 kHz narrow "sideband" filter, it is in circuit in narrow mode, to help reject adjacent channels. Unfortunately, it had drifted in centre frequency, so was clipping the narrow filter rather than complementing. This was cutting the bass on lower sideband, and treble on upper sideband (and vice versa) - it sounded really wrong.
Very happy to have this gem of a radio back in fine fettle. I've owned it since new, bought from the company showroom, back when they were a flourishing business in the UK.
Ed
The radio is now working beautifully, and has correct filtering on the upper and lower sidebands. Although the faulty filter was 4 kHz bandwidth, not the 2.2 kHz narrow "sideband" filter, it is in circuit in narrow mode, to help reject adjacent channels. Unfortunately, it had drifted in centre frequency, so was clipping the narrow filter rather than complementing. This was cutting the bass on lower sideband, and treble on upper sideband (and vice versa) - it sounded really wrong.
Very happy to have this gem of a radio back in fine fettle. I've owned it since new, bought from the company showroom, back when they were a flourishing business in the UK.
Ed
I don't hold with furniture that talks.
