Ace 358 FM Issues - UK Vintage Radio Repair and Restoration Discussion Forum

mark2collection · 5th Nov 2018, 4:22 pm

I'm currently in the 'throes' of resurrecting the above set.

Having put the set in a position where it could be safely tested before I replaced missing, worn or out of spec components in earnest, namely 'that' capacitor, & following some sanity checks, all appeared as you'd expect a vintage radio to appear after many years of storage (crackly switches/pots etc), it was around this time I noticed an FM oddity.

The FM scale starts at 87 MHz & finishes at 100 MHz, nothing odd about that. However, 'real' 88 MHz from my trusty generator appears on the dial around 94 MHz, & bearing in mind the set only goes up to 100 MHz, I can pick up Classic FM & Heart (Circa 103 MHz) with consummate ease.

Now this is where things begin to mess with the head. Anything below 94 MHz on the dial (so in real terms, 88 MHz), the set begins to pick up Heart again & just below 87 MHz on the dial, we have Classic FM, albeit, faded!

The original carbon-comps in the FM section were a mix of 'far too high' or a little lower than spec, replacing these & positioning them as per the originals has improved gain, but nothing else.

One cap in the front-end, a 6pF, actually read 4.0 pF out of circuit, replacing this has moved things down the scale, but not by much. Everything else looks ok, physically & electrically testing.

I've downloaded the 3 diagrams from the link at the top of this page, sadly it's not for this set, but it's almost close!

Any ideas out there guys? On FM it sounds great, picks up everything you'd expect of it, just not in the right place or seemingly, in the right order. LW/MW appears to work great too. The rest of the iffy capacitors have been replaced (mainly the amplifier stage) & some carbon comps in the AM section.

Any advice gratefully received.

Mark

dazzlevision · 5th Nov 2018, 5:19 pm

Have you applied some contact cleaner/lubricant to the tuning capacitor’s stator earthing spring contacts? I’ve had this cause strange symptoms as you described.

TrevorG3VLF · 5th Nov 2018, 5:30 pm

It looks as if the oscillator has been moved to get the frequencies which were out of range.
The set selects an upper sideband, 10.4MHz above the oscillator and a lower sideband 10.7MHz below the oscillator. So the same station will come in twice, spaced at 20.8MHz. It seems you can receive both of these.

The RF aerial circuit should select the appropriate sideband with strong attenuation of the wrong sideband. Some re-alignment would bring the set back to original if that is what you want.

5th Nov 2018, 4:22 pm	#1
mark2collection Hexode Join Date: Jul 2010 Location: Royal Berkshire, UK. Posts: 471	Ace 358 FM Issues I'm currently in the 'throes' of resurrecting the above set. Having put the set in a position where it could be safely tested before I replaced missing, worn or out of spec components in earnest, namely 'that' capacitor, & following some sanity checks, all appeared as you'd expect a vintage radio to appear after many years of storage (crackly switches/pots etc), it was around this time I noticed an FM oddity. The FM scale starts at 87 MHz & finishes at 100 MHz, nothing odd about that. However, 'real' 88 MHz from my trusty generator appears on the dial around 94 MHz, & bearing in mind the set only goes up to 100 MHz, I can pick up Classic FM & Heart (Circa 103 MHz) with consummate ease. Now this is where things begin to mess with the head. Anything below 94 MHz on the dial (so in real terms, 88 MHz), the set begins to pick up Heart again & just below 87 MHz on the dial, we have Classic FM, albeit, faded! The original carbon-comps in the FM section were a mix of 'far too high' or a little lower than spec, replacing these & positioning them as per the originals has improved gain, but nothing else. One cap in the front-end, a 6pF, actually read 4.0 pF out of circuit, replacing this has moved things down the scale, but not by much. Everything else looks ok, physically & electrically testing. I've downloaded the 3 diagrams from the link at the top of this page, sadly it's not for this set, but it's almost close! Any ideas out there guys? On FM it sounds great, picks up everything you'd expect of it, just not in the right place or seemingly, in the right order. LW/MW appears to work great too. The rest of the iffy capacitors have been replaced (mainly the amplifier stage) & some carbon comps in the AM section. Any advice gratefully received. Mark Last edited by mark2collection; 5th Nov 2018 at 4:31 pm. Reason: Clarity.

5th Nov 2018, 5:19 pm	#2
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,622	Re: Ace 358 FM Issues Have you applied some contact cleaner/lubricant to the tuning capacitor’s stator earthing spring contacts? I’ve had this cause strange symptoms as you described.

5th Nov 2018, 5:30 pm	#3
TrevorG3VLF Rest in Peace Join Date: Apr 2011 Location: Matlock, Derbyshire, UK. Posts: 1,378	Re: Ace 358 FM Issues It looks as if the oscillator has been moved to get the frequencies which were out of range. The set selects an upper sideband, 10.4MHz above the oscillator and a lower sideband 10.7MHz below the oscillator. So the same station will come in twice, spaced at 20.8MHz. It seems you can receive both of these. The RF aerial circuit should select the appropriate sideband with strong attenuation of the wrong sideband. Some re-alignment would bring the set back to original if that is what you want.