'Roberts' radio - what do these bits do? - UK Vintage Radio Repair and Restoration Discussion Forum

yesnaby · 6th Aug 2009, 9:07 pm

Hello,

Having fun with this radio that works on VHF but not on MW/LW.

Does anyone recognise the chassis, for which I have no circuit?

Also, what is the purpose of the three 'things' that stick out from the PCB at odd angles? They look like very miniature ferrite rods with a rigid rod having two lots of extremely fine copper windings. Two of the upper windings have short stubs suggesting they were once connected to something. One even has a fragment of fabric insulation on it. (I checked the similarly fine wires coming from the big ferrite rod, but these seem to be intact.)

Michael

mickjjo · 6th Aug 2009, 9:21 pm

They look like the type of trimmers that Philips were once famous for, the idea is to unwind the wire until the capacity is correct and then leave well alone........

.

Regards, Mick.

'LIVEWIRE?' · 6th Aug 2009, 9:28 pm

I may be wrong, but I suspect they are trimmer capacitors/inductors, in which the capacitance(and inductance!) is varied by adding/removing turns of wire to/from the winding. They are probably part of the VHF Tuner circuit, rather than the MW/LW side.
I don't recognise the model, though, so can offer no help there

PS- Mickjo beat me to it by about 5 minutes- is this a case of 'great minds thinking alike', not that I have a partiicularly great mind!!. Anyhow, Mick, of course those 'iductive caps'(or 'capacitive inductors') were one of Philips' many 'different' ways of doing things-another being the 'Beehive' Trimmers.

yesnaby · 6th Aug 2009, 9:46 pm

Hello,

Many thanks to you both, this has shed some light on the subject.

I'll have a go at fixing it, but don't feel inclined to spend too much time - I would do if it was a 'proper' Roberts. And there is no means of illuminating the scale, so it is not as 'pretty' as the real thing.

Michael

Sideband · 6th Aug 2009, 10:11 pm

Looks sort of late 60's to early 70's judging by the style of components. Some of the transistors look like Mullard/Philips BF194/195 or possibly BC148 types and those ceramic 'pin-up' capacitors with the coloured bands were also Philips/Mullard from about the same period.

Yes, those strange things are trimmers.

Rich.

6th Aug 2009, 9:07 pm	#1
yesnaby Octode Join Date: Jul 2005 Location: Newport, Gwent, UK. Posts: 1,623	'Roberts' radio - what do these bits do? Hello, Having fun with this radio that works on VHF but not on MW/LW. Does anyone recognise the chassis, for which I have no circuit? Also, what is the purpose of the three 'things' that stick out from the PCB at odd angles? They look like very miniature ferrite rods with a rigid rod having two lots of extremely fine copper windings. Two of the upper windings have short stubs suggesting they were once connected to something. One even has a fragment of fabric insulation on it. (I checked the similarly fine wires coming from the big ferrite rod, but these seem to be intact.) Michael Attached Thumbnails

6th Aug 2009, 9:21 pm	#2
mickjjo Rest in Peace Join Date: Jul 2004 Location: Dartford, Kent, UK. Posts: 1,661	Re: 'Roberts' radio - what do these bits do? They look like the type of trimmers that Philips were once famous for, the idea is to unwind the wire until the capacity is correct and then leave well alone........ . Regards, Mick.

6th Aug 2009, 9:28 pm	#3
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: 'Roberts' radio - what do these bits do? I may be wrong, but I suspect they are trimmer capacitors/inductors, in which the capacitance(and inductance!) is varied by adding/removing turns of wire to/from the winding. They are probably part of the VHF Tuner circuit, rather than the MW/LW side. I don't recognise the model, though, so can offer no help there PS- Mickjo beat me to it by about 5 minutes- is this a case of 'great minds thinking alike', not that I have a partiicularly great mind!!. Anyhow, Mick, of course those 'iductive caps'(or 'capacitive inductors') were one of Philips' many 'different' ways of doing things-another being the 'Beehive' Trimmers. Last edited by 'LIVEWIRE?'; 6th Aug 2009 at 9:34 pm. Reason: To add further comments!

6th Aug 2009, 9:46 pm	#4
yesnaby Octode Join Date: Jul 2005 Location: Newport, Gwent, UK. Posts: 1,623	Re: 'Roberts' radio - what do these bits do? Hello, Many thanks to you both, this has shed some light on the subject. I'll have a go at fixing it, but don't feel inclined to spend too much time - I would do if it was a 'proper' Roberts. And there is no means of illuminating the scale, so it is not as 'pretty' as the real thing. Michael

6th Aug 2009, 10:11 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: 'Roberts' radio - what do these bits do? Looks sort of late 60's to early 70's judging by the style of components. Some of the transistors look like Mullard/Philips BF194/195 or possibly BC148 types and those ceramic 'pin-up' capacitors with the coloured bands were also Philips/Mullard from about the same period. Yes, those strange things are trimmers. Rich. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....