Roberts Rambler tuning query....or is it ? - UK Vintage Radio Repair and Restoration Discussion Forum

martinhog · 3rd May 2017, 10:09 pm

Good evening, I have been working on a nice Roberts Rambler and it is working well. I have a query though, if I turn the tune control quickly, as you tune past a station, you just hear a very loud crackle from the speaker. However, if I turn the tube control rather slowly, it is possible to tune in all the available stations. On my 505 and RT22, I don't notice this effect. Is this peculiar to the Rambler ? Once tuned it plays for hours on end. I have the circuit information from this forum. All comments are appreciated , thank you.

ronbryan · 3rd May 2017, 10:14 pm

This effect is normally due to bad contact to the rubbing contacts on the rotor of the tuning capacitor.

Spraying into one of the holes in the solid dielectric capacitor with a little squirt of switch cleaner such as Servisol or De-Oxit and rotating the tuning control will improve the situation. The fluid will normally evaporate in a few days. Warmth from the boiler or airing cupboard will help to dry it out.

Ron

martinhog · 4th May 2017, 7:57 pm

Thanks for your advice Ron. Have just squirted some servisol into the tuning capacitor and wound it back and forth. I will report back when it has dried out. Thanks again. Regards Martin

martinhog · 8th May 2017, 6:20 pm

Thanks for the advice ronbryan, I let the servisol dry over the weekend, the Rambler now tunes beautifully ! . All the best.

3rd May 2017, 10:09 pm	#1
martinhog Pentode Join Date: Aug 2005 Location: Ashford, Kent, UK. Posts: 204	Roberts Rambler tuning query....or is it ? Good evening, I have been working on a nice Roberts Rambler and it is working well. I have a query though, if I turn the tune control quickly, as you tune past a station, you just hear a very loud crackle from the speaker. However, if I turn the tube control rather slowly, it is possible to tune in all the available stations. On my 505 and RT22, I don't notice this effect. Is this peculiar to the Rambler ? Once tuned it plays for hours on end. I have the circuit information from this forum. All comments are appreciated , thank you.

3rd May 2017, 10:14 pm	#2
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,959	Re: Roberts Rambler tuning query....or is it ? This effect is normally due to bad contact to the rubbing contacts on the rotor of the tuning capacitor. Spraying into one of the holes in the solid dielectric capacitor with a little squirt of switch cleaner such as Servisol or De-Oxit and rotating the tuning control will improve the situation. The fluid will normally evaporate in a few days. Warmth from the boiler or airing cupboard will help to dry it out. Ron Last edited by ronbryan; 3rd May 2017 at 10:20 pm.

4th May 2017, 7:57 pm	#3
martinhog Pentode Join Date: Aug 2005 Location: Ashford, Kent, UK. Posts: 204	Re: Roberts Rambler tuning query....or is it ? Thanks for your advice Ron. Have just squirted some servisol into the tuning capacitor and wound it back and forth. I will report back when it has dried out. Thanks again. Regards Martin

8th May 2017, 6:20 pm	#4
martinhog Pentode Join Date: Aug 2005 Location: Ashford, Kent, UK. Posts: 204	Re: Roberts Rambler tuning query....or is it ? Thanks for the advice ronbryan, I let the servisol dry over the weekend, the Rambler now tunes beautifully ! . All the best.