Mains transformer for Roberts RFM3 - UK Vintage Radio Repair and Restoration Discussion Forum

Finnlong · 23rd Mar 2017, 3:21 pm

I was recently asked by my mother to see if I could "fix" and do up her Roberts rfm3 portable radio. I opened it up to find that there was no mains socket inside (the housing was there but no metal on it and the wires were taped up at the end). Finding it difficult to find a replacement socket I decided to do a big no no - buy one online and use it for parts. (then keep the bought one for myself afterward - use batteries) However, I found that seemingly very few work off mains as they don't "have a mains transformer" inside them. Does anyone know how I would go about making our present one mains capable? And what the mains transformer would look like on one of these?
Many thanks in advance!

toshiba tony · 23rd Mar 2017, 4:34 pm

One of our gurus will help but as long as you avoid SMPS supplies as they send so much hash out, esp. over LW\MW. Has it an external DC socket? If not you will simply have to do a bit of doctoring, your original battery was likely to be a PP9, if so you will probably find a psu you can fit inside the case. Just avoid smps.

Paul_RK · 23rd Mar 2017, 6:17 pm

I don't think any RFM3s will have been produced with mains supply components inside, but most or all have a socket for a 9 volt external DC supply, centre pin negative. The PU9-B was Roberts' own power supply for the sets - http://www.ebay.co.uk/itm/PU9-B-240v...YAAOSwWxNYvXva is an example. Cheaper good options could be found especially if you're up for obtaining and wiring the right DC input jack, but, as Tony says, SMPS supplies - generally smaller and much lighter - are best avoided because of the interference they generate. Beware sellers who may use the PU9 / PU9B type number in describing their SMPS power units.

Paul

23rd Mar 2017, 3:21 pm	#1
Finnlong Retired Dormant Member Join Date: Mar 2017 Location: Galway, Ireland Posts: 1	Mains transformer for Roberts RFM3 I was recently asked by my mother to see if I could "fix" and do up her Roberts rfm3 portable radio. I opened it up to find that there was no mains socket inside (the housing was there but no metal on it and the wires were taped up at the end). Finding it difficult to find a replacement socket I decided to do a big no no - buy one online and use it for parts. (then keep the bought one for myself afterward - use batteries) However, I found that seemingly very few work off mains as they don't "have a mains transformer" inside them. Does anyone know how I would go about making our present one mains capable? And what the mains transformer would look like on one of these? Many thanks in advance!

23rd Mar 2017, 4:34 pm	#2
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: Mains transformer for Roberts RFM3 One of our gurus will help but as long as you avoid SMPS supplies as they send so much hash out, esp. over LW\MW. Has it an external DC socket? If not you will simply have to do a bit of doctoring, your original battery was likely to be a PP9, if so you will probably find a psu you can fit inside the case. Just avoid smps.

23rd Mar 2017, 6:17 pm	#3
Paul_RK Dekatron Join Date: Nov 2003 Location: Fakenham, Norfolk, UK. Posts: 4,255	Re: Mains transformer for Roberts RFM3 I don't think any RFM3s will have been produced with mains supply components inside, but most or all have a socket for a 9 volt external DC supply, centre pin negative. The PU9-B was Roberts' own power supply for the sets - http://www.ebay.co.uk/itm/PU9-B-240v...YAAOSwWxNYvXva is an example. Cheaper good options could be found especially if you're up for obtaining and wiring the right DC input jack, but, as Tony says, SMPS supplies - generally smaller and much lighter - are best avoided because of the interference they generate. Beware sellers who may use the PU9 / PU9B type number in describing their SMPS power units. Paul