Roberts R707 question - UK Vintage Radio Repair and Restoration Discussion Forum

akuram1 · 4th Nov 2017, 9:02 pm

I have just come into possession of this very nice radio.
My question is at serial number 63727 what transistors will be in the IF module.
The radio was working on FM but nothing on M/L bands.
I have found the problem is at two dry joints on wire links to switch unit. I haven't soldered them yet but when pushed to connect the radio is great on all bands. Needs a good clean etc.

ukcol · 4th Nov 2017, 9:29 pm

]The R707 employs a Mullard LP1164 IF module and an LP1179/2 tuner module.

The IF module contain the infamous AF11x series transistors. There are multiple threads on these transistors, just search "AF11x" if you are not familiar with the tin whisker problem.
The tuner module includes a BF194 and a BF200, the BF194 is a lockfit type.
The audio amplifier also employs Mullard silicon lockfit types (BC158, BC148 and BC149).

Lockfit types are reported to give trouble, although I haven't experienced it myself. The driver and output stages employ germanium types (OC71/T7 AC187 and AC188).

Your question implies there may be more than one version of the R707. AFAIK this is not the case but others may know different.

Service info here.

akuram1 · 4th Nov 2017, 10:31 pm

Actually I have read all I could find about the 707 on this site so I am aware of the AF11's problems which this radio does not seem to suffer from yet.
I just want to know if with this serial no maybe it would have a later version using AF12 series in the module.
Thanks for your information anyway.

Philips210 · 4th Nov 2017, 10:38 pm

Hi.

I'm not sure but if the Mullard LP1164 IF module contains AF12x transistors I believe there is a suffix to the LP1164 designation, something like LP1164/1 or LP1164/2. Perhaps someone can clarify this.

Regards
Symon.

ronbryan · 4th Nov 2017, 11:56 pm

If the LP1164/1 IF module has an 02 following the module number, then it was manufactured with AF12x transistors. See the attached photo.

Of course any module could have been subsequently modified to incorporate AF12x devices.

Ron

akuram1 · 5th Nov 2017, 7:13 pm

The module fitted to this radio is a LP1164/1 S and below it 73 42.
It works very well at the moment.
I just was enquiring because 63727 is a highish serial number and thought someone could know.
Lot of tidying up to do but it is looking good so far.

'LIVEWIRE?' · 5th Nov 2017, 8:11 pm

The 73 42 is almost certainly a Date code, meaning it was made in October 1973. As such it will have AF11x transistors inside.

David G4EBT · 5th Nov 2017, 8:38 pm

There's a useful PDF file of data on some of the Mullarrd modules here:

http://www.electrojumble.org.uk/DATA...P1155-1174.pdf

Hope that might be of interest.

4th Nov 2017, 9:02 pm	#1
akuram1 Pentode Join Date: Sep 2009 Location: Dundee, UK. Posts: 158	Roberts R707 question I have just come into possession of this very nice radio. My question is at serial number 63727 what transistors will be in the IF module. The radio was working on FM but nothing on M/L bands. I have found the problem is at two dry joints on wire links to switch unit. I haven't soldered them yet but when pushed to connect the radio is great on all bands. Needs a good clean etc.

4th Nov 2017, 9:29 pm	#2
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: Roberts R707 question ]The R707 employs a Mullard LP1164 IF module and an LP1179/2 tuner module. The IF module contain the infamous AF11x series transistors. There are multiple threads on these transistors, just search "AF11x" if you are not familiar with the tin whisker problem. The tuner module includes a BF194 and a BF200, the BF194 is a lockfit type. The audio amplifier also employs Mullard silicon lockfit types (BC158, BC148 and BC149). Lockfit types are reported to give trouble, although I haven't experienced it myself. The driver and output stages employ germanium types (OC71/T7 AC187 and AC188). Your question implies there may be more than one version of the R707. AFAIK this is not the case but others may know different. Service info here. Last edited by ukcol; 4th Nov 2017 at 9:36 pm.

4th Nov 2017, 10:31 pm	#3
akuram1 Pentode Join Date: Sep 2009 Location: Dundee, UK. Posts: 158	Re: Roberts R707 question Actually I have read all I could find about the 707 on this site so I am aware of the AF11's problems which this radio does not seem to suffer from yet. I just want to know if with this serial no maybe it would have a later version using AF12 series in the module. Thanks for your information anyway.

4th Nov 2017, 10:38 pm	#4
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Roberts R707 question Hi. I'm not sure but if the Mullard LP1164 IF module contains AF12x transistors I believe there is a suffix to the LP1164 designation, something like LP1164/1 or LP1164/2. Perhaps someone can clarify this. Regards Symon.

4th Nov 2017, 11:56 pm	#5
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,959	Re: Roberts R707 question If the LP1164/1 IF module has an 02 following the module number, then it was manufactured with AF12x transistors. See the attached photo. Of course any module could have been subsequently modified to incorporate AF12x devices. Ron Attached Thumbnails

5th Nov 2017, 7:13 pm	#6
akuram1 Pentode Join Date: Sep 2009 Location: Dundee, UK. Posts: 158	Re: Roberts R707 question The module fitted to this radio is a LP1164/1 S and below it 73 42. It works very well at the moment. I just was enquiring because 63727 is a highish serial number and thought someone could know. Lot of tidying up to do but it is looking good so far.

5th Nov 2017, 8:11 pm	#7
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: Roberts R707 question The 73 42 is almost certainly a Date code, meaning it was made in October 1973. As such it will have AF11x transistors inside.

5th Nov 2017, 8:38 pm	#8
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: Roberts R707 question There's a useful PDF file of data on some of the Mullarrd modules here: http://www.electrojumble.org.uk/DATA...P1155-1174.pdf Hope that might be of interest. __________________ David. BVWS Member. G-QRP Club member 1339.