Mullard LP 1164 schematic and layout

[ronbryan]

Having been left with a scrap LP 1164/1 FM/AM IF module removed from Howard's R707, I traced the circuit and have made a schematic, parts list and layout diagram. I'm posting them in case anyone has to fault find to component level and needs this info.

The LP1164/1 is a negative earth, 9V module, designed for use with external oscillator coils. It has many similarities with the LP1165 7V module, with differences mainly in the bias resistors. The LP1165 data has been posted on the forum by KeithsTV, under a Clarke and Smith thread
https://www.vintage-radio.net/forum/...27&postcount=6 , but I arrived at my info. independently and there are some minor differences in the schematics.

The module pin numbers in my schematic run from 10 to 24 as per the Roberts R707 service info, rather than 1 to 14 as used by the Mullard Technical Handbook outline diagram. I have no idea why two numbering systems exist, but it does cause confusion.

I found that when bench testing the LP1164/1, connected up to a R707 with short jumper wires, the local AM oscillator would not run unless the aerial circuits in the set were hooked up to the module as well as the oscillator circuits.

I would like to thank Edward (Igranic) for his assistance in converting the two Visio drawings into a single readable pdf document and Howard for supplying the original module.

Ron

[Neil F]

Luverly stuff, Ron - this must have taken ages

[Nickthedentist]

Yes, thanks for this amazing work, Ron.

I've taken the liberty of saving it to my PC, hope that's OK.

N.

[ukcol]

A very professional looking job. Well done Ron.

[Sideband]

Hi Ron. This is very useful information. As far as I am aware, this info has never been published and they were always like 'mystery boxes'.

Excellent stuff and much appreciated
Rich.

[MALC SCOTT]

Hi Ron, very helpfull of you. Cheers, Malc

[Mike Phelan]

Very impressive, Ron, and definitely one for me to save.

[ajs37]

give that man an ice cream! well done Ron!
Cheers
Andy

[FRANK.C]

Excellent work Ron. Thanks for sharing it.

Frank

[ronbryan]

Thank you all for your encouragement.

I find that tracing a circuit diagram from the printed circuit track pretty tedious and prone to error, but for the LP1164, I used a suggestion made by Edward (Igranic) which made the whole process a lot simpler and easier to check.

I took a photo of the solder side of the module, flipped it horizontally in Photoshop and printed it onto A4. I then compared the print with the component side of the module and pencilled the component positions and values on to it. It was then pretty straightforward to draw the circuit diagram from the marked up print by looking at the components and their interconnections. The only remaining task was to investigate the transformers and identify the diodes.

Ron

[Colin Boggis]

Great help Ron! Can you confirm one point - is VT1 the AM oscillator only?
Thanks,
Colin

[ronbryan]

Colin

Transistor TR1 in the LP1164/1 IF module is used as the second FM IF amplifier and the AM mixer/oscillator, in conjunction with external AM oscillator coils. The operating mode of the module is controlled by the radio band switches. The FM RF amplifier and FM mixer/oscillator are contained in a separate LP1179 tuner module, as is the two gang AM tuning capacitor.

For FM operation the IF module has pins 13 and 14 joined. This applies -9V to the top of FM IFT T1 and shorts the series connected AM oscillator coil collector winding and AM IFT T2. Module pins 15 and 23 are also joined, bypassing VT1 emitter resistor to +ve with 33nF capacitor C1.

For AM operation, pins 13 and 12 are joined, shorting the FM IFT T1. Pin 15 is switched to allow C1 to couple VT1 emitter to the AM oscillator coil emitter winding.

Ron

[Colin Boggis]

Thanks Ron.
I'm a bit more puzzled now as I have a Roberts R707 that's working well on FM but has no AM. As 470kHz IF goes through fine from the aerial socket I'd assumed AM oscillator was dead and probably the AF115. But if its working OK on FM maybe not!! I'll do a bit more research, having replaced the transistor "just in case"
More later...............
Colin

[Darren-UK]

Just a little reminder ; any looming questions/answers on possible R707 faults should be posted in a seperate thread. A search, as an aside, will find existing threads on the R707 and it's potential faults.

[Valvepower]

Hi All,

Firstly must say that’s a cracking bit of drawing and research into the LP1164 – nice job Ron. I kept thinking one day something will appear on this module.


I’ve a couple of these modules in the in the workshop and thought they would make an ideal IF strip for an AM superhet radio project using a set of Denco aerial (blue) interstage (yellow) and oscillator (red) coils, which I also have lying around the workshop. But there could be some issues with the way the emitter is coupled into the oscillator coil.

I’ve had a look at the circuit for the module and I noticed the configuration of the oscillator coil differs to that of the circuit in the Denco application notes, which is more orthodox. The circuit in the module has the lower end of the oscillator coil capacitvly coupled (22nF) into the emitter of the oscillator transistor VT1, whereas the Denco coil has the lower end of the oscillator coil connected directly in series with the emitter of the transistor.

The obvious thing would be to make a hook-up to see if it works, as I feel it maybe worth a try. But before doing so I wondered if there is anyone out there has any ideas on the different coupling methods.

The LP1164 circuit does resemble that of the AM/FM Receiver circuit in the Mullard Transistor Audio and Radio Circuits from 1969 with silicon transistors and changes to the bias component values.

Terry.