Indentifying a VHF tuner - Clarke and Smith 88/10

[terry123]

Hi all

there have been a small number of threads on the above subject over the years and I had thought I'd seen most of them until I recently starting restoring a clarke and smith 88/10 FM schools set which dates from the mid 1950s. Its an early one in fact their first FM model, and it is fitted with one of these tuners of the type shown in the picture. (they used at least 2 other front ends in later 88 series of schools receiver). So my first thoughts were Philips ( the ad in fact suggests a major maker) but I have not been able to find anything closly resembling anything of theirs, so can anyone help or better still supply a circuit, or some clear photos of one both sides of the unit, as mine has been got at and while the set is presently working perfectly on AM now, FM is as dead as a dodo. The tuner is actually dated Nov 1954. Oh and it is not the ECC85 !



Thanks in advance for any help

Kind regards
Terry

[Nuvistor]

The IF transformer definitely has a Philips look to it, ECC81 perhaps?

http://www.r-type.org/exhib/aai0246.htm

[M0FYA Andy]

That picture looks very familiar - did the Jasonkit FM tuners use them?

Andy

[Herald1360]

Originally Posted by Nuvistor

The IF transformer definitely has a Philips look to it, ECC81 perhaps?

http://www.r-type.org/exhib/aai0246.htm

ECC81

Not the ECC85 as in that's not the problem rather than not an ECC85?

[terry123]

Hi definetely an ECC85 according to the ad and there is one in the Clarke and smith tuner as a later service replacement by the look of it as it has Mullards yellow print on the glass envolope. Tried a couple of new ones in it as well.


Regards


Terry

[terry123]

Just out of interest I tried an ECC81, no good so I'll stick with the ECC85.


Hoping there is a circuit out there, perhaps other setmakers used the same tuner unit in thier radio sets at the time so here's hoping .


Regards


Terry

[Leon Crampin]

The heater connections differ for the two valve types. Pin 9 is a heater centre tap for the '81 and a screen for the '85. If you use an ECC81 and the heater supply is connected to pins 4 and 5 only, the valve requires a 12.6 V supply. The '85 is far more commonly found in FM tuner heads.

Leon.

[vidjoman]

The advert clearly states it’s an ECC85. Don’t waste time trying anything else.

[terry123]

Yes an ECC85 is the correct valve, that I know , the ECC81 was never going to work but wanted to cover all tests


Thanks for everyones obsevations, just need a circuit now


Regards


Terry

[AC/HL]

This post suggests that the 88/10 was AM only, could this be an 88/12?
https://vintage-radio.net/forum/show...4&postcount=11
In which case there may be a schematic here: http://portabletubes.co.uk/boats/clarke.htm

[terry123]

Hi Bill

It is a model 88/10 an earlier version normally AM only but this one is FM as well, a rarer version.

I have the dyeline drawings for the 88/12 which appeared some what later and is a differant beast.



Regards


Terry

[Nuvistor]

Apologies for ECC81, put it down to hot weather and the lock down.

[AC/HL]

Originally Posted by terry123

It is a model 88/10 an earlier version normally AM only but this one is FM as well, a rarer version.

Yes, I thought that might be the case.

[Synchrodyne]

Perhaps that FM front end was a Dormer & Wadsworth (D&W) model?

In the Dormer & Wadsworth thread, https://www.vintage-radio.net/forum/...d.php?t=157235, it was established that:

1. Clarke and Smith did use D&W FM front ends in some models (post #5); and:

2. Haverson Surplus was involved with what appears to be a surplus sale of D&W FM front ends (post #16)

Originally Posted by M0FYA Andy

That picture looks very familiar - did the Jasonkit FM tuners use them?

From what information I have been able to assemble on Jason and Jasonkit tuners from start to finish, Jason did not use the single valve (ECC85) front end until the FMT4 of 1960, and that was the only case. The FMT4 was available only as a built model. The top Jasonkit model stayed at the FMT3 level until the end. As I understand it, Jason saw the two pentodes FM front ends as the best option for stability under home construction conditions.


Cheers,