Dynatron T99 Tuner

[pwdrive]

No schematic found yet.....The front panel layout seems the same as this Dynatron Merlin:

http://www.bamfords-auctions.co.uk/buyin...ronted-ca/

The Ether Conqueror series also has some similarity to the front panel layout:

http://www.worthpoint.com/worthopedia/dy...-512200336

Lawrence.

[Alistair D]

Found some information on the Dynatron K129 radiogram that  shows it has a T69 tuner.

http://www.vintage-radio.net/forum/showt...hp?t=54595

Not sure if that will be the same as the B129 radio. The D suffix in Lawrence's link might also be important as it could imply an updated version.

Will keep looking.

Al

[Cardigan]

The K129 is an Ether Conqueror in 'Regency' cabinet (I think). The suffix letters on the tuners  do denote differing versions, but it's not unknown for them to differ amongst themselves!

For example, the T69A differs from the T69B by not having a whistle filter and the decoupling of the AF triode is by a 10uf electrolytic capacitor in the -A, but a 1uf paper capacitor in the -B.

[Alistair D]

Here is another link that might be an avenue for investigation

http://vintage-radio.net/forum/showthread.php?t=29662

Al

[Murphyv310]

Hi.
For some reason due to a senior moment I see that the Frequency changer is a ECH81 in the tuner............... It should be a X79!!!!
These valves are not a direct equivalent being very slightly different in pin connections although the ECH81 will normally work. I wonder though if this the reason the dial calibration is out a bit.
So do I have an X79.......... not on your nelly puff. I'll put a request in the wanted and have a shuftie on E-bay.

[AlanBeckett]

Not one I've got either, and only a second had kit on ebay.
The Valve Museum lists CV5115 as equivalent but they seem equally thin on the ground.

Alan

[Excessive Leakage]

It appears that the US equivalent is the 6AE8, http://www.radiomuseum.org/tubes/tube_6ae8.html , which is also an elusive valve.

The following may be of interest if you struggle to find the X79 http://antiqradio.com/post_6ae8-replacement.html

Cheers

Adam

[Murphyv310]

Hi.
Well I decided to pop up into the loft as something in the back of my mind made me think I have an X79 up there. Half an hour of looking through boxes that had not been recorded found a nice NOS X79 and a pull.
I then fitted the NOS valve into the tuner and I was rewarded with good results. Now I did see a mod to the FC base, a link from pin 7 to pin 9 which I removed, in fact the IC (Internal connection) in the X79 is actually between these pins, the removal though was done in case it caused stray capacitance.
With the X79 the tracking on SW1 & 2 is spot on now, on MW & LW it is perfect at the high frequency end of the band, better at the low frequency end of MW but not so good at the LF end of LW.
Now there is a common series cap to the oscillator tuning cap that is only switched in on MW & LW and I would think it has changed in value downwards, this would explain the mis-tracking on Medium & Long waves.
Tomorrow I'll remove the cap and measure it, there is no marking so I have no idea of its value, I'm hoping its a preferred value type that has gone low value.
I'll check and come back with my findings.

[Murphyv310]

   
   
   

Hi.
Well I'm now happy with the tuner.
There were a few of the TCC metalmite found to be leaky, this was effecting the AVC, I've replaced them and fitted a NOS Magic Eye.
The tracking on MW & LW are slowly drifting back to where they should be, so I'm thinking the coils on MW & LW were slightly damp effecting their "Q" the dial is now only a couple of degrees out and I'm sure with use it will become spot on. Alignment hasn't been touched and I'll be leaving it well alone.
I've had this before and done re-alignment only to do it again later as it has drifted the opposite way weeks later.
The tuner was brilliant before I replaced some caps and way out of spec resistors now it's even better especially with the correct valve line up.

Next is a suitable case/cabinet and output stage.

[Excessive Leakage]

I like the look of that Dynatron! Made just down the road from me, I think.

I have been most unlucky with those Metalmites and have had to replace almost all I have encountered so far.

Cheers

Adam