EHT Rectifier 16HT128

[M0FYA Andy]

Does anybody have any data on this high-voltage rectifier, please?
I assume W.B. & S. Co. means Westinghouse Brake & Signal Company.
Many thanks,
Andy

[barrymagrec]

I have no data to hand but they look very much like ones I used to replace the valve EHT rectifier in a Cossor 1035 scope many years ago. 5mA rating and OK for the 2Kv EHT winding as far as I remember.

Worked well for a whiile but then went for a burton with a very unpleasant smell - could have been due to using two in parallel without matching but I didn`t know any better at the time.

[Maarten]

I think such stacks would have a sufficiently high internal resistance and the internal drops of the individual junctions statistically spread in such way that the total drop wouldn't be too different (on average!) between stacks. Using them in parallel should have a high chance of working fine without matching in my opinion.

[gingpeakin]

I've seen these run in pairs before.

Ging

[Marconi_MPT4]

Hi Andy,

I only have sketchy abridged data of the 16HTnnn range for 16HT12 and 16HT258. Maximum current rating is 8mA and minimum reservoir capacitor value is 4µF for 16HT12 and 0.2µF for 16HT258.

Now theorising on 16HT128 voltage rating; metal rectifiers are made up of segments and R.M.S input for 16HT12 is 180V and for 16HT258 is 3,865V, therefore could be possible to estimate that the input for 16HT128 might be 1920V.

My guess based on the data 16HT128 is rated at approximately 2kV, 8mA.

Cheers
Rich

[M0FYA Andy]

Thanks for the replies!
Rich, your approach makes sense, each segment rated at 15 volts.
Andy

[ms660]

Yes, 8mA for the 16HT series seems to be inferred here also, not the same as Andy's but 16HT28 and 16HT56 shown in the schematic in this article:

https://www.americanradiohistory.com...rch=%2216ht%22

EDIT: Post crossed.

Lawrence.

[barrymagrec]

Originally Posted by Maarten

I think such stacks would have a sufficiently high internal resistance and the internal drops of the individual junctions statistically spread in such way that the total drop wouldn't be too different (on average!) between stacks. Using them in parallel should have a high chance of working fine without matching in my opinion.

Indeed, but since the sticks were recovered from old equipment they may have been in significantly different condition. The Cossor took 8mA so I thought I was well in but who knows.

I was only about 16 at the time, keeping the 1035 running with only free parts was all part of a rich learning experience which included discovering how long the EHT cap stayed charged up when the bleeder chain was O/C.

[TrevorG3VLF]

I have just replaced a similar rectifier in a Telequipment scope with half a dozen 1N4007 diodes in series enclosed in a ball point pen tube.

[WME_bill]

Westinghouse EHT rectifier sticks.
I have found a full data sheets for these 1960/65 rectifier sticks.
I attach the data for the type 16EHT (8ma).
Congratulations to all, as it seems that your speculations upon ratings were quite correct.
It is interesting how the current load rating is specified so carefully for the nature of the circuit. And it gives a formula for calculating the smoothing capacitance.
I have similar data for type 36 (2ma), type 39 (100ua) and the later type K238 (8ma). Also for the Westcode type Z33 -Z39, the little single diode or doubler pairs used in odd corners of 1950/60 TV sets and also their Flat Contact cooled for usual HT purposes.
wme_bill

[turretslug]

The 2CL69 to 2CL77 series rectifiers (5mA, 4 to 20kV PIV) are inexpensive and widely available and, being fast recovery, are suited to HF as well as mains-derived EHT applications.

https://static.chipdip.ru/lib/957/DOC000957256.pdf

[M0FYA Andy]

WME_bill, many thanks for that catalogue!
Andy