On Thursday, 15 October 2015 04:17:48 UTC+11, Phil Hobbs wrote:
> On 10/14/2015 10:36 AM, John Larkin wrote:
> > On Wed, 14 Oct 2015 08:51:08 -0400, Phil Hobbs
> > <pcdhSpamMeSenseless@electrooptical.net> wrote:
> >> On 10/14/2015 06:38 AM, tabbypurr@gmail.com wrote:
> >>> On Tuesday, 13 October 2015 23:28:17 UTC+1, John Larkin wrote:
<snip>
> The combination of high voltage drive and very low plate capacitance
> meant that I could easily pulse the grids and then disconnect in a
> microsecond or so. A relay would have worked except for being way too slow.
Relays aren't always slow. IIRR there was a time domain reflectometer that used a mercury-wetted reed relay to generate its sub-nanosecond rise-time pulse.
Getting them to turn on or off at a specific instant is trickier. They aren't so much slow as ill-coordinated.
--
Bill Sloman, Sydney
Reply by Phil Hobbs●October 14, 20152015-10-14
On 10/14/2015 10:36 AM, John Larkin wrote:
> On Wed, 14 Oct 2015 08:51:08 -0400, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> On 10/14/2015 06:38 AM, tabbypurr@gmail.com wrote:
>>> On Tuesday, 13 October 2015 23:28:17 UTC+1, John Larkin wrote:
>>>
>>>> I'd still seriously consider tubes if I had to make a 30 KV amplifier.
>>>>
>>>> A 1B3 is a nice slow amplifier if the input is the filament voltage.
>>>
>>> Memory on this not what it should be, but I thought drawing max possible i from a filament shortened its life greatly.
>>>
>>>
>>> NT
>>>
>>
>> It'll trash an oxide cathode in a gridded tube, for sure. OTOH the 1B3
>> has no grid, so one gathers that it's meant to operate in the
>> cathode-limited condition. The datasheet at
>> http://www.datasheetarchive.com/dl/Scans-008/Scans-00173345.pdf
>> just says that the cathode is a "coated filament".
>>
>> I have OCRed copies of Herrmann & Wagener's two volumes on "The
>> Oxide-Coated Cathode" up on my website:
>>
>> http://electrooptical.net/OldBooks/OxideCoatedCathodV1.djvu
>> http://electrooptical.net/OldBooks/OxideCoatedCathodeVol2.djvu
>>
>> Cheers
>>
>> Phil Hobbs
>
> I used to use a 1B3 with variable filament voltage (pot and flashlight
> battery, long insulated shaft) to be a variable-conduction rectifier,
> to charge flashtube capacitors to ballpark 8KV, manually set. Seemed
> reliable, even starting with old 1B3's.
Well, a rectifier that couldn't rectify very long wouldn't be much use,
for sure. I don't know what they made 5U4 cathodes out of, either.
H & W talk about the damage mechanism being mostly internal arcing due
to the voltage drop across the thickness of the oxide layer, which I
hadn't thought about, but the pictures on P. 109 would seem to bear out.
Seems like that would get worse at low filament temperature.
Tubes are fun. My last tube circuit was in about 1988--I used an 811A
to drive some grids in an electrostatic drift experiment. (I was trying
to use a laser-produced plasma to create air ions inside semiconductor
process tools. An enthusiasm of my then manager's.)
The combination of high voltage drive and very low plate capacitance
meant that I could easily pulse the grids and then disconnect in a
microsecond or so. A relay would have worked except for being way too slow.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Reply by John Larkin●October 14, 20152015-10-14
On Wed, 14 Oct 2015 09:47:59 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
There's no reason to both bias up MN2 with DZ1 (silly reference
designators!) and use a depletion fet.
This still has a lot of quiescent power dissipation, in R3 and the
fets.
On Wed, 14 Oct 2015 08:51:08 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
>On 10/14/2015 06:38 AM, tabbypurr@gmail.com wrote:
>> On Tuesday, 13 October 2015 23:28:17 UTC+1, John Larkin wrote:
>>
>>> I'd still seriously consider tubes if I had to make a 30 KV amplifier.
>>>
>>> A 1B3 is a nice slow amplifier if the input is the filament voltage.
>>
>> Memory on this not what it should be, but I thought drawing max possible i from a filament shortened its life greatly.
>>
>>
>> NT
>>
>
>It'll trash an oxide cathode in a gridded tube, for sure. OTOH the 1B3
>has no grid, so one gathers that it's meant to operate in the
>cathode-limited condition. The datasheet at
>http://www.datasheetarchive.com/dl/Scans-008/Scans-00173345.pdf
>just says that the cathode is a "coated filament".
>
>I have OCRed copies of Herrmann & Wagener's two volumes on "The
>Oxide-Coated Cathode" up on my website:
>
>http://electrooptical.net/OldBooks/OxideCoatedCathodV1.djvu
>http://electrooptical.net/OldBooks/OxideCoatedCathodeVol2.djvu
>
>Cheers
>
>Phil Hobbs
I used to use a 1B3 with variable filament voltage (pot and flashlight
battery, long insulated shaft) to be a variable-conduction rectifier,
to charge flashtube capacitors to ballpark 8KV, manually set. Seemed
reliable, even starting with old 1B3's.
Reply by Phil Hobbs●October 14, 20152015-10-14
On 10/14/2015 08:51 AM, Phil Hobbs wrote:
> On 10/14/2015 06:38 AM, tabbypurr@gmail.com wrote:
>> On Tuesday, 13 October 2015 23:28:17 UTC+1, John Larkin wrote:
>>
>>> I'd still seriously consider tubes if I had to make a 30 KV amplifier.
>>>
>>> A 1B3 is a nice slow amplifier if the input is the filament voltage.
>>
>> Memory on this not what it should be, but I thought drawing max
>> possible i from a filament shortened its life greatly.
>>
>>
>> NT
>>
>
> It'll trash an oxide cathode in a gridded tube, for sure. OTOH the 1B3
> has no grid, so one gathers that it's meant to operate in the
> cathode-limited condition. The datasheet at
> http://www.datasheetarchive.com/dl/Scans-008/Scans-00173345.pdf
> just says that the cathode is a "coated filament".
>
> I have OCRed copies of Herrmann & Wagener's two volumes on "The
> Oxide-Coated Cathode" up on my website:
>
> http://electrooptical.net/OldBooks/OxideCoatedCathodV1.djvu
> http://electrooptical.net/OldBooks/OxideCoatedCathodeVol2.djvu
Page 109 of Volume 1 shows dead cathodes.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Reply by Phil Hobbs●October 14, 20152015-10-14
On 10/14/2015 06:38 AM, tabbypurr@gmail.com wrote:
> On Tuesday, 13 October 2015 23:28:17 UTC+1, John Larkin wrote:
>
>> I'd still seriously consider tubes if I had to make a 30 KV amplifier.
>>
>> A 1B3 is a nice slow amplifier if the input is the filament voltage.
>
> Memory on this not what it should be, but I thought drawing max possible i from a filament shortened its life greatly.
>
>
> NT
>
On Tuesday, 13 October 2015 23:28:17 UTC+1, John Larkin wrote:
> I'd still seriously consider tubes if I had to make a 30 KV amplifier.
>
> A 1B3 is a nice slow amplifier if the input is the filament voltage.
Memory on this not what it should be, but I thought drawing max possible i from a filament shortened its life greatly.
NT
Reply by John Larkin●October 13, 20152015-10-13
On Tue, 13 Oct 2015 14:20:36 -0700 (PDT),
grahamholloway@graham65.plus.com wrote:
>On Sunday, 11 October 2015 17:35:59 UTC+1, Jim Thompson wrote:
>> HV OpAmp...
>>
>> <http://www.analog-innovations.com/SED/HV_OpAmp_2015-10-11.png>
>>
>> Can be built to arbitrary HV supplies, just change Q1 and Q2 to higher
>> voltage devices.
>>
>> ...Jim Thompson
>> --
>> | James E.Thompson | mens |
>> | Analog Innovations | et |
>> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
>> | San Tan Valley, AZ 85142 Skype: skypeanalog | |
>> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
>> | E-mail Icon at http://www.analog-innovations.com | 1962 |
>>
>> I love to cook with wine. Sometimes I even put it in the food.
>
>When I saw this thread I thought, ah-ah Kilovolts. But, no.
>
>Anyway I thought I must add that I made an amplifier with an 18KV positive rail for driving a penetration phosphor CRT. Colour change with variation of the final HT, 8 to 16 KV. In the mid/late 60's I used a pair of experimental MOV triodes (valves/tubes) in direct-coupled class AB driven from a 741 (what's that)to perform the colour change. We had to modulate the deflection system in synchronism to maintain the picture size. It worked satisfactorily so we thought we had better get rid of the valves/tubes, because it was going to have to fly. For the "solid-state" version we ended up using a stack of TV line output transistors (BUY 69 rings a bell)in the output stage. Interesting times.
I'd still seriously consider tubes if I had to make a 30 KV amplifier.
A 1B3 is a nice slow amplifier if the input is the filament voltage.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by ●October 13, 20152015-10-13
On Sunday, 11 October 2015 17:35:59 UTC+1, Jim Thompson wrote:
> HV OpAmp...
>
> <http://www.analog-innovations.com/SED/HV_OpAmp_2015-10-11.png>
>
> Can be built to arbitrary HV supplies, just change Q1 and Q2 to higher
> voltage devices.
>
> ...Jim Thompson
> --
> | James E.Thompson | mens |
> | Analog Innovations | et |
> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
> | San Tan Valley, AZ 85142 Skype: skypeanalog | |
> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
> | E-mail Icon at http://www.analog-innovations.com | 1962 |
>
> I love to cook with wine. Sometimes I even put it in the food.
When I saw this thread I thought, ah-ah Kilovolts. But, no.
Anyway I thought I must add that I made an amplifier with an 18KV positive rail for driving a penetration phosphor CRT. Colour change with variation of the final HT, 8 to 16 KV. In the mid/late 60's I used a pair of experimental MOV triodes (valves/tubes) in direct-coupled class AB driven from a 741 (what's that)to perform the colour change. We had to modulate the deflection system in synchronism to maintain the picture size. It worked satisfactorily so we thought we had better get rid of the valves/tubes, because it was going to have to fly. For the "solid-state" version we ended up using a stack of TV line output transistors (BUY 69 rings a bell)in the output stage. Interesting times.