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21A and 22A for 555


Stan or Patricia Griffiths <w7ni@...>
 

morriso2002@yahoo.com.au wrote:

Timebase plugins however are not so easy to find - in fact if anyone
has a spare 21A/22A combo for disposal I would be happy to give them a
good home here in Melbourne Australia :-)

Morris
Hi Morris,

There was an extensive modification to the 21A and 22A tunnel diode triggers
at SN 11000. 21A and 22A timebases have the older tunnel diode trigger
circuitry in them from SN 7000 to SN 10999. I would stay away from those
unless they have had Mod Kit 040-0417-00 installed. The kit is very complex
and includes a double sided circuit board and lots of hard to find parts so
it would be almost impossible to try to put this kit together from scratch.
The early TD triggers were very unstable and I can remember being very
frustrated trying to get them adjusted so they would continue to operate
reliably.

They way to tell if the mod has been installed or not is too look in the
timebase in question on the top of the chassis and just behind the front
panel about an inch to see of the etched circuit board is installed there.
The early 21A and 22A timebases had a couple of short rows of the small notch
ceramic strips installed there with the early TD trigger circuits installed
on them.

Stan
w7ni@easystreet.com


morriso2002@...
 

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
morriso2002@y... wrote:
There was an extensive modification to the 21A and 22A tunnel diode
triggers

<snip>

I would stay away from
those
unless they have had Mod Kit 040-0417-00 installed.
Hi Stan,

Thanks for the advice. The only 21A/22A I have ever seen, which
belongs to a friend, has the later version triggers. These timebase
plugins are not easy to find and I suspect "beggars will have to be
choosers" if a pair ever turns up. Mind you, the 21/22 works very
nicely indeed.

Incidentally do you know if it is possible to mix a 21 and 22A or 21A
and 22 in the one mainframe?

Morris


Stan or Patricia Griffiths <w7ni@...>
 

Mixing 21,22,21A, 22A. Let me say I don't know of any reason why you
couldn't do it but I have never tried it . . .

I will keep my eyes open for some plugins for you. I just enlarged my
collection by an addtional 350 instruments (to a total of about 1100) so I
might just have some by the time I get all that stuff transported to my shop
. . .

Stan
w7ni@easystreet.com

morriso2002@yahoo.com.au wrote:

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
morriso2002@y... wrote:
There was an extensive modification to the 21A and 22A tunnel diode
triggers

<snip>

I would stay away from
those
unless they have had Mod Kit 040-0417-00 installed.
Hi Stan,

Thanks for the advice. The only 21A/22A I have ever seen, which
belongs to a friend, has the later version triggers. These timebase
plugins are not easy to find and I suspect "beggars will have to be
choosers" if a pair ever turns up. Mind you, the 21/22 works very
nicely indeed.

Incidentally do you know if it is possible to mix a 21 and 22A or 21A
and 22 in the one mainframe?

Morris

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morriso2002@...
 

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:

I will keep my eyes open for some plugins for you. I just enlarged
my
collection by an addtional 350 instruments (to a total of about
1100) so I
might just have some by the time I get all that stuff transported to
my shop

Amazing!! Thanks you very much, I would be very grateful if you could
find me a 21A/22A set.

Morris


Stan or Patricia Griffiths <w7ni@...>
 

Its going to be a couple of months before I get all the stuff here. I am
depending on you to remind me of this need you have for the 21A and 22A. Did
you say the early version would be OK or do you want only the later ones?

Stan
w7ni@easystreet.com

morriso2002@yahoo.com.au wrote:

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:

I will keep my eyes open for some plugins for you. I just enlarged
my
collection by an addtional 350 instruments (to a total of about
1100) so I
might just have some by the time I get all that stuff transported to
my shop

Amazing!! Thanks you very much, I would be very grateful if you could
find me a 21A/22A set.

Morris

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TekScopes-unsubscribe@egroups.com



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