Re: tektronix 7S14 batteries and time base question


Tom Lee
 

I second Dennis's recommendation to go with Ed Breya's brilliant LED conversion method. Don't bother wasting time in search of replacement cells. Many before you have looked far and wide. Suitable substitutes simply do not exist any longer.

-- Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 12/24/2020 12:24, Dennis Tillman W7pF wrote:
Hi Rick,
How wonderful those Mercury cells were!!!
Congratulations on snagging a 5S14!!! You are going to have a ball with it. The 7S14 and 5S14 plugins are fabulous!!! Those two plugins are truly amazing and completely unrecognized for the brilliant engineering that went into them. In an instant they can turn a simple 5000 series scope capable of only a few MHz into a 1GHz Dual Trace, Dual Time Base scope capable of rock solid triggering with XT as well as XY capability.

I did an extensive search for replacement batteries about a year ago thinking it might be possible to find ones that would last long enough to be worth adding battery holders so they could be easily replaced as needed. I was very disappointed by what I found. I will be the first to admit I may have missed some possibilities so maybe you can find something I missed.
What I found:
1) Either manufacturers no longer bother to make long life cells because there is no money in manufacturing something that may never need to be replaced, or none of the current battery technologies have leakage currents low enough to prevent them from self-discharging within a few years.
2) The relatively short lifetime of any current replacement is a major problem especially when you consider how annoying it will be to remove all the screws to get to the batteries every few years.
Other factors to consider with using cells:
3) Finding cells with the right voltage that have a stable (flat) output voltage over the cells lifetime.
4) Finding cells that will fit the tight space available.
5) Figuring out how to insulate the cell holder so it doesn't touch any nearby parts of the circuit but allows for easy cell replacement every few years.

I decided that replacing the mercury cells was impractical and the only solution was LEDs. I was looking for a small enough combination of LEDs to fit in the available space (I was going to try surface mount parts next) when other responsibilities got in the way. It is something I need to get back to.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Rick
Sent: Thursday, December 24, 2020 10:10 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] tektronix 7S14 batteries and time base question

Love this thread. I am super excited for the delivery of a 5S14N this coming Monday. I assume the batteries will be too low. I'm torn between replacing the batteries and adding holders or go the LED route.

Rick






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