Re: Tek 7a13 mechanical to LED display conversion ? / 7ct1n user notes ?


Hi Rick,

The brilliant designers of the 7000 series made sure all of the slots were "generic". In other words the slot doesn't care whether you put a horizontal or vertical type plugin in it. There is nothing in the backplane that distinguishes a horizontal slot from a vertical slot and there is nothing that informs a plugin what kind of slot it is in.

By design the signals coming from the two vertical slots will go to the vertical amplifier and result in a vertical (Y axis) deflection on the CRT. The one (in a 3 wide mainframe) or two (in a four wide mainframe) horizontal slot(s) will go to the horizontal amplifier and result in a horizontal (X axis) deflection on the CRT.

In the case of the 7CT1N you can put it in any slot as long as you tell the plugin whether it was a horizontal or vertical slot that you put it in. Which type of slot (Vertical or Horizontal) you put it in requires an AMPLIFIER to go in the opposite type of slot (Horizontal or Vertical) to create the deflection on the other axis. The gain of this amplifier should be set to 50mV/Div.

There are a few timebases that have an amplifier input (7B50, 7B50A, 7B53A, 7B70, 7B80 Option 2) but the gain is not variable over a very wide range so you would be better using the 7A13 in the horizontal slot (set to 50mV/Div) and have the 7CT1N in a vertical slot.

Dennis Tillman W7PF

-----Original Message-----
From: [] On Behalf Of
Dennis Tillman W7PF
Sent: Saturday, June 09, 2018 8:14 PM
Subject: Re: [TekScopes] Tek 7a13 mechanical to LED display conversion
? / 7ct1n user notes ?


Download the 7D13 mechanical version manual and the 7D13 digital
version manual and look at the very first section of the manuals where
there is a detailed photograph with callouts that show where
everything is located on the front panel. Aside from the mechanical
readout and it's knob everything else is exactly the same and in the
same place. Vc Out is in the same place on both versions also.

Then read the section on First time use to learn how to set the 7A13
up. The only thing you might want to change is to set the + input to
DC, ground the - input, Set the bandwidth to 5MHz, set the Volts/Div
knob to 50mV/Div and un-calibrate the vertical Volts/Div. Last thing
is to connect the 7CT1N wire to the + input of the 7A13. That is all
you need except to read how to setup the 7CT1N for the particular
transistor or FET you will be testing. To test a FET you must reverse
the Drain and Gate leads as the plugin clearly shows under the banana

Dennis Tillman W7PF

-----Original Message-----
From: Sent: Saturday, June 09, 2018 7:44 PM

" ... The plug-in can still be used when the counter fails, by using
an external voltmeter to monitor the comparison voltage, Vc."

- So, on the old version, where is Vc to 'tap' into

Dennis Tillman W7PF
TekScopes Moderator

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