TG501 20ns 10ns 5ns

Kerry Burns
 

Hello

I'm a newcomer to this group who has fairly recently acquired a SG503, PG506 and TG501 in a TM5003 module. All of these units are working fine, apart from the TG501 which shows some odd outputs on the 20ns, 10ns and 5ns markers. The timing seems to be correct on the slower markers (50ns and below), but the 20ns, 10ns and 5ns show as 25ns, 12.5ns and 6.25ns respectively. The 2ns is correct (can't check the 1ns, given the bandwidth of my old Tek 2465A). I've checked the markers on a second scope as well. The TG501 is a later model (Bo51xxx).

My first thought was that there must be a fault with the 20ns, 10ns and 5ns outputs - possibly in the dividers - but then wondered if perhaps the generator had been deliberately modified at some point to give the 25ns, 12.5ns and 6.25ns values. I'm not sure if this mod would be possible with the TG501? I've had a good look at the manual, but before I start delving any further I wanted to be sure it is a fault. I have checked the power supply voltages and ripple and the 1 Mhz oscillator - these are all good.

Any advice on this issue from the experts here would be appreciated.

Thank you

Kerry

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