Re: Sick TG501 Main 1Mhz ref not running.
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Thanks Jeff,
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Michael pointed me to the appropriate section of the SM (RTFM Dave). I see there is an oscillator available on eBay. Not sure I feel the need to spend another $50 on eBay just today. I just bought an S-53 to enable viewing 1GHz signals. It was an impulse buy, sure, but this has been on my mind. And now I feel the need to have that capability. So I need to pace my spending. (Why start now!?) Another intriguing possibility I've found in the SM is the possibility of using an external clock. So it seems I could pipe the Leo Bodnar GPSDO directly into the TG501. Now there's some time mark stability and accuracy! It should be easy to add a BNC to the back of a TM50x. BTW, my homemade FR4 trimmer has set up nicely. I'm going to wait another day before trying it out on C515. I am looking forward to using it on the 2ns and 1ns Filter caps. I feel I've already tuned them well, but this all seems to require repeated fine tuning. And hopefully with the S-53 I'll be able to observe the 1ns signal at full BW (this will go in a 7S12 with S-6 sampler which is working quite well with my now working S-52). Dave On Friday, December 3, 2021, 03:21:58 PM PST, Jeff Dutky <jeff.dutky@...> wrote:
Dave, I had thought that I had seen a video by either Jared Cabot (NFM) or Zen (Zenwizard) showing the addition of Option 01 to a TG 501, but I can't seem to find it now. I may have been thinking of Jared's video about adding a similar option to a DC503A. The TG 501 Option 01 seems to consist of basically two components: U50 (a 7490 TTL decade counter) and Y50 (a 5MHz crystal oscillator, possibly ovenized?). The part numbers for Y50 are either Electronic Research Co. EROS-600-TK-9 (SN below B034510) or Bliley Electric Co. T15B141 (SN B034510 and above). I imagine that any 5 MHz TXCO or OCXO can be made to work, with effort. The service manual has this to say about Option 1: The TG 501 Option 01 is equipped with a temperature-compensated, 5 MHz crystal oscillator for a highly stable and precise internal clock. U50 provides countdown circuitry for the 5 MHz crystal. Remove U100 and disconnect pin 3 of U350 before using external clocks. To disconnect pin 3 remove U350, bend pin 3 out then insert U350 back in tcurciut board. The main circuit board jumpers that must be installed for Option 01 are: J3 and J7 (see. Fig. 5-2 for jumper location). -- Jeff Dutky |
Dave Peterson