Re: 184 Time Mark Gen. - 2nS & 5nS not working


Tom Gardner
 

ISTR I improved my 500MHz oscillator's output by modifying the coupling in the L69/L70 transformer.

Yup, I pushed the L70 wire so the two halves of the transformer were closer together :)

I also kept in mind that the purpose is to provide timing accuracy, not amplitude accuracy. Sometimes life is too short.

Oh, I did buy a NOS nuvistor for around £10.

On 03/04/20 21:24, Dave Seiter wrote:
I've had three 184s over the years, and I've never had one in which the 2 and 5nS sections worked correctly.  I gave up trying to fix the last one.  Maybe if you get some good leads I'll give mine another go (since I have so much time on my hands anyway!)
-Dave
On Friday, April 3, 2020, 01:06:15 PM PDT, david via groups.io <davide_us=yahoo.com@groups.io> wrote:
Only issue I have left to fix is the 5nS sine output is only 88mVpp. should be minimum of 0.3Vpp, and the 2nS sine output is not working at all. Have 100Mhz  3.7Vpp at input to 2nS board, no output. Have 2Vpp 100Mhz at input to 5nS board, only 88mVpp @ 50 ohm 200Mhz at output. Can any one help? I am wondering if either of the tubes V60 or V70 on 2nS board could be bad. Is there any way to check?  Is it possible that the 5nS output is only 88mV because of the low input of only 2Vpp ? Could the forward voltage drop on the diodes of the doubler  be that much?

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