I picked up an HP 8656B from the usual place and have been cleaning it up... got around to testing the output which looks good on a cheap frequency counter etc...
I'm wanting to use the 10 MHz output from my TBolt for the reference input on the HP 8656B and my Elecraft K3. So I started digging around in the manuals I can find on the internet, including KO4BB's cool manual stash. I'm not finding the specs on the input for the reference on the 8656B. I found an older reference for the 8646A that said to keep the input rms voltage between .2 and .4 volts, which scared me, because I had already hooked up the Tbolt direct. If this is correct, then .2 vrms - .4 vrms is around +2 dbm. The direct output on the TBolt to my scope is showing ~1.7 vrms which is close to +17 dbm. Yikes, I had that hooked up to the 8656B for a while... I hope I didn't screw anything up. I have a K3 with the EXREF board hooked up direct to the TBolt and it's happy as a clam with the 1.7 vrms input. Which is a tad bit high for the Elecraft docs which shows a nominal level of +4 dBm to +16 dBm. I'm assuming the 1.7 vrms is falling in to the 'nominal' range. I'm not finding dire warnings about hooking the TBolt 10 MHz output direct to a K3EXREF or an HP FG... I don't have a frequency counter that takes an external reference (yet), so it's hard to know if the HP 8656B is using the external reference. Again, I can't find much in the manuals to validate the external input, other than using a FC with the same reference input. Any input or tutoring would be helpful. Are others just adding resistance in line with the TBolt output to drop voltage? I tried a 50 ohm resistor and it dropped from 1.7 to just under 1v rms on the scope. Thanks Max NG7M -- M. George _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
