What load do you have it running into? It maybe that you need to load it into 50 ohms.
Steve On 23 June 2010 16:54, Leigh L. Klotz, Jr WA5ZNU <le...@wa5znu.org> wrote: > At the local flea market, I picked up what appears to be an Efratom FRS-C. > It is marked "TTL" internally. It has the passive connector board, but not > the active board with the 15 MHz synthesizer on it. > > Mine is marked "TTL" internally. The service manual has a chart showing the > differences between the sine and TTL options, and I converted it to the sine > version by changing a jumper to a resistor and populating an LC filter with > 10uH and 100pF (~5 MHz). I also terminated the RF connection on the > connector board with a 47 ohm resistor to ground. > > The output now doesn't have the tremendous overshoot it used to have, but > it's also not very sinusoidal. That's not surprising given the simplicity > of the on-board filter. > > Instead of a multi-stage LC filter, I wondered about a crystal ladder > filter: since the output frequency is fixed, the high Q and low cost of the > crystal filter might be an advantage, but I wasn't sure about how effective > xtal ladder filters are at suppressing harmonics, as each individual > crystals would have odd overtone responses, so it might not be a good plan. > > Does anyone have practical experience with a filter topology for cleaning up > the output of the FRS-C at 10 MHz? > > Leigh. > > P.S. Just so that I can be topical, note that the FRS-C has a C-field > adjustment 0-5V input, so I could use it as the reference oscillator for a > TPLL. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Steve Rooke - ZL3TUV & G8KVD The only reason for time is so that everything doesn't happen at once. - Einstein _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.