simple frequecny multiplier

well i managed to detemine what frequency i have by looking at the frequency coming out of the mixer. ie i set the inputs to 40Mhz and 40.0001Mhz and i get out a strong 1khz so its working at x10. you can also clearly see the sub harmonics when it is out of tune on the scope. they disapear as far as i can see on the scope when I tune it wich will suit my purpose.

wel i did come accross this ...

good luck. :D

Thanks for the tips :D

I know multipliying crystal frequencies has often been done by radio enthusiasts, theres lots of quite detailed information for low frequency ones of course, and the project in the above link uses a srd for one as someone also sugested, however i get adequate results from my single bf998 (biased low) with input stage tuned at 200mhz driven from the 40mhz xo and an output stage tuned at 400 mhz, (tranmsmision line driven from a tap) bf998 definatly my fav transistor these days. Also the input to the mixer is tuned to 400mhz.

I stuck to 400mhz in the end (wich like the example you gave is x5,x2), as im using a sa602a mixer atm wich probaly will give diminishing returns if I go any higher, also the inductors for tuning the input to this are almost down to a single turn.

Colin =^.^=

In message , John Larkin writes

Google "Allens Time" for a spread sheet to convert SSB noise to jitter. You must consider noise floor, best with SAW resonators and close in noise best with crystals (which cant be driven as hard as SAWs). SC cut crystals are much less sensitive to thermal transient (true thermal fluctuation) Still got some surplus 16.384 MHz SC cut OXCOs

Thanks, ive just got some surplus ocxos on delivery from ebay, ive given the idea of a pll some thought and as the only reason is to get beter signal strength from a phase detector a pll with pd operating at the un multiplied frequency will defeat the object.

Also although a x25 multiplier will multiply the noise bandwidth by 25 it will also multiply the output by 25 too so no loss here unless the multiplier adds its own noise but its a low noise stage operating at high signal so unlikly.

maybe the best solution would be to pass the multiplied signal through the saw filter.

Incidently, is low frequency capacitor noise an issue with tantalum capacitors, ie leakage current fluctiations ? particularly in a

In message , colin writes

The best source for all information on capacitor noise/distortion is Cyril Bateman, his articles in electronics world uk reach conclusions and tell you how to measure. Primarily as a means of demonstrating whats best for audio but none the worse for that!