On Sat, 16 Apr 2011 07:07:25 -0700 (PDT), you wrote: The K3EXREF will use either a sine wave input at 4 to 16 dBm (2 to 3.3V), or a TTL signal. The manual advises using a 50 ohm series resistor for 5V TTL to drop the voltage level into the proper range. >1. Will the K3EXREF work straight from the output of an Efratom LPRO-101 or >does it need a TTL square wave output or something else requiring extra >circuitry between the LPRO and the K3? > Yes. In this case, the K3 reverts to the stored REF CAL value. The way I've set this up is to let the K3 make the compensation approach a final value by running for a few hours on the external reference, then programming the REF CAL shown while on the ref into the CONFIG menu parameter. Testing later shows this produces precision of a few Hz, even with a 5C of temperature change, at 50 MHz and using the 5 PPM TCXO in the K3. >2. If the K3EXREF is installed, will the K3 still work as normal if the >frequency standard is not turned on? To maximize life of the rubidium lamp >in the frequency standard I wouldn't want to leave it on all the time and >for a lot of amateur operation the frequency accuracy it provides isn't >needed anyway. > Another good choice is the Trimble Thunderbolt receiver. There are a lot of these refurbished units available on eBay or elsewhere for under $100. You can leave this receiver on full-time if necessary (I do). The Thunderbolt outputs a sine wave at 12.5 dBm.
I used an Rb standard borrowed from work for a few days, and found that the Thunderbolt and Rb produced about the same amount of precision. The Rb is noisier though (in the time domain), looking at its output on a spectrum analyzer. You can't beat an OCXO for cleanliness.... 73, Matt W6NIA =.= >Julian, G4ILO > >----- >Julian, G4ILO. K2 #392 K3 #222. >* G4ILO's Shack - http://www.g4ilo.com >* KComm - http://www.g4ilo.com/kcomm.html >* KTune - http://www.g4ilo.com/ktune.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
