A few days back I inquired of the list if anyone knew of a small post-amp that would prefilter the XG3 square wave and give it about 30 dB boost. There were no answers. The problem seems to be that most QRP or QRPp amps already require a few tenths of a watt input, and the 1 mW from the XG3 is just too tiny...
I have been specifically thinking about using the XG3 (in its spare time) as a 6 meter beacon. Just hooking it up to a "resonant" antenna is not (IMHO) legal, since antennas (think center-fed half wave doublets) do not discriminate against ODD harmonics. FCC requires better...see ยง97.307 Emission standards, section (e). I have been thinking this over, and it looks like the best answer is to build around a 20 dB gain block running in to a power module, such as the MAR-6 gain block into a M57735 power module. The output from the XG3 would need to be low-passed before the gain block, since the usual gain blocks are quite wide band (e.g. DC-3 GHz, etc.). HOWEVER, a glance at the manual for the XV series transverters already shows a transmit path designed and ready, in the schematic for the XV50. Aside from ~dozen SMD caps in the filtering (not needed!) connecting the mixer to the SGA7489 gain block, the needed component list is rather short, about 26 parts, most of which are mundane. I asked Wayne if Elecraft would bag up these parts and sell them to me as a partial kit, and his response was more or less positive, but he requested that I poll the list to see if there is any other interest: -----> A partial kit, no enclosure or circuit board, to assemble a 6 meter post-amp for the XG3 that would produce 1-5 watts. <----- Note: the SGA7489 gain block is obsolete but the device remains in the supply chain. Note: the RA30H0608M power module is designed to put out 30 watts in the 68-88 MHz range. To drive it to this power level from the XG3 might require cascading two gain blocks. A substitute part is the M57735 mentioned above, designed for 25 watts at 50-54 MHz. I think that a post amp built "ugly style" around these ideas would fit into an Altoids tin. The only hitch is proper heat-sinking of the power module. The layout used for the XV50 takes care of the biasing. ***** So, I am asking the list: "Is there any interest out there amongst XG3 owners in having Elecraft bag up a partial kit as outlined above?" ***** This note is also going directly to Eric at Elecraft, who holds the reins for manufacturing... John Ragle -- W1ZI P.S. The schematics for the XV50 is included in my manuals for my XV144, which BTW works wonderfully... ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
