Thanks for that input; given that I am using a manual home-brew tuner (L-filter, switch configurable as either Low Pass or High Pass, and with shunt element on either input or output side of the tuner, providing great flexibility and the ability to match almost any antenna configuration) I guess the idea of putting a band switching control on the tuner doesn't trouble me all that much, but I obviously do need to take into consideration the cost of relays and filter components.
I would have to run some calculations that are probably beyond my ability as a former English Writing major to determine whether the tuner itself would provide sufficient harmonic separation or not. Probably not, since it's only a single stage of LC components. 73 Lew K6LMP On Mar 5, 2010, at 6:20 PM, Don Wilhelm wrote: > While the CCI amplifiers are indeed attractive, one needs a Low pass Filter > in addition to the basic kits. The bandswitiching of the Low Pass filters > must be controlled in some manner (not included on the kit). While it would > be feasible to create a LPF switching PIC or other intelligent device from > the K3 band data outputs, for my money, the integrated KPA3 is a better > solution. > Yes, an inexpensive solution is to just put a band switching control on the > front panel of the amplifier, but the KPA3 does that without an extra knob. > > 73, > Don W3FPR > > Lew Phelps K6LMP wrote: >> Does anyone have experience (positive or otherwise) with Communications >> Concept amplifier kits? >> I am considering an external amplifier, and these products like they >> deserves serious consideration. Reviews on eHam.net are all very positive >> (although not numerous). The circuit designs are clean and simple. And these >> kits provide a lot of "bang for the buck" in terms of dollars per watt of >> transmit power. >> >> I'm looking specifically at the company's AR313 kit, whose specs include 300 >> watts output with 10 watts input, and a frequency range from 10 mHz through >> 150 mHz. (The company informs me that the amp will function at 7 mHz, though >> with slightly reduced output because the ferrite formulation used in >> transformer coress is chosen to optimize for higher frequencies.) The >> entire amplifier (not counting a needed 28 volt 22 amp power supply) has a >> total footprint of less than 5 x 6 inches. >> The cost for a complete AR313 kit, including a heavy copper heat spreader >> and a heat sink (everything needed except a case and RF connectors) is about >> $350. Add $100 to $200 for a power supply and it's about the same cost as >> the Elecraft internal amplifier, but three times the wattage, and it will >> cover 2 meters as well as HF. It will run on as little as 13.8 VDC, but >> obviously at reduced power output (50 watts). >> >> Communications Concepts offers quite a wide range of kits, including several >> that output 140 watts on 8 watts input on 2-30 mHz, 300 watts on HF for >> under $200, ranging up to a full KW for under $1100 (all excluding power >> supplies), and two VHF amps for 2 meters at $80 and $120 in kit form for 35 >> and 75 watts output with 10 watts in. All their amps are based on designs >> created by Motorola engineers, using Motorola power transistors. For anyone >> interested, their website (sparse and last updated over a year ago) is at >> http://communication-concepts.com/default.htm. I emailed the company a week >> ago and got no response, but a phone call to them today confirmed that they >> are alive and well and living in Beavercreek, OH. >> Documentation for the AR313 kit is available at >> http://communication-concepts.com/appnotes/AR313300Sharp.pdf. >> ______________________________________________________________ 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
