Here's my initial work on a VFO for my 17 meter -- 12 Meter Single Conversion Dual Band SSB Transceiver. The IF (crystal filter) will be at 21.4772 MHz. On 12 meters the VFO will run from 3.5128 to 3.4528 MHz. On 17 the VFO will run from 3.3092 to 3.3672 MHz.
The transistor I am using is an SK3050 Dual Gate MOSFET. I bought a bunch of these years ago in a panic when I heard that 40673's were getting scarce.
I forgot to mention another important reference: Joe Carr's Popular Electronics VFO articles:
Thanks again to Dale K9NN for the bags of NP0 capacitors. And to Pete N6QW for the suggestion on the HT-37 main tuning cap. Thanks to Mike WU2D for the great VFO videos, and to Frank Harris for his wonderful book on homebrewing. And we can't forget the great reference books that guide so many of our projects: Solid State Design for the Radio Amateur and Experimental Methods in RF Design -- thanks to Wes Hayward W7ZOI and all of his co-authors.
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Where did Dale get 'bags of NPO caps?' I've been wanting to lay in a stock of NPO caps, but the usual sources (Mouser, Digikey) were very expensive, and the cheaper ones (Amazon) were rather suspect. Searching on NPO would bring me listings, but the listings themselves seemed to conveniently leave that detail out.
ReplyDeleteThanks,
-- Dave, N8SBES
Dave -- not sure where he got them. 73 Bill
Delete3.5mhz is easy to make rock stable, and for 17 & 12mhz,i was expecting higher frequency. NP0 makes VFOs easy Ed KC8SBV
ReplyDeleteEd -- no need for a higher VFO frequency, given the IF I selected. Also, I think it is always a challenge to get an LC VFO rock stable. 73 Bill
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