EMRFD Message Archive 9227

Message	Date	From	Subject
9227	2013-10-08 18:53:09	bob_ledoux	Using 74HC04 as VFO
I'm looking at QST, 2/2005, page 32, "The W6QIF Oscillator."  The article discusses use of varicaps, and back-to-back 1N4005 diodes as tuning caps in an oscillator based on a 74HC04 inverter chip.  I'm interested in his selection of the 74HC04 chip.  He also describes his circuit as a Vackar oscillator, which suggests it is a low drift circuit.  What experience do we have in building square wave LC VFO's using such a digital chip?  I've seen numerous schematics using the inverter chip as a crystal oscillator for digital applications. Are there reasons why this application isn't more common?
9228	2013-10-08 19:59:39	Dana Myers	Re: Using 74HC04 as VFO
9229	2013-10-09 07:24:16	WA0ITP	Re: Using 74HC04 as VFO
 In his article W6QIF mentions that the TC of the -6 mix toroid he used went negative after boiling it.  Interesting, how can that happen?   ---------------------------------- Real radios weigh less than a pound. I love this radio stuff ! 72   WA0ITP www.wa0itp.com www.4sqrp.com       ----- Original Message -----
9235	2013-10-11 09:54:14	mosaicmerc	Re: Using 74HC04 as VFO
9237	2013-10-12 09:18:43	ehydra	Re: Using 74HC04 as VFO
mosaicmerc schrieb: > What do u guys think of this item: > http://www.newark.com/jsp/search/productdetail.jsp?sku=29H0701 > > That series include fast D flipflops which can give frequency division. I am thinking of making a custom oven controlled oscillator based around a 100 or 200Mhz crystal with this logic. > > Do you think 200Mhz is reasonable with this logic circuit? Yes. Maybe not over full temperature range and lowest VCC, but at 3.3V and 0 to 70°C no prob. - Henry -- ehydra.dyndns.info
9238	2013-10-12 11:39:04	Gene Dorcas	Re: Using 74HC04 as VFO
See how fast it will go and more important is it stable???  Let us know. Thanks, Gene, W5DOR