[Elecraft] Technology Change (OT)

Fri Sep 23 13:21:57 EDT 2016

I'd just like to know how an ADC works and produces some measurable form of dynamic range that I can associate with what I do know and learned about dynamic range.  I got started with Solid State Design for the Radio Amateur, published in 1977, where I learned about the concept of roofing filter but the concept didn't have a name. Wes and Doug were producing 100 db two tone dynamic range receivers in their homes, back in the day.  Then I got hold of Wes Hayward's book and learn more about how to test receivers.

I don't enjoy radio when someone seems to explain something that is so complicated mathematically that I don't understand in comparison to what I do know, or how I enjoy what I do know.  A true paradigm shift will be able to explain the new technology in terms of some mutually comparable variable that includes the old technology.

For example, I do not yet understand how Flex radio can top the chart of Sherwood's receiver table based on how two tone dynamic range is measured when I also know that Flex radio is a direct conversion radio without a way of separating the two tones of two tone dynamic range in the way that superhets do. Yes, I understand that signal separation is a delayed output based on signal sampling by the ADC but how does that process relate to two tone dynamic range?  Flex radio numbers in that chart do not make sense to me in comparison to the superhet receiver numbers that do make sense to me. 

Am I simply an  Elecraft nut when it seems by the numbers that K3 should be ranked first (based on MDS AND dynamic range), and that there needs to be some type of conversion based on two-tone dynamic range to know where the Flex-type ADC radios would rank?

Ok, so I am a nut.

73, Will wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/

--------------------------------------------
On Fri, 9/23/16, Mike Morrow <kk5f at earthlink.net> wrote:

 Subject: Re: [Elecraft] Technology Change (OT)
 To: elecraft at mailman.qth.net
 Date: Friday, September 23, 2016, 10:45 AM

 Morgan / NJ8M wrote:

 > I made a miss key ... 1625 not 1628.

 Yep...in fact there was never a 1628.  The 1625 is a
 12.6v 807, with different base.

 > ...then there was the magic EYE of the ARK 5 command
 transmitter.

 That's the 1629.  The equipment nomenclature is
 AN/ARC-5 (or ARA/ATA or SCR-274-N):
    https://en.wikipedia.org/wiki/AN/ARC-5
 The transmitters use a 1626 MO, two 1625 PA, and a 1629 cal
 indicator.

 There are many many of these sets, often in near original
 military configuration except for some capacitor
 replacement, in use *today* by those who appreciate vintage
 technology and history.  The users accept that it won't
 be K3S performance. :-)

 > ...it was great, A J38.

 The J-38 is a Morse training set key.  The J-37 was
 used with Morse communications sets.

 > I forgot my first real commercial receiver...the trusty
 BC454, with one touch
 > of the top of the case you wire 20 KHz off freq.

 The BC-454-B (3.0 to 6.0 MHz, A1/A2/A3) is not a commercial
 set, but a USAAF version from the command sets mentioned
 above...the SCR-274-N set.  If your BC-454-B drifted
 that much, something was very very wrong with it.  It
 was designed for use in all aircraft types under extreme
 mechanical vibration stress under gross temperature
 changes.  It was pilot-tuned via a long flexible
 shaft.  Its entire range was in seven inches of dial
 travel, so selectivity was deliberately very poor by
 post-war standards.

 > Then I upgraded to the BC348.

 The USAAC/AAF BC-348-* receiver (200 to 500, 1.5 to 18.0
 MHz) is basically a 1936 RCA design.  It was the finest
 aircraft radio receiver in the world during WWII.  A
 few remained in USAF service into early 1970s.

 I like the idea of a KX2 communicating effectively with a
 75-year-old BC-696-A (3.0-4.0 MHz) transmitter and
 associated BC-454-B receiver.  The latest sets like the
 KX2 and KX3 may be appreciated much more with knowledge of
 antecedent technology.  The same can be said of new and
 (likely) transient communications modes.

 To borrow from Ecclesiastes 1:4:  "One ham fad passeth
 away, and another ham fad cometh: but CW abideth for ever."

 Mike / KK5F
 [With one other old-time quirk that the modern crowd doesn't
 share:  I just can not purchase a commercial HF ham rig
 that lacks schematics.  That violates all my ham
 instincts.  :-) ]
 ______________________________________________________________
 Elecraft mailing list
 Home: http://mailman.qth.net/mailman/listinfo/elecraft
 Help: http://mailman.qth.net/mmfaq.htm
 Post: mailto:Elecraft at mailman.qth.net

 This list hosted by: http://www.qsl.net
 Please help support this email list: http://www.qsl.net/donate.html
 Message delivered to wlbaber at bellsouth.net