[Premium-Rx] Comments on djvu compression format

[Ed Tanton]

Thanks Frank... both quotes are certainly as relevant today as they were 
back when!

Several years ago I bit the bullet and bought Adobe's PDF-maker (Acrobat) 
for the stuff (from my projects) I wanted to share on my website 
(specifically at: <http://www.qsl.net/n4xy/hmbw1-2.html> .) The entire 
project I mention below, as a 'book', will have PDF availability on the 
website. It is being drawn using Autosketch (AutoCAD's little brother) and 
the compression is about 90k > 20k. That's not too shabby!

Several months ago I became interested in doing a fully switchable 
front-end filter set; that included keying for an amp; as well as 
receiver-muting; using external vacuum relays for transmit (whether or not 
there's an amplifier online); and, both RF and key-down detect.

I'm really close to starting the actual work on the unit. I've gone through 
this design as I would a commercial prototype-including 
mechanical  drawings for the physical side of it, and a THOROUGH "As-Built" 
record.    The filter/preamp design has changed drastically since the 
original was PDF'd and put on the website, but it will be a composite of 
the "Active/Passive Preselector", the "BCB Rejection Filter, and the "RF 
Brick" projects. I'm thinking about turning it into a "Project management" 
magazine article, with the results being both the "As-Built" 'book' and the 
finished filter unit.

The unit provides ALL DC switching (as opposed to SIGNAL switching) of 
relays (MIL DPDT 1/2 crystal can RF relays) with BOTH BCB Reject and BCB 
bandpass filters selectable, as desired-in addition to all Ham bands 
between 160 & 10M.  The relay switching will be internal-with the exception 
of an external pair of HC-1 vacuum relays. Keying line passes through, and 
any hit on detect sets everything to a TX state (there's the capability to 
pass audio through the unit, and MUTE it or not-as desired.)

40M (only) gets a double (10 pole) set of filters simply because that's 
what I work the most. The broadband preamp will probably not be a 2N5109 
after all.. but rather  an NEC/CEL NE68133 in a design by Dr. Chris Trask: 
"Augmented Lossless Feedback Amplifier". The preamp will have a 1dB 50 ohm 
pad on both the input and output.

I started all this with a basic idea that instead of putting the relays at 
the filters, I would put them on vertical brackets; and run cables from 
them, to the filters. Then, all you have to do is wire the n/c sides of ALL 
the relays to pass-through the RF from the input. This results in a very 
nice, low VSWR. As for the internal connectors, they will all be gold SMA 
or SMC connectors. All the cables will be RG-178-sized TFE coax; and all 
the wiring TFE.

IMHO, all of this wouldn't be half as legible with DJVU as it is with PDF. 
It's that simple.


73 Ed Tanton N4XY <n4xy at earthlink.net>

Ed Tanton N4XY
189 Pioneer Trail
Marietta, GA 30068-3466

website: http://www.n4xy.com

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