On Mar 16, 10:13�pm, "Tim Shoppa" wrote:
gbowne1 wrote:
* I'm interested in homebrewing. *I've been a SWL since 1986, and I'm
a newcomer to amateur radio, although I have been interested in that
since then too, and will be getting my ticket during the course of the
following year. *I now own a Yaesu FT-757GX which I use as my HF Gen
coverage receiver so I can still listen to SW, and practice code and
then get my ticket, while working on building the rig and slowly
learning still. *Mind you, I also have a Fluke 8050A DMM too that I
bought last year which will help me. (Still learning how to use it)

* In an effort to help me learn more about electronics than I already
know, not a whole lot at this point, I am going to build something
with which I can use once I finally get my ticket.

* In search for helpful documentation, I found a book by Randy L.
Henderson, titled
"Build Your Own Intelligent Amateur Radio Transceiver". *While now 10
years old, the book has many outdated components, and other errors in
the book. *While a good design idea, I think it could be improved on
to 2006/2007 standards in many ways.. which I will attempt to do. *The
rig is based on the 80C31 / 8051 family with a 27C64 EPROM in with a
7805 regulator, and 74LS373 on the computer board. *The computer board
also listed as having: a 1N4001, a 1N4148, a 2N2222A, a 2N2907, and
lastly a SK3444. *It also featured a 100,000uF memory backup capacitor
and a 6.2v Zener.

* My basic dimensions for the chassis are 16.1875" W x 6.1875" H x 15"
D.. so that will be the working envelope of whatever design I end up
with. *That's a pretty big space, and I like having space to work
inside.

* Well, anyhow this is my introductory post, and I'd love to hear your
comments, suggestions, etc.

My catchphrase of advice: "If you don't know how to do it, you don't
know how to do it with a computer".

I don't know much about the book in question and the radio it builds,
but the parts you name are all computer parts, not radio parts. My gut
advice would be that you not build a computer but a radio :-)

Tim, I don't want to sound demeaning about a "clever" response,
but, for the last 30 years or so, "radios" ARE using more and
more "computer" parts. The main frequency-determining
components of modern receivers, transmitters, transceivers in
amateur radio ARE "computer sub-systems." PLLs and DDSs
ARE "digital" and the last part of the "IF" in the newer receivers
ARE "digital." So is voice-frequency shaping and compression-
expansion and noise reduction.

"Begin with a simple regenerative receiver?" I say a resounding
NO to that. All that will be "learned" is assembly and how to
fuss around with trying to keep it from becoming a transmitter.
NOT a good place to start to "learn" despite the political-
correctness and "all the old-timers say that." Nonsense. I'm
one of those old-timers and "been there, done that, got lots
of T-shirts" in many ways in radio-electronics.

To "begin learning" I would suggest getting an ancient TUBE-
type "All American Five" AM BC receiver. There must be tens
or hundreds of thousands of those things sitting around unused
in attics, basements, etc. It is a basic superheterodyne
receiver with simple power supply, a local oscillator (think of it
as a "VFO-to-be"), a Mixer, a gain-controlled IF amplifier, a
diode detector, and a two-stage audio (low) power amplifier.
All the basic building blocks in there on one chassis.

EXAMINE each stage and its interrelationships, play with
changing things as clues come into mind from textbook
explanations. The "signal sources" are plentiful and no
signal generator is needed until the examination gets very
detailed. Make a mistake fussing around with one? Not a
serious problem. They can be had for nothing from neighbors
or family that accumulates old stuff...for nothing usually. Get
two or three if possible...old parts for them are getting scarce.

Need progress towards a transmitter? The Hartley oscillator
in an All-American Five is an introduction to oscillators and
modern "computer age" oscilloscopes can monitor the wave-
forms in it. One heckuva lot better than, for example, I had
it over 50 years ago. Add a simple, low-power Class C tube
amplifier (parts out of a second AM BC receiver) and one has
the basic MOPA transmitter (Master Oscillator Power
Amplifier). From there it is messing about with crystal
controlled oscillators and various keying schemes for OOK CW
and old-timer's beloved morse code. :-)

One of the VERY LAST things a beginner should avoid is to
jump in with plans to build some kind of state-of-the-art
digital transceiver. NOT from it being "made of computer parts"
but because what happens INSIDE the "digital" devices is so
enormously COMPLICATED that it can present a very steep
cliff in a learning curve about "radio." Unless one has a very
good theoretical grounding in MANY DIFFERENT circuits and
schemes that have led up to such "digital radio" designs, the
best way (to me) is to start with a KIT and learn assembling
the parts. The design has already been worked out. Those
few who bother going into WHY it woks can do so with something
that works after assembly.

Doing what "everyone else" did some 30 to 50 years ago sounds
all nice and homey but is NOT "the best" way to approach radio
in this new millennium. WE are IN the "digital age" and have been
for decades...but the analog circuits are still blended in. We
have
to know how they all interface and the characteristics of all to
make
a whole system work.

73, Len AF6AY





My feeling is that if you want to do something that is a mix of analog
and digital to do something interesting in radio, go through the SDR
("Software-Defined Radio") route. Google "software defined radio"
along with ham to see some links to stuff that's been published in QEX
and other sources the past couple of years.

But I'd encourage you to also build some really, really simple regen
receivers before doing anything that has a computer in it. The
learning curve will be so much less steep, and you'll learn so much
more about radio (as opposed to computers) by doing so.

More generically, also consider investing in the ARRL Handbook and
Horowitz and Hill's _The Art of Electronics_. Neither are abstract
academic texts, they are all about hands-on stuff. Together they will
cost more than a good used ham rig, though they will pay off much more
in the long run!

Tim.

Ok, well, with those thoughts in consideration.. I'm still a bit lost
on where to start. I know a local guy who has a SDR-1000 and I read
his blog on blogspot. Very interesting. I did all the "googling" on
it with a program called WebFerret. There is also GNUradio, and a few
other projects going on in SDR it seems.

While tubes are cool, and I am sure very nice low tube count receivers/
transmitters/transceivers could be built as they did ages ago.

Yes, I agree we live in a digital age.. and there are still many
analog circuits around. Speaking of which, from just having purchased
a copy of the 1985 ARRL Handbook today and having glanced through it.
(I like old books to begin with).

Quote: "I don't know much about the book in question and the radio it
builds,
but the parts you name are all computer parts, not radio parts. My
gut
advice would be that you not build a computer but a radio :-)"

Well, thats what I intend to do. Well, half and half. Someone has to
start somewhere.

I just wish I could rember everything my grandfather tried to teach me
at a very young age.
For reference, I'm just about to turn 30. And, I started getting into
this sort of thing around 1986.

As someone somewheres else suggested I have limited information, and
well, I just need to fill in the gaps.. not nessisarily start all
over. I barely know what to do with the probes of a DMM.. in my case
a Fluke 8050A..

Well, yes I probably could put together a kit and learn that way. In
other words, "I'm just a mentor short of a college thesis."

Oh yea, and I won't attempt to become a RF Engineer / Designer, well..
just yet anyhow. LoL.

Greg

wrote:
Tim, I don't want to sound demeaning about a "clever" response,

You might think I was trying to be cute or clever, but I really feel
the way that I wrote :-).

but, for the last 30 years or so, "radios" ARE using more and
more "computer" parts.

And I think that's fine. I personally find those parts as detracting
from what is interesting about homebrewing, up until you get to say a
Software-Defined Radio, or maybe some hamshack accessories that let
you use a computer to do clever things with your rigs.

I do feel it's pointless to build computerized gadgets when perhaps an
already existing desktop PC can do the same job. Most digital modes
beyond CW are really used much more effectively with a CRT than with
little microcontroller-based LED displays etc. Little gadgets that
turn a desktop or laptop computer from a blank screen into something
that usefully interfaces to a radio are plentiful in the ham magazines
and are fine projects.

The main frequency-determining
components of modern receivers, transmitters, transceivers in
amateur radio ARE "computer sub-systems." PLLs and DDSs
ARE "digital" and the last part of the "IF" in the newer receivers
ARE "digital." So is voice-frequency shaping and compression-
expansion and noise reduction.

Again, I tried to encourage him to go into SDR's as the cutting-edge
of homebrewing.

"Begin with a simple regenerative receiver?" I say a resounding
NO to that.

You do have a point, the OP had a pretty kick-ass all-mode SW receiver
already. Perhaps a simple rock-bound CW transmitter that could be used
once he got his ticket would be a much more interesting project.

But you do correctly deduce that my first ham-band receiver was a
regen built by me in 5th grade :-).

EXAMINE each stage and its interrelationships, play with
changing things as clues come into mind from textbook
explanations. The "signal sources" ar
One of the VERY LAST things a beginner should avoid is to
jump in with plans to build some kind of state-of-the-art
digital transceiver. NOT from it being "made of computer parts"
but because what happens INSIDE the "digital" devices is so
enormously COMPLICATED that it can present a very steep
cliff in a learning curve about "radio."

Considering that a complete working multimode multi-band (but used) HF
ham rig can be bought for not much more than what the ARRL handbook
costs new, homebrewing a complete rig is a non-starter for even those
who've been doing simpler projects for decades!

So, thinking it over again, I'd like to advise the OP to find a simple
CW QRP transmitter project that can be used with his existing receiver
after he gets his ticket.

Tim.

From: "Tim Shoppa" on 17 Mar 2007 18:10:32
-0700

wrote:

but, for the last 30 years or so, "radios" ARE using more and
more "computer" parts.

And I think that's fine. I personally find those parts as detracting
from what is interesting about homebrewing, up until you get to say a
Software-Defined Radio, or maybe some hamshack accessories that let
you use a computer to do clever things with your rigs.

To paraphrase from an old film, "we have a failure to
communicate?"

A PLL subsystem is essentially ALL digital with the exception
of the VCO itself. It uses "computer parts" and it can take
the place of a dozen or hundreds of quartz crystals, using only
one crystal as THE reference. All the parts are legacy and have
been so for at least two decades.

A DDS SOC (System On a Chip) can do the same, yet yield a much
finer frequency increment, still with quartz crystal stability
and control. It is all digital inside that SOC.

I do feel it's pointless to build computerized gadgets when perhaps an
already existing desktop PC can do the same job.

Why tie up a desktop PC to do things that can be done in a
small, dedicated assembly? A PIC microcontroller can be a
stand-alone frequency indicator...as witness to Neil Hecht's
fine products over on AADE. Or, how about a vector wattmeter
such as Larry Phipps' (N8LP) LP-100 unit that will also read
the complex impedance of the load? Or the Palstar ZM-30
antenna analyzer as a self-contained Z-R-X box to 30 MHz?
All enabled with "computer parts." All small, easy to apply
or portable with self-contained batteries.

Most digital modes
beyond CW are really used much more effectively with a CRT than with
little microcontroller-based LED displays etc.

"Effective?" Using a desktop or laptop as an I/O device, and
the internal sound card as an extra digital processor and
A/D, saves BUILDING the equivalent. But, otherwise the PC
has only a larger viewing area and color display capability.

This is the HOMEBREW newsgroup and is about BUILDING at home.

I was trying to focus on the LEARNING aspect of getting
acquainted with the various stages of radios. I picked the
ordinary old table model radio as a representative of such
a LEARNING device for several reasons: There are thousands
of them sitting around in storage, unused, replaced by
newer BC receivers; the "All-American-Five" variety has
every basic stage in it...rectifier, mixer-oscillator,
gain-controlled IF amplifier, audio voltage and output
amplifier, plus tuned circuits; it can be forgiving if one
changes some parts values to see what happens; the RF and
IF stages have frequencies low enough to view with most
modern oscilloscopes. The theory part is very legacy and
can be found in dozens of basic text books. If they are
unused for BC listening now, few will complain if a beginner
tinkers around with it.


Again, I tried to encourage him to go into SDR's as the cutting-edge
of homebrewing.

I still disagree. Someone who is only a couple steps up
from crystal detector sets jumping into Software Defined
Radios is making MANY quantum leaps in theory just to get
the PROGRAM working. That program is the heart of SDR...
once there is a processor SOC that can work with the
right frequencies...or A/Ds that work at higher IFs.

Yes, modern cell phones HAVE such things and ICs ARE available
to do RF-to-baseband software-controlled receiver functions.
Ever try to USE one of those in a lab environment? It is
NOT for beginners.

"Begin with a simple regenerative receiver?" I say a resounding
NO to that.

You do have a point, the OP had a pretty kick-ass all-mode SW receiver
already. Perhaps a simple rock-bound CW transmitter that could be used
once he got his ticket would be a much more interesting project.

Naturally using CW now that NO US amateur license requires
a code test? :-(

But you do correctly deduce that my first ham-band receiver was a
regen built by me in 5th grade :-).

It's irrelevant WHEN anyone BEGAN getting into the guts
of radios to find out how they worked. The real point
is the HOW of learning, the methods used. Everyone was
a beginner at first.

I built a SW BC regenerative back in 1947 as a teen-ager.
Out of an article in Popular Science. Outside of what
the article text gave, I didn't learn anything but how
to assemble one and solder (which I already knew from
middle-school shop class). I tried "quantum jumping" in
theory on different electronics-radio things back then
but didn't get focussed until entering the US Army and
getting into the Signal Corps. But, that is a personal
experience and isn't for everyone nor even recommended.


Considering that a complete working multimode multi-band (but used) HF
ham rig can be bought for not much more than what the ARRL handbook
costs new, homebrewing a complete rig is a non-starter for even those
who've been doing simpler projects for decades!

Sorry, but I'll say that is wrong...unless the ARRL suddenly
changed its prices for Handbooks by an order of magnitude.
"Multimode" beyond CW-only? Nah.

So, thinking it over again, I'd like to advise the OP to find a simple
CW QRP transmitter project that can be used with his existing receiver
after he gets his ticket.

It can be checked out BEFORE getting any license...using
it on the bench with a dummy load. That will allow lots
of inspection and playing around with parts values before
connecting it to an antenna. One can do the same with an
AM mode transmitter or FM mode voice transmitter (FM is the
simplest but has to be on VHF and above)...although AM DSB
is frowned upon by the "gentlemen" who occupy the HF bands.

73, Len AF6AY

This is the HOMEBREW newsgroup and is about BUILDING at home.
I was trying to focus on the LEARNING aspect of getting
acquainted with the various stages of radios. I picked the
ordinary old table model radio as a representative of such
a LEARNING device for several reasons: There are thousands
....[snip]....

And if you can find a copy of "Elements of Radio Servicing" by Marcus
and Levy, you'll learn even more! I have the 1967 version, and it
covers EVERY aspect of an AA5 down to the last details!

It also includes a little bit about transistor, auto, and FM radios.

--
--Myron A. Calhoun; W0PBV; 2001 Dunbar Road; Manhattan, KS 66502-3907
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member & Certified Instructor for Rifle, Pistol, & Home Firearm Safety
Also Certified Instructor for the Kansas Concealed-Carry Handgun (CCH) license

Interesting..

Well, I'll let you know how I go about this.

Greg