Newbie: question about old shortwave converter schematics
 

I'm new to shortwave, so if I sound like an idiot, it's because I am... :)
Anyway,
I found a schematic/howto to build a SW converter for car radio. From the
looks of it, it was done sometime in the very early 90's. It includes a
10.7 MHz IF transformer, and a NE602.
One of the parts listed is a ".047 æF" cap, and although my electronics
knowledge is decent, one of the holes in it is what the "æ" represents.
(Yeah, I know uF is microfarad, nF is nanofarad, pF is picofarad, etc. Just
never ran across something with the æ before.)
From what I scraped together with Google, it's the same as a 47 pF. Thought
I'd check with experts to be sure, though. :)

To avoid confusion since there are a few of these schematics floating
around, this is the author's info from the public domain statement included
with the other files I am using:

-------------------------------------------------

M. Cooper
3425 Chestnut Ridge R.
Grantsville, MD 21536-9801
-------------------------------
Email:

-------------------------------------------------

(The email comes back nonworking)
Thanks in advance for any help!
- Rick

I just found the schematic you must be looking at, at
http://dnausers.d-n-a.net/prepared/gear/convert.txt

It appears that C4 is simply a bypass capacitor to get rid of any noise
generated by the zener D1. I would use .047 microfarads.

My guess is that the originator was trying to be cute and generate the greek
letter "mu" for the traditional abbreviation of microfarad, but screwed up
and generated "ae" instead.

--Chuck N7RHU




"Rick Andrews" wrote in message
...
I'm new to shortwave, so if I sound like an idiot, it's because I am... :)
Anyway,
I found a schematic/howto to build a SW converter for car radio. From the
looks of it, it was done sometime in the very early 90's. It includes a
10.7 MHz IF transformer, and a NE602.
One of the parts listed is a ".047 æF" cap, and although my electronics
knowledge is decent, one of the holes in it is what the "æ" represents.
(Yeah, I know uF is microfarad, nF is nanofarad, pF is picofarad, etc.
Just
never ran across something with the æ before.)
From what I scraped together with Google, it's the same as a 47 pF.
Thought
I'd check with experts to be sure, though. :)

To avoid confusion since there are a few of these schematics floating
around, this is the author's info from the public domain statement
included
with the other files I am using:

-------------------------------------------------

M. Cooper
3425 Chestnut Ridge R.
Grantsville, MD 21536-9801
-------------------------------
Email:

-------------------------------------------------

(The email comes back nonworking)
Thanks in advance for any help!
- Rick

On Sat, 13 Dec 2003 02:26:35 GMT, "Chuck"
wrote:

My guess is that the originator was trying to be cute and generate the greek
letter "mu" for the traditional abbreviation of microfarad, but screwed up
and generated "ae" instead.

From the early '90s, it's probably a DOS document. If you cut the
"ae", paste it in Notepad, save the file, get to a DOS prompt, and
open with Edit, you'll see "mu". Just a different character set.

- Bob

The StickWorks
http://www.stickworks.com

Rick Andrews wrote:
[snip]
One of the parts listed is a ".047 æF" cap, and although
my electronics knowledge is decent, one of the holes in
it is what the "æ" represents. (Yeah, I know uF is
microfarad, nF is nanofarad, pF is picofarad, etc. Just
never ran across something with the æ before.)
From what I scraped together with Google, it's the same
as a 47 pF. Thought I'd check with experts to be sure,
though. :)
[snip]
I suspect that it's a font confusion and represents microfarad. We substitute the Greek character "mu" that stands for "micro" with "u" in the Latin alphabet when the character set does not support the correct representation of "mu". "MicroFarad" should look like this, "mF", if the font is preserved in this message. I have no explanation why it would come out as "æ".

Tom

I just discovered that if you view the text and schematic using MS Linedraw
font, the "ae" becomes a greek "mu" .

--Chuck


"Rick Andrews" wrote in message
...
I'm new to shortwave, so if I sound like an idiot, it's because I am... :)
Anyway,
I found a schematic/howto to build a SW converter for car radio. From the
looks of it, it was done sometime in the very early 90's. It includes a
10.7 MHz IF transformer, and a NE602.
One of the parts listed is a ".047 æF" cap, and although my electronics
knowledge is decent, one of the holes in it is what the "æ" represents.
(Yeah, I know uF is microfarad, nF is nanofarad, pF is picofarad, etc.
Just
never ran across something with the æ before.)
From what I scraped together with Google, it's the same as a 47 pF.
Thought
I'd check with experts to be sure, though. :)

To avoid confusion since there are a few of these schematics floating
around, this is the author's info from the public domain statement
included
with the other files I am using:

-------------------------------------------------

M. Cooper
3425 Chestnut Ridge R.
Grantsville, MD 21536-9801
-------------------------------
Email:

-------------------------------------------------

(The email comes back nonworking)
Thanks in advance for any help!
- Rick

Thanks for your help, guys!


(On a separate note, someone (who will remain nameless) emailed me offlist
and basically ripped me up for "doing this on the cheap" instead of
dropping several hundred dollars on Sony or Grundig kit.

I believe that building it myself is half the fun, so nyah!

Speaking of which, since the car radio I'm using has analog tuning, what's
the expert opinion on using a good stepper motor and an RS-232 interface to
control tuning with a PC?
I thought it'd be nice to have infinite presets, and maybe even a relay
controller for switching crystals. But again, I thought I'd check here
first.

-Rick

Your stepper motor tuning loop would have to be closed on the received
signal strength for it to be of any use in an analog tuning system. Simply
driving the motor open loop to a preset dial position may not be repeatable
enough. Also, the stepper drive system would have to have sufficient
resolution for it to be able to correct for drift with this closed-loop
approach. That is the big advantage of the PLL over a manual tuner.


"Rick Andrews" wrote in message
...
...
Speaking of which, since the car radio I'm using has analog tuning, what's
the expert opinion on using a good stepper motor and an RS-232 interface
to
control tuning with a PC?
I thought it'd be nice to have infinite presets, and maybe even a relay
controller for switching crystals. But again, I thought I'd check here
first.

-Rick