QRZ! Ham Radio 3/QRZ Ham Radio Callsign Database - Volume 3.iso/digests/homebrew/940052.txt

Internet Message Format | 1994-06-04 | 8KB

Date: Mon,  7 Mar 94 04:30:40 PST
From: Ham-Homebrew Mailing List and Newsgroup <[e-mail]>
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Reply-To: [e-mail]
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Subject: Ham-Homebrew Digest V94 #52
To: Ham-Homebrew


Ham-Homebrew Digest         Mon,  7 Mar 94       Volume 94 : Issue   52

Today's Topics:
                         GPS Receiver Boards
                    Help understanding FM and SSB
                          Looking for Lex...
               Need info on Toshiba TC571000D-20 EPROM
                Power FET Gate Modulation - Need Info
                     Ramsey SA-7 broadband preamp
                             Tuner-tuner

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Archives of past issues of the Ham-Homebrew Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew".

We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
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Date: 7 Mar 1994 04:47:08 GMT
From: ihnp4.ucsd.edu!sdd.hp.com!hpscit.sc.hp.com![e-mail]
Subject: GPS Receiver Boards
To: [e-mail]

The Motorola GPS receiver is less than $150 in 100's.  It has six
channels and just about all the features you would ever want.

Rick Karlquist N6RK
[e-mail]

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Date: 1 Mar 94 15:59:24 GMT
From: agate!usenet.ins.cwru.edu!howland.reston.ans.net!pipex!warwick![e-mail]
Subject: Help understanding FM and SSB
To: [e-mail]

I've read the RSGB's RAE manual, and still have difficulty with their
descriptions of FM and SSB. In FM, as I understand, the frequency of the
carrier is modulated by the amplitude of the speech. So why does the bandwidth
of the RF signal matter? If you have, say a 28Mhz carrier and the bandwidth of
the Rf signal is 5kHz, why should that limit the audio bandwidth to 5Khz? If
you send a 20kHz audio signal surely the RF signal would just oscillate
between 28Mhz+-5kHz at 20kHz? I realise that filtering the output is important
to remove any harmonics, but as you can see I'm quite confused about the
bandwidth issue.

The other thing is SSB. I get the general idea of using power more efficiently
by sending half the audio waveform as the other half is going to be a mirror
image, and removing the carrier as we want to concentrate power on the signal
instead of the carrier. What I don't get is how one removes the carrier and
then adds it back again. Can someone explain that, please?

Cheers,
Jason
--
       Jason L Saunders - President, Warwick Thrash n' Burn Society
     email: [e-mail] - PGP 2.2 key available on request
       snail: 57 Gordon Street, Earlsdon, Coventry CV1 3ET, ENGLAND
  "At least you know a sicko's committed"

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Date: 3 Mar 94 18:08:27 GMT
From: ihnp4.ucsd.edu!usc!cs.utexas.edu!convex!news.utdallas.edu!wupost!udel!news.sprintlink.net!connected.com!beauty!rwing!eskimo![e-mail]
Subject: Looking for Lex...
To: [e-mail]

In <[e-mail]>, [e-mail] wrote:
: I'm looking for a Lexical Analyzer for DOS.
: How about a 'port of "lex"?  Does anyone know where one may be found?

In my travels, I've run across at least 3 versions of Lex implemented
in C.  (And another that does Turbo Pascal.)

First, there's AT&T Lex.  You can't get the source to this.
(A version of AT&T Yacc was out, but AT&T sicced their lawyers on
people.  No bit deal, Bison and Byacc are as good or better.)

Next, there's a Lex written at University of Waterloo (by
Charles Forsythe?) that was released on a DECUS souce code tape.
It has an incompatible source languge format.  This was available as
a port to DeSmet C (a now obselete "classic" ie. Version 7 level compiler)
from the C Users Group, sold (for a while) by the Austin Code Works,
and is (I think) the lex in the MSDOS/C directory in the Simtel echos
sites C.

Finally, there's Flex.  This is a souped up Lex written at UCB that
is the most common.  It gains its performance improvement at the
expense of radically incompatible file input compared to AT&T Lex, but
as it's now the defacto standard, this is the route to take.
Available in the TXTUTL, GNUISH and DJGPP directories under MSDOS
on a Simtel echo.  Also just about every where else (Linux release,
C Users Group, Austin Code Works, and wherever comp.sources.misc is
archived ).


Mark Zenier  [e-mail]  [e-mail]

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

Date: 5 Mar 94 19:55:41 GMT
From: nprdc!ihnp4.ucsd.edu!swrinde!cs.utexas.edu!convex!darwin.sura.net!rouge![e-mail]
Subject: Need info on Toshiba TC571000D-20 EPROM
To: [e-mail]

I am working with a system that uses a TOSHIBA TC571000D-20
EPROM.  I was only able to find a National Semiconductor EPROM
chip - NM27C010Q200.  The latter is a 1 meg (128Kx8) CMOS EPROM
200 ns.  I was told that this chip would work as a substitute for
the Toshiba chip.  Can anyone verify that?  I have the pin-out for
the National Semiconductor chip. Does anyone have the pin-out / other
info for the Toshiba Chip?

Thanks in Advance.
I need to know the answer this weekend if possible.
Regards,
[e-mail]
p.s. the chips each have 32 pins.

.

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

Date: 6 Mar 1994 17:20:54 -0800
From: nntp.crl.com!crl.crl.com![e-mail]
Subject: Power FET Gate Modulation - Need Info
To: [e-mail]

 I would appreciate any information on the use of power type FETS
(Hexfet, TMOS, etc.) in AM transmitter applications.  I have some
references for this but they are rather incomplete, I am particulary
interested in gate modulation techniques to eliminate the sereis type
modulator.

Thanks

Stephen Dunifer

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Date: 5 Mar 1994 10:30:25 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!usenet.ins.cwru.edu!cleveland.Freenet.Edu![e-mail]
Subject: Ramsey SA-7 broadband preamp
To: [e-mail]

Hello.

I would like to know if any of you here on r.r.a.h have assembled
 and used the Ramsey SA-7 preamp.
I am planning to get a few of them and use them for TV and FM DX.
I will have one for FM, one for UHF, and one for VHF.
I have three seperate antennas for those bands, and seperate feed
lines too.

Will it be difficult to design a filter system where only the de
esired band(ie FM, or UHF TV) get amped by the SA-7?

I plan on buying three of them, and I would like to know what I
am getting into before I plunk down the $$$.

By the way, here are some specs:

freq range:100kHz to 1000mHz
gain:>20dB
noise figure: < 4dB
NEC microwave transistors are used in the design.
They are $14.95 each in kit form from Ramsey.
Ramsey is at: [phone]



Thanks.
--
Eric Matthews
[e-mail]

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

Date: Sat, 5 Mar 1994 15:12:05 GMT
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!convex!news.utdallas.edu!wupost!csus.edu!netcom.com![e-mail]
Subject: Tuner-tuner
To: [e-mail]

Richard McAllister ([e-mail]) wrote:
: 2. how can I build one?  [this is why this is in r.r.a.homebrew and not .misc]

You can build one for about $10 or so. It is just a variation
on a noise bridge. My 1990 ARRL Handbook has a schematic. RadioKit also
sells a noise bridge. Or you could get the MFJ noise bridge for
about $50. Set the  controls on the noise bridge to 0 reactance
and 50 ohms resistance before you tune. I built one from the
Ham Radio Magazine articles a few years ago.  It really works.

Thomas Ki4N

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End of Ham-Homebrew Digest V94 #52
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