QRZ! Ham Radio 5/QRZ Ham Radio Callsign Database - Volume 5.iso/digests/digital/940201.txt

Internet Message Format | 1994-11-13 | 9.8 KB

Date: Sun, 19 Jun 94 04:30:17 PDT
From: Ham-Digital Mailing List and Newsgroup <[e-mail]>
Errors-To: [e-mail]
Reply-To: [e-mail]
Precedence: Bulk
Subject: Ham-Digital Digest V94 #201
To: Ham-Digital


Ham-Digital Digest          Sun, 19 Jun 94       Volume 94 : Issue  201

Today's Topics:
                   AEA MBA Code Reader Input Wanted
                     finding the freq of an xtal
                       GTOR evaluation/update?
                     Ham-Digital Digest V94 #199
                     Microwave data transmission
                          SCANNER BAN COMING

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

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: 18 Jun 1994 20:07:25 -0700
From: ihnp4.ucsd.edu!usc!sol.ctr.columbia.edu!news.kei.com!hookup!news2.sprintlink.net!news.sprintlink.net!rain.org!coyote![e-mail]
Subject: AEA MBA Code Reader Input Wanted
To: [e-mail]

Recently I bought a used AEA "MBA Reader" without a manual, and would
appreciate any hints and input on how to use it.

Thus far I've been able to decode some CW and one RTTY transmission.  The
RTTY was on 20 meters, and the MBA was set at the "60" setting.

Can it also decode AMTOR/SITOR and 300 baud HF packet?  If so, how?

For CW, I don't think it works quite as well as a PK-232 I've used.

The most logical way I've found to use it, is to turn the "threshold"
adjustment untill both LEDs go out, and then find a strong signal, and
then tune the signal so both LEDs are of equal brightness.  Is this correct??

Thanks and 73 from Leigh/KM6JE.

PS:  BTW, I paid 30 bucks for the "MBA":  is this reasonable?

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Date: 18 Jun 1994 22:55:16 -0700
From: nntp.crl.com!crl3.crl.com![e-mail]
Subject: finding the freq of an xtal
To: [e-mail]

I have a xtal of unknown value (~8.7mhz) that I need to find the exact
frequency of.  What is the best way to do this?  I do have a frequency
counter, sho should I build a xtal osc and use the coutner?  How bout
a simple osc made out of cmos parts like the 4011?  If so what would
be a good schematic to use to do this?  I need to be quite accurate.

thanx,

mycal

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Date: Sat, 18 Jun 1994 13:46:19 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!csus.edu!netcom.com![e-mail]
Subject: GTOR evaluation/update?
To: [e-mail]

hamilton on BIX ([e-mail]) wrote:

: I also would be interested in hearing reports from those who've tried
: these different protocols.  But I must say, from the evidence in front
: of me, it looks like Clover, available only in the IBM PC plug-in board
: from HAL, is going to have a miserable time against a protocol available
: in a standard outboard TNC unless its technical advantages are just
: overwhelming.  Add on that the HAL board is far more expensive than
: the KAM Plus w/ GTOR and it's Marketing 101:  Clover has no possible
: chance against GTOR:  the price and configuration disadvantages of the
: HAL product make its success completely unimaginable to me.

: No surprise, if you call up any of the ham equipment stores and ask
: for a recommendation (which is really the same as asking what sells
: the most, usually) the answer is the KAM Plus, no question.

That is exactly the point.  If G-TOR is anywhere near as good as Clover
(or Pactor II, when it arrives, which will also require new hardware)
then there is little reason for anyone to migrate to Clover/PactorII.
GTOR can be a simple firmware upgrade for pretty much any multimode TNC,
at nominal cost.

There has been a fair amount of technical discussion regarding whether or
not GTOR really does deliver on the claims made by Kantronics (Don't ask
me :)   )

But would sure like to hear from actual GTOR users who have had the
chance to really determine how it compares to Amtor and Pactor.

73
--
                                             [e-mail]
                                             Glendale, CA
                                             AB6WR

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Date: 18 Jun 94 17:43:25 GMT
From: [e-mail]
Subject: Ham-Digital Digest V94 #199
To: [e-mail]

In a former treatise, Ham-Digital Mailing List and Newsgroup spake thusly:

-> Modern railays use "block control/detection" for location of trains.  This
-> system relies on the the fact that a railroad train can be a moving short
-> circuit.  This fact is detected for block detection and to signal level
-> crossings of the presence of trains.  To do this the rail system is delib-
-> erately insulated into sections.  A low voltage bridge circuit is used to
-> detect the short  between the two tracks.  The reason a bridge is used is
-> to compensate for ground leakage due to wet ties.

At road grade crossings, the track is shunted at a certain distance from the
crossing on both sides of the crossing. A constant-current low frequency
sine wave signal is fed into the track at the crossing, and the track acts
as a BIG inductor. When the train crosses the shunt, it is now a rolling
short, making the inductor smaller and smaller as the train gets closer
to the crossing. Equipment in the wayside box monitors the phase and voltage
of the track signal and computes not only how far the train is away from
the crossing, but also how fast its going. The gates always come down at
X number of seconds before the train gets to the crossing. When the train
passes the crossing, the rolling shunt is moving away now, and the box
detects this and brings the gates up immediately. The gates also come
up if the incoming shunt reduces it's speed to less than 3 miles per
hour or so.. There is an "island" around the immediate area of the
crossing where the gate will always stay down if the shunt is within the
island, regardless of speed...

To make all this work, especially where there are many road crossings
close to each other, insulated joints and various track frequencies,
as well as tuned shunts, notch filters and peak filters, .etc are used.

A radio signal wouldn't go very far in this environment..



->
-> BTW track maintenance gear has insulated wheels so that they don't trip the
-> detection circuitry.
->

-------------------------------------------------------------------------------
73 de Mike,      ax.25net:    N6KUY@W6JBT.#SOCA.CA.USA.NA
                  amprnet:    [e-mail] [44.18.0.49]
                internet :    [e-mail]
            "Old MacDonald had a farm, dit didit dit didit dahdahdah."
GCS/M { -d+ p+ c++ l u++ e+(*) m++(-) s/+ !n-(---) h-- !f g+ w+ t++ r-(--) y+ }
-------------------------------------------------------------------------------

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Date: Sun, 19 Jun 1994 10:07:29 +0000
From: ihnp4.ucsd.edu!swrinde!pipex!demon!mole.demon.co.uk![e-mail]
Subject: Microwave data transmission
To: [e-mail]

I'm looking at the possibility of using a microwave link for computer data
and voice communications between my house and a friends house. He lives
about 3/4 mile away across open fields, and we can get line-of-sight except
for a big tree right in the line, nearer to his house. (otherwise I'd maybe
use infra-red!)

Any comments?

Anyone with any experience?

Any published data?

Thanks,

Richard Smith ([e-mail])

Antique & classic Auto restorer, Agricultural engineer, shepherd,
electrician, electronics design engineer (in order of income!)

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

Date: 18 Jun 1994 17:32:38 GMT
From: ihnp4.ucsd.edu!agate!spool.mu.edu!torn!nott!cunews!freenet.carleton.ca!freenet3.scri.fsu.edu!freenet2.scri.fsu.edu![e-mail]
Subject: SCANNER BAN COMING
To: [e-mail]

Chuck Zeps ([e-mail]) wrote:
> ----------------------------------------------------------------
> From a CANADIAN PRESS article of Friday 17 June 1994
> ----------------------------------------------------------------

>          PHONE SCANNERS LIKELY TO BE BANNED

[article deleted]

> SECURITY ISSUES: " The Government is very concerned about privacy
> and security issues," said Gerrard, who attended the two-day meeting.

When are people going to realize that if you want privacy, don't use a
mode of communication that sends your conversation out into the
ether?  The cellular phone mfgrs and companies are aiding in
continuing the ignorance of the public about the lack of security of
cordless communications.  They would rather make listening illegal
than risk having to tell their customers that using a cellular or
cordless phone is like talking to your next door neighbor with a
bullhorn, or actually having to find a way to encrypt their signals to
prevent off-the-shelf receivers to listen to them.

--
Steven King           (Grid: EL89tq) | "Democracy and socialism have nothing
E-Mail        [e-mail] | in common but one word: equality. But
V-Mail          [phone] x5464 | notice the difference: while democracy
ICBM       29N 41' 26" / 82W 21' 17" | seeks equality of liberty, socialism

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End of Ham-Digital Digest V94 #201
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