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PA2AGA > HDDIG 28.07.00 13:18l 176 Lines 6207 Bytes #-9299 (0) @ EU
BID : HD_2000_201C
Read: GUEST
Subj: HamDigitalDigest 2000/201C
Path: DB0AAB<DB0SL<DB0RGB<OE5XBL<OE3XSR<OK0PPR<OK0PRG<OK0PAB<HA5OB<HA1KZH<
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Sent: 000728/0708Z @:PI8HGL.#ZH1.NLD.EU #:65347 [Den Haag] FBB $:HD_2000_201C
From: PA2AGA@PI8HGL.#ZH1.NLD.EU
To : HDDIG@EU
Date: Fri, 28 Jul 00 08:01:55 MET
Message-Id: <hd_2000_201C>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
Subject: RigBlaster
William Gourlay <cynicus@optusnet.com.au> wrote:
> He ain't a Monarchist! ...very big :-)
You got that right -- although we're a minority in Australia I'm told.
> What, is your name Dennis Leary? ;-)
:-)
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Tue, 25 Jul 2000 11:58:21 GMT
From: hamish@cloud.net.au (Hamish Moffatt VK3SB)
Subject: RigBlaster
Johnny Rico <lawdog2@ibm.net> wrote:
> Who do you mean then? All those homeless hams out there? It always
> gets me that hams will spend over $1,000 for a rig (or $2-3 thousand
> more than that for very incremental improvements offered by a fancier
> rig), ditto antennas, but then will pass up the digital modes due to a
> few hundred bucks required for a TNC or similar controller. Sure, $80
> bucks is a lot of money to some people, but frankly, it isn't much
> compared to the amount of dough most active hams spend on the hobby.
> Noise level stuff.
True. However: I doubt you could build a rig of the same quality
for that $1,000. You may or may not be able to build an antenna
for the commercial price. (You probably could, because IMHO many
mass-produced commercial antennas are overpriced.) You can certainly
build yourself a PC-radio interface for less than $80 though, and
might learn something in the process.
73,
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Tue, 25 Jul 2000 12:08:38 GMT
From: hamish@cloud.net.au (Hamish Moffatt VK3SB)
Subject: RigBlaster
Bob Lewis <rlewis@staffnet.com> wrote:
> This one is ideal for those who want to use low level constant outputs
> from the Icom accessory connector. It has an op-amp in the receive
> line to provide some gain. I use a very similar circuit between my
> IC761 and PTC-II.
I found the levels from the accessory (ACC(1)) connector
on my IC-726 to be ideal for the line in on the PC. Same
with the HF data out on my FT-847.
73,
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Tue, 25 Jul 2000 08:00:26 -0400
From: "Bob Lewis" <rlewis@staffnet.com>
Subject: RigBlaster
What I don't understand is where this "ground loop" comes from. Why
would it suddenly appear if I use a different antenna or upgrade my
computer? My understanding of a "ground loop" is that it is caused by
a difference of potential (60 Hz) between the computer ground and the
rig ground and that causes current to flow in the shield of the audio
cables. Where does this difference of potential come from if both the
computer and the rig are properly grounded to the same electrical
outlet? Any voltage drop would have to occur in the resistance of
approx 12 feet of wire (6 feet of computer power cable plus 6 feet of
rig power cable). Either the rig or the computer must have a fair
amount of leakage to the chassis.
I'm not disputing that some people have ground loops or that the
transformers help to minimize them. I wonder if the problem being so
wide spread that everyone should automatically use transformer
coupling and if so, why.
ave multiple connections and ground loops are created.
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Tue, 25 Jul 2000 12:07:07 GMT
From: hamish@cloud.net.au (Hamish Moffatt VK3SB)
Subject: RigBlaster
Rob <Pse@noemail.com> wrote:
> But optocouplers do MORE than just break up ground loops. Optocouplers also
> help isolate and PROTECT your computer from any dangerous voltages from the
> rig and vice versa due to any malfunctions, short circuits and improper
> installation. Audio isolation transformers don't do that. If you really
> want to protect your rig and computer, I contend that you should use
> optocouplers throughout NOT JUST on the PTT line.
True. But what is the chance that an audio transformer will go short
circuit between the primary and secondary? What is the chance that
the optocoupler will short between its primary and secondary? The
first risk is larger than the second, but I think they're both small.
I agree with you in principle but I think the law of diminishing
returns applies.
> I have seen posts where HAM's contend that you canot break up ground loops
> on the RS-232 line. This is not true. They can be broken up using a series
> of optocouplers and op amps. To isolate all the 25 pins in a RS-232 25 pin
> connector, the device will use quite a lot of optoisolators. But since most
> HAM applications only use 5 or so pins or lines, a simpler device can be
> used.
That is quite a lot of work. I investigated isolation for the CAT
control connection between my rig and the PC. I have a 4N25 in the PTT,
but nothing in the CAT control (which doesn't appear to be causing
any problems). Without biasing circuits you can't pass the bipolar
RS-232 signal through the optocoupler because it uses an LED and
photodiode.
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
------------------------------
Date: Tue, 25 Jul 2000 18:07:38 +0000
From: Jim Jerzycke <kq6ea@pacbell.net>
Subject: RigBlaster
No, I mostly meant young "Kid" hams, who generally have a computer long
before they get into radio. I've "Elmered" about 5 of them, and while
Mom and Dad will always spring for a computer, and usually an HT or
good, used HF rig, they may not go for a $90 accessory box.
Of course, I also strongly encourage building your own stuff when it's
that simple, and the parts are readily available. It's the best way of
learning, and a little project like this is a good place to start.
I don't have anything against RigBlaster...I think it's a nice product.
I was just commenting on the fact that not everybody can come up with
anotther $90 (plus shipping) to buy one.
73, Jim
------------------------------
Date: Tue, 25 Jul 2000 19:02:56 GMT
To be continued in digest: hd_2000_201D
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