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ZL3AI > APRDIG 01.12.03 11:37l 218 Lines 9032 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Nov 27, 1/1
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Thursday, November 27, 2003.
1. Re: ICOM IC-2AT info?
2. Re: Fusing the ground lead...
3. Re: Fusing the ground lead...
4. Re: Fusing the ground lead...
5. APRS Talks at the TAMPA Hamfest
6. Re: Great Post
----------------------------------------------------------------------
Subject: Re: ICOM IC-2AT info?
From: "Richard Amirault" <ramirault@erols.com>
Date: Thu, 27 Nov 2003 01:40:16 -0500
X-Message-Number: 1
>So....if I understand this correct. Do not connect 12volts to the radio
>where the battery connects to the radio. I was thinking about setting up a
>tracker this way with the RS HTX 202. So what would be the highest voltage
>regulator I could use?
>
>I found a clip with wire leads that replaces the battery.
The HTX-202 has a seperate 12v jack on the top of the radio, just to power
the radio (not to charge the battery) No need to remove the battery pack to
feed power to the radio.
Richard Amirault N1JDU Boston,
MA, USA
www.erols.com/ramirault "Go Fly A Kite"
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Subject: Re: Fusing the ground lead...
From: Wes Johnston <wes@johnston.net>
Date: Thu, 27 Nov 2003 08:55:25 -0500
X-Message-Number: 2
What taught me the lesson was that my 2m radio lost it's ground (antenna
was mounted to a tool box in the bed of truck and was not grounded to
truck). When the TNC keyed up to TX, the radio sought a ground thru the
TNC. If the negative lead on the TNC had been fused with 100ma, I wouldn't
have cooked the PCB. After fixing that, it occurred to me that the same
could happen to the radio if the starter were to loose it's ground..
So, moral of the story... if you wire directly to the battery, use two
fuses. If you ground to the chassis of your car, you can use one fuse.
Wes
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Subject: Re: Fusing the ground lead...
From: "Mike Yetsko" <myetsko@insydesw.com>
Date: Thu, 27 Nov 2003 09:20:12 -0500
X-Message-Number: 3
From: "Wes Johnston" <wes@johnston.net>
>What taught me the lesson was that my 2m radio lost it's ground (antenna
>was mounted to a tool box in the bed of truck and was not grounded to
>truck). When the TNC keyed up to TX, the radio sought a ground thru the
>TNC. If the negative lead on the TNC had been fused with 100ma, I
wouldn't
>have cooked the PCB. After fixing that, it occurred to me that the same
>could happen to the radio if the starter were to loose it's ground..
>
>So, moral of the story... if you wire directly to the battery, use two
>fuses. If you ground to the chassis of your car, you can use one fuse.
>
>Wes
And that's how it should be! Well, also considering what may happen if you
have something like 'detachable beds' that may have ground issues, of
course. In your case, I think I would have capacitively coupled the
antenna at the mount, not DC grounded.
But I find it hard to understand why people would attach to the battery in
a vehicle. The vehicle is a complete 'system'. Attaching to the battery
for (-) makes sense when the battery is independent, but in a vehicle, the
body will interact with your radio anyway, so attaching to the battery for
(-) is like attaching somewhere OTHER than ground.
I have to wonder... What's the I2R losses on TX through a (-) lead fuse? I
wonder if it's higher than you'd get on a battery to chassis connection? (A
PROPER battery to chassis connection! If it ain't a good one, then it's
broke. FIX IT!) If so, then it's poor amateur practice anyway!
Also, I hear people complain they are doing it to solve alternator whine.
Excuse me? If you have alternator whine, FIX THE PROBLEM!! You might even
save yourself a more extensive repair or a stranding later on anyway.
----------------------------------------------------------------------
Subject: Re: Fusing the ground lead...
From: Floyd Rodgers <kc5qbc@swbell.net>
Date: Thu, 27 Nov 2003 10:09:13 -0600
X-Message-Number: 4
I use the double fuse method and go straight to the battery for several
reasons. I get less noise on the supply lines to the radio, and I know it's
as good a ground as I can get. You can never tell what part of the vehicle
may be picking up the engine/pump noise because of a less than perfect
ground contact. It does make a difference if you try to operate HF mobile.
Floyd Rodgers KC5QBC
Multi ended candle burning artist in training
----------------------------------------------------------------------
Subject: APRS Talks at the TAMPA Hamfest
From: Bob Bruninga <bruninga@usna.edu>
Date: Thu, 27 Nov 2003 15:39:02 -0500 (EST)
X-Message-Number: 5
>On Thu, 20 Nov 2003, Will Holcomb wrote about TAMPA Hamfest:
>
>>SATURDAY DECEMBER 6th,2003
>>12:00 PM "Optimizing the APRS Network" by WB4APR
>> 3:00 PM APRS Users Group- With Guest WB4APR
>>
>>SUNDAY DECEMBER 7, 2003
>>11:00 AM SPECIAL GUEST-WB4APR's other Hot Topics"
----------------------------------------------------------------------
Subject: Re: Great Post
From: "John Langtry, VE3NEC" <ve3nec@sympatico.ca>
Date: Thu, 27 Nov 2003 22:02:42 -0500
X-Message-Number: 6
Hi Dave & all.
Thank you for your e-mail on the fusing issue. Many years ago, I purchased
a new (Icom, in my case) radio, and I wondered what the heck was in the
minds of the engineers at Icom to fuse both leads. I now know why !
Wes and Mike have also posted very interesting thoughts as well; which I
appreciate, fellows.
As a rule, I try to keep off the SIG any specific N.A. vehicle maker by
name. On the other hand, I'm a bit of a "car & motorcyle nut" and I live in
a small town, N.W. of Toronto. And as an Amateur, as well as the aforesaid,
"nut", from time to time, I get "requests" for help with a technical /
electrical problem.
One chap, bought a "toy car" (Stan, keep calm) a G.M. Trans-Am, one of the
last, as I believe that the plant in Quebec is now closed, and those V-8
RWD toys (saddly) have passed off into history this past model year.
Well, this chap had an intermittent problem with his car; as Amateurs don't
we all just *love* intermittents ? :)
From time to time, no temperature relationship, nor time that the vehicle
was being used; his gauges would go "nuts". (He'd be doing, say 60 Km/Hr
(30M/H) and both his tach and speedometer would "pin" ... ditto all other
analogue displays.)
GM Canada, and his dealership, tried "everything", changed sensors, changed
engine controller computer, but still from time to time, his gauage-cluster
would go "nuts". Finally, the cluster failed, and out of utter despiration
brought his "toy" over to our local Dodge/Chryster delearship, for a second
opinion. (At his expense.) And they came up with nothing, but said "Hey, we
know this Mopar nut (me) - many he can figure this one out, because we
can't." (By now, Stan is definately grining his teeth; Stay with me Stan,
becuase this does have an on topic item.)
So, at my office, (I work for the Telephone company), I get this call for a
"consultation". Why me ? I've never had a G.M. machine in my life time, I
used to have Fords, and for the last 20 years, Mopars. "Well, this one is
really weird, it's "electical" and we're asking you to just have a look."
(I'm a sucker for a challenge.)
Okay, so, I asked them to get the drawings (service manual) from the G.M.
delearship; and when I have a minute, I'll have a look at it. (By now, the
owner of the "toy" was champing at his bit.) So I did the usual, "look for
the obvious".
Long story made shorter, before Stan boots me off the SIG, was that G.M.
showed in their drawings, a second ground, a braided strap between a bolt
on the engine block, and a bolt, on the fire wall. Both bolts were present,
but no ground strap ! $ 5 later, and a couple of minutes for one of tech's
to install it; problem gone !
He had, of course to pay for the shop time at the Dodge dealership, and the
cost of the missing ground strap. My fee ? "If you go over to our local
hosptial and give them a $ 250 donation, and show me your receipt, we're
even."
(If you think the test sets used in our hobby are expensive, you should see
the costs of medical instruments !!!")
He is "delighted" with his machine to this day, and was more than happy to
donate some funds to our hospital.
So my point in all of this ? No matter where you pick up your ground,
battery terminals or vehicle's chassis, *please* fuse the negative side of
your connections, as well as your power source - because you never know -
better a 50 cent fuse, than a blown radio or burned out TNC !
I could tell you about the lady with the new Chrysler 300M, who had a
"tweat" that no one could find; to the point where here husband was just
about ready to have her "committed" ... If you want to know about that -
e-mail me off line, because, I think I've pushed Stan's patience to the
limit !
Vy 73 to all, de John VE3NEC
905-873-8715
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