On the question of Scotch tape ..
I beleive it serves 2 purposes; a. to keep the formvar insulation on the
wire from being scratched
by sharp edges on a not so neatly made torroid, also to make a smoother turn
in the winding, and b.
to provide HV insulation between the core and winding.
I have built very large torroids for use here and additionally use plain old
epoxy, liberally spread
between windings and the core to increase the insulation somewhat.
On the HV spray question. An old trick from when I fixed TV sets (while in
high school, a long time ago in a place
far away ...) Remove the wiring from ordinary twinlead. Light the insulation
and carefully allow the goop to drip onto whatever you want to insulate. We
used it for flyback reapirs, worked like a charm.
Good Luck! We're all counting on you ...
ed K0KL
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of amps-request@contesting.com
Sent: Thursday, June 15, 2006 11:01 AM
To: amps@contesting.com
Subject: Amps Digest, Vol 42, Issue 40
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Today's Topics:
1. Re: glass tape scotch 27 (Mike McCarthy, W1NR)
2. FOR SALE: 3cx1500A7/8877 (Larry Emery)
3. Off Subject Urgent Need for DC Battery Booster. (Michael Baker)
4. Anyone Recognize These Components? (w2cqm@juno.com)
5. FW: glass tape ?scotch 27 (Larry Carman)
6. Re: FW: glass tape ?scotch 27 (Mike McCarthy, W1NR)
7. Re: FW: glass tape ?scotch 27 (R L Measures)
----------------------------------------------------------------------
Message: 1
Date: Wed, 14 Jun 2006 12:32:03 -0400
From: "Mike McCarthy, W1NR" <lists@w1nr.net>
Subject: Re: [Amps] glass tape scotch 27
To: <craxd1@verizon.net>, <amps@contesting.com>
Message-ID: <003401c68fd0$4ed9bd60$4cfcfc0a@LoJackOne.LoJack.com>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
It's not just the temperature, but the physical endurance and the electrical
properties as well. Remember that this stuff will be exposed to high RF and
magnetic fields. I once had the base of an RF choke in a 4-1000 amplifier
expoxied to a ceramic standoff insulator. Once night during a contest, the
epoxy exploded and coated the inside of the amp with hot yellow goo (the amp
continued to run!). So, we know through the experience of many who have
made these types of coils that Scotch 27 glass tape works as intended.
Substituting something else could cause problems like melting, a fire or
small explosion! And YES, balun coils do get quite hot when running into
high power, high SWR like the output of a tuner.
Mike, W1NR
----- Original Message -----
From: "Will Matney" <craxd1@verizon.net>
To: <amps@contesting.com>
Sent: Tuesday, June 13, 2006 2:31 PM
Subject: Re: [Amps] glass tape scotch 27
> What I'm wondering is why one would need a tape rated at 130 C (266 F)?
> The core should not get no where near that hot, maybe just warm to the
> touch which would be around 100-110 F (37.7-43.3C). Ferrite supposed to be
> non-conductive which would only leave sharp corners which can be removed
> easily with a piece of emory cloth if they have them. You can also place a
> wood dowell through the center of the toroid and use a wire brush wheel on
> a grinder to remove them very quickly from the O.D.. I generally just keep
> a piece of emory cloth on the bench and smooth them that way. It don't
> take too long to do it. I've seen many cores, both iron powder (which most
> has a painted coating), and ferrite without tape that has lasted for
> years. I wouldn't doubt that regular tape like the filament tape I
> mentioned would work just fine. Matter of fact, I know a company that used
> that tape to install the RF power meter in an amp which was mounted where
> the tubes were close, and heat actually mel
> ted the meter back when the fan quit. The tape was still ok. I cant see
> one vibrating enough to cause this either. If it does, something like the
> blower or fan is way out of balance, and ought to be replaced. The newer
> varnishes on magnet wire is pretty tough, especially if it has Teflon
> insulation like Teflon hook up wire. On toroids, you need all the space
> you can get to hold the wire if it will be a good amount, so a thin tape
> ought to be used if possible like Kapton. That is if any need be used at
> all like a good amount which does not. On input tune cores, tape means a
> lot of space where they are small. On output tank coil toroids for 80 or
> 160 meters, I've seen both taped and non-taped used. I just can't see
> where this expensive tape would be needed here for this purpose.
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR ***********
>
> On 6/13/06 at 7:14 AM tim jenkins wrote:
>
>>scotch 27 is high temp with thermosetting pressure-sensitive ashesive and
>>operates at class b 130 deg C ( 266 deg F) temp. tim kv4bk
>>scotch 27 glass cloth electrical tape
>>
>>kv4bk @ amps4u
>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>
>
>
> _______________________________________________
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>
------------------------------
Message: 2
Date: Wed, 14 Jun 2006 13:55:05 -0400
From: "Larry Emery" <k1uo@uninets.net>
Subject: [Amps] FOR SALE: 3cx1500A7/8877
To: <amps@contesting.com>
Message-ID: <000501c68fdb$ab5286c0$0900000a@FAMILYROOM>
Content-Type: text/plain; charset="iso-8859-1"
Full output, used very little. Had for spare but no longer own amp with
8877. Sell for $400
73 Larry K1UO
------------------------------
Message: 3
Date: Wed, 14 Jun 2006 23:26:56 -0700
From: "Michael Baker" <k7ddmjb@qwest.net>
Subject: [Amps] Off Subject Urgent Need for DC Battery Booster.
To: "'Arizona Ham Radio'" <azham@mailman.qth.net>,
QRP-L@mailman.qth.net, amps@contesting.com, towertalk@contesting.com
Message-ID: <000a01c69044$b3bcab60$ccdc0d82@hambone>
Content-Type: text/plain; charset="us-ascii"
Hi Gang,
I know this is a bit off subject but I have an urgent need for a
Battery Booster. This device boosts a DC input from about 10V to 13.8 and
maintains the output at that higher voltage from 10 to 13.8 volts input.
The one I am familiar with is made by a fellow in AZ at the following web
address but I don't think he can get me one BEFORE field day.
http://members.cox.net/w4rry/index.html
I am open to a used one either 23 amps or 30 amp rating.
Let me know what you might have and what you want for it. Speed is
the issue as time is short.
Thanks in advance for your collective help.
Michael Baker K7DD
k7ddmjb@qwest.net
------------------------------
Message: 4
Date: Thu, 15 Jun 2006 11:43:06 GMT
From: "w2cqm@juno.com" <w2cqm@juno.com>
Subject: [Amps] Anyone Recognize These Components?
To: amps@contesting.com
Message-ID: <20060615.044313.28262.189123@webmail52.lax.untd.com>
Content-Type: text/plain
I recently purchased an early (Pre MFJ) inoperable Ameritron AL1200
amplifier realizing full well that it was extensively modified with
components and circuit alterations that would be difficult to decipher.
Hopefully, there's someone out there that can identify the two part
component board depicted in the digital before I remove it. The PC board
appears to be professionally etched. There is no antenna changeover relay
and the large black coax wire in the foreground connects directly from the
pi-net output to the antenna output SO239. Lots of cut wires and no
recognizable method for bias control. I would cautiously assume that this is
some method of pin diode control. The amp is not functioning for a variety
of reasons so it's impossible to assess if this circuit was working or
simply a failed attempt at some modification. All the mods appears to be in
the antenna changeover circuit Any comments would be appreciated. Ron
W2CQM/3 http://Swap.qth.com/segamida/537719.jpg
________________________________________________________________________
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------------------------------
Message: 5
Date: Thu, 15 Jun 2006 10:33:46 -0500
From: "Larry Carman" <lncarman@swbell.net>
Subject: [Amps] FW: glass tape ?scotch 27
To: <amps@contesting.com>
Message-ID: <20060615153559.445D93194B0@dayton.akorn.net>
Content-Type: text/plain; charset="iso-8859-1"
Is there a HV spray ( like flyback coating ) that can be applied to toroids
that would be acceptable.
Larry N5BIP
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Peter Chadwick
Sent: Wednesday, June 14, 2006 9:37 AM
To: craxd1@verizon.net; amps@contesting.com
Subject: Re: [Amps] glass tape ?scotch 27
Will asked:
> Again, what's the use in using a tape that I would think could be replaced
with something much cheaper for us poor folks<
If you're building a one off (as so many hams do), you probably don't worry
too much about scraping around for a roll of tape if finding something
cheaper will take too long and may not do the job. It may even be the case
that there's some 'surplus' at work! In business, it's another matter, and
at a company where we used dust iron toroids in tank circuits at 100 watts
with 6146Bs, we wrapped the cores in PTFE (sorry - Teflon) plumber's tape,
which is about 0.004 inch thick, but cheap. I suspect Teflon tape would do
instead of the Scotch fibreglass stuff, assuming you can get it.
73
Peter G3RZP
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http://lists.contesting.com/mailman/listinfo/amps
------------------------------
Message: 6
Date: Thu, 15 Jun 2006 11:52:38 -0400
From: "Mike McCarthy, W1NR" <lists@w1nr.net>
Subject: Re: [Amps] FW: glass tape ?scotch 27
To: "Larry Carman" <lncarman@swbell.net>, <amps@contesting.com>
Message-ID: <000501c69093$baa64950$810ea8c0@LoJackOne.LoJack.com>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Not a spray, but I use GC Electronics Q-Dope. Of course, I wrap the core
with glass tape first. I guess you could use Q-dope directly.
Mike, W1NR
----- Original Message -----
From: "Larry Carman" <lncarman@swbell.net>
To: <amps@contesting.com>
Sent: Thursday, June 15, 2006 11:33 AM
Subject: [Amps] FW: glass tape scotch 27
Is there a HV spray ( like flyback coating ) that can be applied to toroids
that would be acceptable.
Larry N5BIP
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Peter Chadwick
Sent: Wednesday, June 14, 2006 9:37 AM
To: craxd1@verizon.net; amps@contesting.com
Subject: Re: [Amps] glass tape scotch 27
Will asked:
> Again, what's the use in using a tape that I would think could be replaced
with something much cheaper for us poor folks<
If you're building a one off (as so many hams do), you probably don't worry
too much about scraping around for a roll of tape if finding something
cheaper will take too long and may not do the job. It may even be the case
that there's some 'surplus' at work! In business, it's another matter, and
at a company where we used dust iron toroids in tank circuits at 100 watts
with 6146Bs, we wrapped the cores in PTFE (sorry - Teflon) plumber's tape,
which is about 0.004 inch thick, but cheap. I suspect Teflon tape would do
instead of the Scotch fibreglass stuff, assuming you can get it.
73
Peter G3RZP
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------------------------------
Message: 7
Date: Thu, 15 Jun 2006 08:57:32 -0700
From: R L Measures <r@somis.org>
Subject: Re: [Amps] FW: glass tape ?scotch 27
To: "Mike McCarthy, W1NR" <lists@w1nr.net>
Cc: amps@contesting.com
Message-ID: <478DA0E8-0300-4903-859C-987BF82E4990@somis.org>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Another solution is to first wrap the core with Plymouth silicone-
rubber tape, a stretchy, self-sticking, RF-compatible material that
withstands high temps.
On Jun 15, 2006, at 8:52 AM, Mike McCarthy, W1NR wrote:
> Not a spray, but I use GC Electronics Q-Dope. Of course, I wrap
> the core
> with glass tape first. I guess you could use Q-dope directly.
>
> Mike, W1NR
>
> ----- Original Message -----
> From: "Larry Carman" <lncarman@swbell.net>
> To: <amps@contesting.com>
> Sent: Thursday, June 15, 2006 11:33 AM
> Subject: [Amps] FW: glass tape scotch 27
>
>
> Is there a HV spray ( like flyback coating ) that can be applied to
> toroids
> that would be acceptable.
>
> Larry N5BIP
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-
> bounces@contesting.com] On
> Behalf Of Peter Chadwick
> Sent: Wednesday, June 14, 2006 9:37 AM
> To: craxd1@verizon.net; amps@contesting.com
> Subject: Re: [Amps] glass tape scotch 27
>
> Will asked:
>> Again, what's the use in using a tape that I would think could be
>> replaced
> with something much cheaper for us poor folks<
> If you're building a one off (as so many hams do), you probably
> don't worry
> too much about scraping around for a roll of tape if finding something
> cheaper will take too long and may not do the job. It may even be
> the case
> that there's some 'surplus' at work! In business, it's another
> matter, and
> at a company where we used dust iron toroids in tank circuits at
> 100 watts
> with 6146Bs, we wrapped the cores in PTFE (sorry - Teflon)
> plumber's tape,
> which is about 0.004 inch thick, but cheap. I suspect Teflon tape
> would do
> instead of the Scotch fibreglass stuff, assuming you can get it.
> 73
> Peter G3RZP
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
R L MEASURES, AG6K. 805-386-3734
r@somis.org
------------------------------
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