Vacuum vessel-pressure cooker?
Wayne kd7rur
Woodland WA
On Monday, October 3, 2016 10:10 AM, "amps-request@contesting.com"
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Today's Topics:
1. Re: Amps Digest, Vol 166, Issue 1 (monk)
2. Re: Buzzing Transformer Follow-up Questions (Bill Turner)
3. Re: MFJ-(AMERITRON) ROLLER INDUCTOR? (Bill Turner)
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Message: 1
Date: Sat, 1 Oct 2016 16:36:34 +0000 (UTC)
From: monk <monk36098674@yahoo.com>
To: "amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps] Amps Digest, Vol 166, Issue 1
Message-ID: <1804671234.7906777.1475339794782@mail.yahoo.com>
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Transformer Buzzing
? Hi,
? I don't know if the transformer is already varnished or if the I E plates are
bare metal. I read somewhere that if the plates are bare metal you can use the
thin super glue and it will quiet down the transformer.
????????????????????????????????????????????????????????
Wayne???????????????????????????????????????????????????????? kd7rur
Woodland WA
On Saturday, October 1, 2016 9:27 AM, "amps-request@contesting.com"
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Today's Topics:
? 1. Re: Buzzing transformer (Jeff AC0C)
? 2. Re: Buzzing transformer (Gary Smith)
? 3. Re: Buzzing transformer (Roger)
? 4. Re: Buzzing transformer (Steve Wright)
? 5. Ameritron/MFJ ROLLER INDUCTOR for GS35b amp (nemo zilch)
? 6. Re: MFJ-(AMERITRON) ROLLER INDUCTOR? (Tom Osborne)
----------------------------------------------------------------------
Message: 1
Date: Thu, 29 Sep 2016 15:53:47 -0500
From: "Jeff AC0C" <keepwalking188@ac0c.com>
To: "Steve Wright" <stevewrightnz@gmail.com>,??? <amps@contesting.com>
Subject: Re: [Amps] Buzzing transformer
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My PA76 buzzes a bit.? But I had another PA76 transformer from a guy who
swapped it for a Dahl and that one sung like crazy.? Used it for a ton of
key down power tests on an amp I was building and it never showed any other
side effect than rattling.
On the other hand I have had a diode and a couple of filter caps go out in
my PA76.? So you may want to check those for good measure as well.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message-----
From: Steve Wright
Sent: Thursday, September 29, 2016 2:56 PM
To: amps@contesting.com
Subject: Re: [Amps] Buzzing transformer
On 30/09/16 05:00, David G4FTC <g4ftc@hotmail.com> wrote:
>> Hi Steve,
>>
>>
>> I agree that any transformer can have a winding replaced, but would it be
>> cost effective, particularly with a small transformer? It would probably
>> be
>> cheaper to buy a new unit.
Just have a go at it.
S
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Message: 2
Date: Thu, 29 Sep 2016 17:36:43 -0400
From: "Gary Smith" <Gary@ka1j.com>
To: Amps@contesting.com
Subject: Re: [Amps] Buzzing transformer
Message-ID: <57ED896B.124.6A6C1F1@Gary.ka1j.com>
Content-Type: text/plain; charset=US-ASCII
> If the transformer runs at its normal temperature, then it is probably
> just a loose lamination - not usually a problem, just annoying.
I remember having a transformer buzz due
to loose laminations. I mentioned it to a
friend who did castings at work and he
said to bring it by. They had a vacuum jar?
large enough to put it in. We slathered it
with glue ( I can't recall which glue it
was, it was not viscous ). He put the
transformer inside the jar and sucked the
air out while it was covered with the wet
glue.
It bubbled for a bit while the air was
being sucked out of the
laminations/windings. When the bubbling
stopped he released the suction and the
glue was instantly sucked into the
laminations where the air pockets had
been.
a couple days later the transformer was
dry & sealed up internally by that glue,
and that buzz was completely gone.
73,
Gary
KA1J
------------------------------
Message: 3
Date: Thu, 29 Sep 2016 14:48:27 -0700
From: Roger <ai7rogerroger@gmail.com>
To: amps@contesting.com
Subject: Re: [Amps] Buzzing transformer
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Provided the windings are good, I'm wondering if it wouldn't be possible to
rebake the transformer or even apply an additional coating of sealant and
rebake to see if it would reseal the pieces parts?
73, Roger
W7TZ
CN83ia
On Thu, Sep 29, 2016 at 12:56 PM, Steve Wright <stevewrightnz@gmail.com>
wrote:
> On 30/09/16 05:00, David G4FTC <g4ftc@hotmail.com> wrote:
>
>> Hi Steve,
>>>
>>>
>>> I agree that any transformer can have a winding replaced, but would it be
>>> cost effective, particularly with a small transformer? It would probably
>>> be
>>> cheaper to buy a new unit.
>>>
>>
> Just have a go at it.
>
> S
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
------------------------------
Message: 4
Date: Fri, 30 Sep 2016 10:58:58 +1300
From: Steve Wright <stevewrightnz@gmail.com>
To: amps@contesting.com
Subject: Re: [Amps] Buzzing transformer
Message-ID: <50c3d0de-2d4b-809d-2b76-26ea7bc4ba1b@gmail.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
On 30/09/16 09:53, Jeff AC0C wrote:
> My PA76 buzzes a bit.? But I had another PA76 transformer from a guy
> who swapped it for a Dahl and that one sung like crazy.? Used it for a
> ton of key down power tests on an amp I was building and it never
> showed any other side effect than rattling.
Often it is about how the transformer is designed ;
A low flux density (more overall windings on the core) will give a quiet
transformer at idle with low standing loss, but worse regulation at full
load.
A high flux density (LESS overall windings on the core) will give a
humming transformer at idle with plenty of standing current flow, but
very good regulation at full load.
It's about what you need, or what you're prepared to tolerate.? This is
why power transformers on the side of the road hum loudly - they are
less concerned about idle current or a noisy transformer, than they are
about efficiency at full power.? Same principle applies in a HT PSU.? I
rewound the secondary only on a 2KVA (cont rating) isolating transformer
- and of course I ended up with a wicked boing on startup, a gnarly idle
hum, and a standby current of about an Amp hehe..? We did hook up the
rectifier incorrectly and destroyed a piece of 2.5mm copper wire that
someone thought was clever to put in the fuse holder.? Many thanks to
Manfred for the help on that particular adventure!
So if you want a balls-to-the-wall tube amp, the transformer is going to
hum somewhere...? ;)
Steve
------------------------------
Message: 5
Date: Thu, 29 Sep 2016 18:00:50 -0400
From: nemo zilch <nemozilch@gmail.com>
To: "amps@contesting.com" <amps@contesting.com>
Subject: [Amps] Ameritron/MFJ ROLLER INDUCTOR for GS35b amp
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Well, the replies are pretty close to 50/50 yea and nay.? I plan to build a
sort of breadboard of the basic amp to test cooling, rf choke, fil choke
and tank, etc.? So I think I'll chance it and invest in the roller inductor
and give it a try.? If anything weird happens, then I'll go to a switch and
tapped inductor.
As for roller inductors in general not shorting out the unused turns, that
is not necessarily the case.? I have a couple of large ones I bought at
Hamfests and both of them do short out the unused turns.? All that is
necessary is to connect the end of the shaft which the rolling contact
slides on to one end of the coil via a rotary contact.? Then connect
the the opposite end of the rotating coil via another rotary contact to the
plate circuit.? Use the end of the coil which connects to the rolling
contact shaft to connect to the loading capacitor side.? Pretty much
analogous to the tapped inductor/switch setup, perhaps more stray
inductance though.
My present HB amp uses a pair of 4-400's and I am using the roller
inductor/tuning capacitor from an old Johnson Thunderbolt amp and it works
fine all bands through 10M.
Thanks everyone for your replies, I value and appreciate them all.
Bob W4AOS
--
==========================================================
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Message: 6
Date: Thu, 29 Sep 2016 20:15:45 -0700
From: Tom Osborne <w7why@frontier.com>
To: amps@contesting.com
Subject: Re: [Amps] MFJ-(AMERITRON) ROLLER INDUCTOR?
Message-ID:
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I use an MFJ 989C tuner with a roller inductor and have never had a problem
with it.? I run about 6-700 watts with an 811H amp.
I have an 962C 'kw tuner' and have blown the bandswitch out twice.
For me the roller inductor is a better option ans lasts longer.? 73
Tom W7WHY
On Thu, Sep 29, 2016 at 7:42 AM, Catherine James <catherine.james@att.net>
wrote:
> I have been happy with the performance of the roller inductor in my
> ATR-30. While I can see that contacts may hold up better long-term in a
> switched inductor, the performance of the rollers seems to be quite
> acceptable.
>
> 73,
> Cathy
> N5WVR
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Message: 2
Date: Sat, 1 Oct 2016 18:19:37 +0000
From: Bill Turner <dezrat@outlook.com>
To: Amps group <amps@contesting.com>
Subject: Re: [Amps] Buzzing Transformer Follow-up Questions
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<CY1PR0301MB11961F7658F214F1058D232BC0C00@CY1PR0301MB1196.namprd03.prod.outlook.com>
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------------ ORIGINAL MESSAGE ------------(may be snipped)
On Fri, 30 Sep 2016 04:40:51 -0400, Roger wrote:
>If you want high vacuum there is little practical difference in pressure
>comparing atmospheric pressure to 10^-1 Torr, or 10^-5 Torr. It's close
>to 15 psi differential at either vacuum.
REPLY:
The more difficult issue might be obtaining a pressure vessel suitable
for transformers. Where I worked we had one custom made. Remember,
there is 15 PSI pressing in on hundreds of square inches. A disastrous
implosion is possible.
73, Bill W6WRT
------------------------------
Message: 3
Date: Sat, 1 Oct 2016 18:23:08 +0000
From: Bill Turner <dezrat@outlook.com>
To: Amps group <amps@contesting.com>
Subject: Re: [Amps] MFJ-(AMERITRON) ROLLER INDUCTOR?
Message-ID:
<CY1PR0301MB11965B1747C886FF04CA917DC0C00@CY1PR0301MB1196.namprd03.prod.outlook.com>
Content-Type: text/plain; charset="us-ascii"
------------ ORIGINAL MESSAGE ------------(may be snipped)
On Thu, 29 Sep 2016 20:15:45 -0700, Tom wrote:
>I use an MFJ 989C tuner with a roller inductor and have never had a problem
>with it. I run about 6-700 watts with an 811H amp.
>
>I have an 962C 'kw tuner' and have blown the bandswitch out twice.
REPLY:
Better yet, trim your antennas down to a 3:1 SWR or better and get an
amp such as an Alpha 9500 that can handle SWR up to 3:1. Nary a tuner
in sight at my shack. :-)
73, Bill W6WRT
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