Good Day Gentlemen. I have been reading the mail for quite a while. I will
admit I know nothing. I am putting a tube in a box , I have a tank circuit
and power supply. My first question is on the input circuit.
How do you set it, SWR meter between radio and amp under low power? Antenna
analyzer with no power to amp ? Do you need a meter on the grid? If you have
time I would appreciate and words of wisdom. The schematic I am using for
the tube is the Zl1axb 600w amp.
http://www.raibeam.com/zl1axb/813_amp.html
It will be used on 20/17/15m at first. I will consider it a 20m mono band
until I get the bugs worked out
The box was given to me with a bad tube for work done, a SB-230. I have the
813 and spare and a new filament transformer. I have moved the tank circuit
forward 2.5" and have plenty of room for the 813. Parts are no problem but
is there some where I can read the basic steps. I am now replacing the basic
P/S diodes and relays from the 30 year old amp.
Rich, Kd0zz
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of amps-request@contesting.com
Sent: Wednesday, March 17, 2010 10:36 PM
To: amps@contesting.com
Subject: Amps Digest, Vol 87, Issue 46
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When replying, please edit your Subject line so it is more specific
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Today's Topics:
1. Re: Teflon Caps (Carl)
2. Re: placement of RF choke bypass cap. (Bill, W6WRT)
3. Re: placement of RF choke bypass cap. (Gary Schafer)
4. Re: placement of RF choke bypass cap. (Carl)
5. Re: Teflon Caps (Bill Fuqua)
6. Re: Teflon Caps (Ron Youvan)
7. Re: Teflon Caps (donroden@hiwaay.net)
8. Re: Teflon Caps (Bill, W6WRT)
9. Re: placement of RF choke bypass cap. (Bill, W6WRT)
10. Re: placement of RF choke bypass cap. (Bill, W6WRT)
11. Are exciter RF delays to prevent hot keying cataloged
anywhere? (Rob Stampfli)
----------------------------------------------------------------------
Message: 1
Date: Wed, 17 Mar 2010 15:22:49 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] Teflon Caps
To: <ToddRoberts2001@aol.com>, <amps@contesting.com>
Message-ID: <016b01cac607$3db1e5a0$6501a8c0@DAVES>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Tesla generators run at microscopic current levels. Its the RF current that
often destroy caps in amps.
Carl
KM1H
----- Original Message -----
From: <ToddRoberts2001@aol.com>
To: <amps@contesting.com>
Sent: Wednesday, March 17, 2010 1:28 PM
Subject: Re: [Amps] Teflon Caps
> Tesla Coil builder sites are good places to read about different
> builder's experiences with high voltage caps.
>
> Their advice is to limit the voltage across each capacitor to no
> more than 5KV. Many of them are using Polyethylene sheet as
> insulation for their high voltage caps and they recommend
> immersing them in oil. They subject their capacitors to tremendous
> peak voltages and currents as most Tesla coils are based on spark-gap
> generators of RF. Their capacitors are all fixed ones though, not
> variable.
>
> Nowadays many Tesla Coil builders have switched to Multi-Mini-Capacitors
> or MMCs. These are strings of 1500 - 2000 volt DC rated polypropylene
> caps wired in series-parallel. They said it is best to use the metal
> foil/film types
> and not metallized/film types.
>
> They say that if the voltage is 5KV or less Corona is usually not a
> problem.
> Also some companies do make grades of Teflon that are highly Corona
> resistant so a lot
> depends on the grade of Teflon used for a high voltage capacitor.
>
> So far I have had good luck building trombone-style high voltage variable
> capacitors for a transmitting loop antenna using a thin sheet of Standard
> Teflon
> wrapped tightly over copper pipes that slide inside slightly larger copper
> pipes
> for the loop tuning variable capacitor. This would probably work even
> better with
> modified-grade Teflon but don't know how expensive that stuff might be.
>
> So far no flashovers or any problems with heating at a calculated nearly 4
> KV RF
> in the loop and 8 amperes of RF current using standard Teflon sheet. Very
> inexpensive to build. Teflon makes very high Q low-loss capacitors needed
> for a
> transmitting loop.
>
> 73 Todd WD4NGG
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
------------------------------
Message: 2
Date: Wed, 17 Mar 2010 12:53:28 -0700
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
Subject: Re: [Amps] placement of RF choke bypass cap.
To: <amps@contesting.com>
Message-ID: <9rb2q59j7vb3gp1e9lknj087o1hqrivr5u@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE:
On Wed, 17 Mar 2010 07:24:00 -0700, "Jim Thomson" <Jim.thom@telus.net>
wrote:
>## How do u know there will be RF flowing on the underside
>of the chassis ?? ... asuming it has a ..'normal' chassis .
>If the grid trip is below the chassis, and also uses rf bypass caps,
>it should not be a problem. ... at least on paper.
REPLY:
The RF will be flowing through the thickness of the chassis, both
sides. This is not a transmission line or piece of coax.
And the problem with the grid trip or other circuit is not easily
cured with bypass caps used in the ordinary way. The problem there is
a ground loop condition, which acts like a little "RF generator",
injecting RF into anything connected across part of the loop or from a
point on the loop to a different ground. . It's best to just stay away
from the loop entirely. And better yet to not create one that long in
the first place.
A certain amount of ground loop in the tank circuit is unavoidable if
the tune and load caps are mounted to the chassis, but to create a
second one 11 inches long is ridiculous.
73, Bill W6WRT
------------------------------
Message: 3
Date: Wed, 17 Mar 2010 16:01:25 -0400
From: "Gary Schafer" <garyschafer@comcast.net>
Subject: Re: [Amps] placement of RF choke bypass cap.
To: <dezrat1242@yahoo.com>, <amps@contesting.com>
Message-ID: <20100317200126.C23B81B606DE@dayton.contesting.com>
Content-Type: text/plain; charset="us-ascii"
RF will not flow thru the chassis from one side to the other.
Remember "skin effect"?
73
Gary K4FMX
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Bill, W6WRT
> Sent: Wednesday, March 17, 2010 3:53 PM
> To: amps@contesting.com
> Subject: Re: [Amps] placement of RF choke bypass cap.
>
> ORIGINAL MESSAGE:
>
> On Wed, 17 Mar 2010 07:24:00 -0700, "Jim Thomson" <Jim.thom@telus.net>
> wrote:
>
> >## How do u know there will be RF flowing on the underside
> >of the chassis ?? ... asuming it has a ..'normal' chassis .
> >If the grid trip is below the chassis, and also uses rf bypass caps,
> >it should not be a problem. ... at least on paper.
>
> REPLY:
>
> The RF will be flowing through the thickness of the chassis, both
> sides. This is not a transmission line or piece of coax.
>
> And the problem with the grid trip or other circuit is not easily
> cured with bypass caps used in the ordinary way. The problem there is
> a ground loop condition, which acts like a little "RF generator",
> injecting RF into anything connected across part of the loop or from a
> point on the loop to a different ground. . It's best to just stay away
> from the loop entirely. And better yet to not create one that long in
> the first place.
>
> A certain amount of ground loop in the tank circuit is unavoidable if
> the tune and load caps are mounted to the chassis, but to create a
> second one 11 inches long is ridiculous.
>
> 73, Bill W6WRT
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
------------------------------
Message: 4
Date: Wed, 17 Mar 2010 16:07:32 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] placement of RF choke bypass cap.
To: <dezrat1242@yahoo.com>, <amps@contesting.com>
Message-ID: <01ac01cac60d$7c5b4070$6501a8c0@DAVES>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
----- Original Message -----
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
To: <amps@contesting.com>
Sent: Wednesday, March 17, 2010 3:53 PM
Subject: Re: [Amps] placement of RF choke bypass cap.
> ORIGINAL MESSAGE:
>
> On Wed, 17 Mar 2010 07:24:00 -0700, "Jim Thomson" <Jim.thom@telus.net>
> wrote:
>
>>## How do u know there will be RF flowing on the underside
>>of the chassis ?? ... asuming it has a ..'normal' chassis .
>>If the grid trip is below the chassis, and also uses rf bypass caps,
>>it should not be a problem. ... at least on paper.
>
> REPLY:
>
> The RF will be flowing through the thickness of the chassis, both
> sides. This is not a transmission line or piece of coax.
** Say what????
Carl
>
> And the problem with the grid trip or other circuit is not easily
> cured with bypass caps used in the ordinary way. The problem there is
> a ground loop condition, which acts like a little "RF generator",
> injecting RF into anything connected across part of the loop or from a
> point on the loop to a different ground. . It's best to just stay away
> from the loop entirely. And better yet to not create one that long in
> the first place.
>
> A certain amount of ground loop in the tank circuit is unavoidable if
> the tune and load caps are mounted to the chassis, but to create a
> second one 11 inches long is ridiculous.
>
> 73, Bill W6WRT
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
------------------------------
Message: 5
Date: Wed, 17 Mar 2010 16:08:06 -0400
From: Bill Fuqua <wlfuqu00@uky.edu>
Subject: Re: [Amps] Teflon Caps
To: "amps@contesting.com" <amps@contesting.com>
Message-ID: <5.1.1.5.2.20100317160350.02c22bd0@exchange.uky.edu>
Content-Type: text/plain; charset="us-ascii"; format=flowed
This reminds me that some where I have a very strange variable capacitor
that is oil filled and has a bellows to allow operation at high altitudes.
It is obviously an RF variable, perhaps a pre-vacuum capacitor type for
high altitudes and voltages.
It is neat because it is enclosed in a glass envelope and you can see all
the insides. It is constructed as a usual capacitor with rotor and stator
plates. Not like the coaxial ones as in vacuum capacitors.
Needless to say a rotary shaft vacuum connection would be difficult
but not impossible.
73
Bill wa4lav
------------------------------
Message: 6
Date: Wed, 17 Mar 2010 16:49:35 -0400
From: Ron Youvan <ka4inm@tampabay.rr.com>
Subject: Re: [Amps] Teflon Caps
To: amps <amps@contesting.com>
Message-ID: <4BA1405F.8040201@tampabay.rr.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> This reminds me that some where I have a very strange variable capacitor
> that is oil filled and has a bellows to allow operation at high altitudes.
> It is obviously an RF variable, perhaps a pre-vacuum capacitor type for
> high altitudes and voltages.
> It is neat because it is enclosed in a glass envelope and you can see all
> the insides. It is constructed as a usual capacitor with rotor and stator
> plates. Not like the coaxial ones as in vacuum capacitors.
I have one of these also, the chap that gave it to me told me it came out
of a army
transmitter using one or two 813 pentodes. (possibly an ART-13)
The problem with it is the shaft is about 3/8" long with half of a flexible
coupling
welded or pressed on to the shaft. Because of this thread I have been
thinking about it.
--
Ron KA4INM - I'm proud to be Chuck's pop!
------------------------------
Message: 7
Date: Wed, 17 Mar 2010 15:50:03 -0500
From: donroden@hiwaay.net
Subject: Re: [Amps] Teflon Caps
Cc: Amps@contesting.com
Message-ID: <20100317155003.196343f1695olg1n@webmail.hiwaay.net>
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"
I had ( have ? ) one of those babies somewhere. Light yellow oil.
Rummaging through the ham shack.
Don WA4NPL
Quoting "Bill Fuqua" <wlfuqu00@uky.edu>:
>
> This reminds me that some where I have a very strange variable capacitor
> that is oil filled and has a bellows to allow operation at high altitudes.
> It is obviously an RF variable, perhaps a pre-vacuum capacitor type for
> high altitudes and voltages.
> It is neat because it is enclosed in a glass envelope and you can see all
> the insides. It is constructed as a usual capacitor with rotor and stator
> plates. Not like the coaxial ones as in vacuum capacitors.
> Needless to say a rotary shaft vacuum connection would be difficult
> but not impossible.
> 73
> Bill wa4lav
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
------------------------------
Message: 8
Date: Wed, 17 Mar 2010 19:39:35 -0700
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
Subject: Re: [Amps] Teflon Caps
To: <amps@contesting.com>
Message-ID: <4e43q5pus2j75kap65g55652tvqiscs6n4@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE:
On Wed, 17 Mar 2010 15:22:49 -0400, "Carl" <km1h@jeremy.mv.com> wrote:
>Tesla generators run at microscopic current levels. Its the RF current that
>often destroy caps in amps.
REPLY:
The output of a Tesla generator is usually "microscopic", but remember
there is a resonant tank circuit in there too, and we all know about
those. :-)
73, Bill W6WRT
------------------------------
Message: 9
Date: Wed, 17 Mar 2010 19:43:33 -0700
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
Subject: Re: [Amps] placement of RF choke bypass cap.
To: <amps@contesting.com>
Message-ID: <2n43q5d4vhi5usmg28jasn3mun58hq8hb5@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE:
On Wed, 17 Mar 2010 16:01:25 -0400, "Gary Schafer"
<garyschafer@comcast.net> wrote:
>RF will not flow thru the chassis from one side to the other.
>Remember "skin effect"?
REPLY:
II guess my padding caps, which are on one side of the chassis are not
really connected to the load cap, which is on the other.
Right?
73, Bill W6WRT
------------------------------
Message: 10
Date: Wed, 17 Mar 2010 19:52:22 -0700
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
Subject: Re: [Amps] placement of RF choke bypass cap.
To: <amps@contesting.com>
Message-ID: <7953q51f5b0nu89fu035n6uto3gctr0mqp@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE:
On Wed, 17 Mar 2010 16:07:32 -0400, "Carl" <km1h@jeremy.mv.com> wrote:
>** Say what????
REPLY:
Ummmmm..... perhaps you could be a wee bit more specific with your
question?
73, Bill W6WRT
------------------------------
Message: 11
Date: Wed, 17 Mar 2010 23:36:04 -0400
From: Rob Stampfli <rob@cboh.org>
Subject: [Amps] Are exciter RF delays to prevent hot keying cataloged
anywhere?
To: amps@contesting.com
Message-ID: <20100318033604.GA8911@keevey>
Content-Type: text/plain; charset=us-ascii
I know most rigs employ a delay of some milliseconds between the time
when their amp relay closes and RF transmission begins in order to prevent
hot keying problems. On some, this is even an adjustable parameter, but
on most it is fixed.
Has anyone compiled a list of delay values for the various commercial
transceivers that have been sold over the years? It would seem that
such a list would be quite useful to hams trying to retrofit a new amp
into their shack. In addition to the delay figure, one could also add
the voltage/amperage limits of the keying circuit, too.
Inquiring minds...
Rob / KD8WK
------------------------------
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