Re: Amplifier Linearity
Does anyone besides me still use a 'scope in trapezoid pattern looking
at input vs. output linearity?
Seems like we're getting into "flat topping" tubes, etc just to get the max.
output level etc.
All the "it can't happen here" talk is really counter productive. If a guy
says
he can do it for heaven's sake let it go. Please don't try and prove how
clever you
are. It just doesn't impress me and wastes my time.
Thanks
73
ed K0KL
----- Original Message -----
From: <amps-request@contesting.com>
To: <amps@contesting.com>
Sent: Wednesday, September 26, 2007 9:56 AM
Subject: Amps Digest, Vol 57, Issue 52
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> Today's Topics:
>
> 1. Re: IMD (Chris Pedder)
> 2. Re: How much electrolitic for a HV supply ?
> (Peter Frenning [OZ1PIF])
> 3. Re: How much electrolitic for a HV supply ?
> (Hamilton Horta - PY2NI)
> 4. New SB-200 owner (r2robby)
> 5. Re: IMD (jeremy-ca)
> 6. Re: How much electrolitic for a HV supply ?
> (Peter Frenning [OZ1PIF])
> 7. Re: IMD (Steve Katz)
> 8. Re: IMD (Tom Rauch)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 26 Sep 2007 14:01:52 +0000
> From: Chris Pedder <chris@g3vbl.co.uk>
> Subject: Re: [Amps] IMD
> To: amps@contesting.com
> Message-ID: <20070926140305.97747319C5E@dayton.contesting.com>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> W1QJ wrote:
>
>
> >"AT highways speeds 55-70MPH you are probably using
> >less than a third of the total HP. I guess it is kinda the same thing
> >HUH?"
>
>
> Forgive me, but I don't understand where your figure of 'a third' comes
from.
>
> Is it something that "makes sense to you" and is this how you decided
> it was "right" for you?
>
> Chris
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 26 Sep 2007 15:35:34 +0200
> From: "Peter Frenning [OZ1PIF]" <peter@frenning.dk>
> Subject: Re: [Amps] How much electrolitic for a HV supply ?
> To: Hamilton Horta - PY2NI <py2ni@terra.com.br>
> Cc: amps@contesting.com
> Message-ID: <46FA6026.7090006@frenning.dk>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hamilton Horta - PY2NI skrev:
> > Hi everybody, is there any rule of thumb or whatever to determine
the
> > minimum
> > amount of electrolitic caps should one put in a HV power supply?
> > I am building a VHF PA with 1x GI-7B @ 2200V and another for a
friend of
> > mine with 2xGI-7B, I know that we are usually biased to use as much as
> > possible but I am really eager to know the minimum for these two amps
> > running 1xGI-7B and one with 2xGI-7B both operating at 2200V.
> >
> > Thanks a lot.
> >
> >
> Hi Horta,
> It's mostly a question of availability of suitable Caps. A well suited
> common type is 450V/220uF, you could get by with 6 in series, but that
> is cutting it very close, prudence would say use 8 in series giving a
> reasonable margin on V and some 27.5uF - that'll do at least up to 500mA
> and likely substantially more.
> I'm using this configuration in both a 2200V supply for a Gi7b (144MHz)
> and a 3000V supply for a QB-4/1100 (HF), both has given trouble-free
> operation for several years and good reports on audio quality.
>
> --
> Vy 73 de OZ1PIF/5Q2M, Peter
>
> ** CW: Who? Me? You must be joking!! **
> email: peter(no-spam-filler)@frenning.dk
> http://www.frenning.dk/oz1pif.htm
> Ph. +45 4619 3239
> Snailmail:
> Peter Frenning
> Ternevej 23
> DK-4130 Viby Sj.
> Denmark
> ***********************************
>
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 26 Sep 2007 11:12:28 -0300
> From: "Hamilton Horta - PY2NI" <py2ni@terra.com.br>
> Subject: Re: [Amps] How much electrolitic for a HV supply ?
> To: "Peter Frenning [OZ1PIF]" <peter@frenning.dk>
> Cc: amps@contesting.com
> Message-ID: <02ef01c80047$45af8d30$6501a8c0@NABLA>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Thanks a lot Peter, these figures are very close to what I thought,
> actually
> I was tempted to try (not in a definitive way but just run some tests)
with
> something around 6,7uF (7x 47uF in parallel) but only for the amp with
just
> one GI-7B. My feeling is that it?s going to prove me I am wrong :)
>
> 73
> Horta
> PY2NI
>
>
>
>
> ----- Original Message -----
> From: "Peter Frenning [OZ1PIF]" <peter@frenning.dk>
> To: "Hamilton Horta - PY2NI" <py2ni@terra.com.br>
> Cc: <amps@contesting.com>
> Sent: Wednesday, September 26, 2007 10:35 AM
> Subject: Re: [Amps] How much electrolitic for a HV supply ?
>
>
> > Hamilton Horta - PY2NI skrev:
> > > Hi everybody, is there any rule of thumb or whatever to determine
> the
> > > minimum
> > > amount of electrolitic caps should one put in a HV power supply?
> > > I am building a VHF PA with 1x GI-7B @ 2200V and another for a
> friend of
> > > mine with 2xGI-7B, I know that we are usually biased to use as much as
> > > possible but I am really eager to know the minimum for these two amps
> > > running 1xGI-7B and one with 2xGI-7B both operating at 2200V.
> > >
> > > Thanks a lot.
> > >
> > >
> > Hi Horta,
> > It's mostly a question of availability of suitable Caps. A well suited
> > common type is 450V/220uF, you could get by with 6 in series, but that
> > is cutting it very close, prudence would say use 8 in series giving a
> > reasonable margin on V and some 27.5uF - that'll do at least up to 500mA
> > and likely substantially more.
> > I'm using this configuration in both a 2200V supply for a Gi7b (144MHz)
> > and a 3000V supply for a QB-4/1100 (HF), both has given trouble-free
> > operation for several years and good reports on audio quality.
> >
> > --
> > Vy 73 de OZ1PIF/5Q2M, Peter
> >
> > ** CW: Who? Me? You must be joking!! **
> > email: peter(no-spam-filler)@frenning.dk
> > http://www.frenning.dk/oz1pif.htm
> > Ph. +45 4619 3239
> > Snailmail:
> > Peter Frenning
> > Ternevej 23
> > DK-4130 Viby Sj.
> > Denmark
> > ***********************************
> >
> >
> > Esta mensagem foi verificada pelo E-mail Protegido Terra.
> > Scan engine: McAfee VirusScan / Atualizado em 25/09/2007 / Vers?o:
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> > Proteja o seu e-mail Terra: http://mail.terra.com.br/
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> >
> >
> > --
> > No virus found in this incoming message.
> > Checked by AVG Free Edition.
> > Version: 7.5.488 / Virus Database: 269.13.30/1030 - Release Date:
> 25/9/2007 08:02
> >
> >
>
>
>
> ------------------------------
>
> Message: 4
> Date: Wed, 26 Sep 2007 11:21:43 -0300
> From: "r2robby" <robby@route2.pe.ca>
> Subject: [Amps] New SB-200 owner
> To: <amps@contesting.com>
> Message-ID: <002b01c80048$952f27c0$bf8d7740$@pe.ca>
> Content-Type: text/plain; charset="us-ascii"
>
> I am a new subscriber to this list and soon to be an ex-subscriber.
>
>
>
> I have recently bought a used SB-200 and plan on converting it to 6M
> monoband use. I do not plan to pay someone to do it even thought they
might
> do a better job.
>
>
>
> I thought I would get some useful information on this reflector. Not so
> far!
>
>
>
> When I signed up I was presented with the following information about the
> list:
>
>
>
> Welcome to the Amplifier mailing list! This list is intended for the
> exchange of information on HAM RADIO Amplifiers related topics ONLY. Our
> goal is to keep Amplifier information content high and noise low.
>
> DO NOT USE THIS REFLECTOR TO POST COMPLAINTS, PERSONAL CRITICISMS OR
> ATTACKS, AND DISCUSSIONS OF LIST OPERATION, ETC. VIOLATORS OF THIS POLICY
> WILL BE REMOVED IMMEDIATELY WITHOUT NOTICE.
>
> Be considerate of other subscribers who have bandwidth limitations and
edit
> posts for succinctness (include ONLY relevant excerpts of previous posts).
> NOTE: Top-posting complete previous messages are not allowed...please
either
> edit relevant parts of prior messages or delete them entirely. When
> responding to a specific individual, think carefully before copying to the
> other 1100 of us on the reflector.
>
> Minimize noise, minimize bandwidth, maximize Amplifier information, act
like
> gentlemen and enjoy!
>
>
>
> I thought it might be useful for some of you to read it again.
>
> If I am not able to get at any information that will benefit my project on
> this list, could someone kindly direct me to the correct one.
>
> Thanks in advance,
>
> 73,
>
> -Robby
> VY2SS
>
> Friendship is like peeing your pants,
> everyone can see it,
> but only you can feel the true warmth.
>
>
>
> ------------------------------
>
> Message: 5
> Date: Wed, 26 Sep 2007 10:29:33 -0400
> From: "jeremy-ca" <km1h@jeremy.mv.com>
> Subject: Re: [Amps] IMD
> To: "k7fm" <k7fm@teleport.com>, <Gudguyham@aol.com>
> Cc: amps@contesting.com
> Message-ID: <00b001c80049$ab1a0180$6500a8c0@KITTYMA123>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Thats a bunch of BS as usual from you.
>
> Any decent commercial amp will do more than its advertised at. Its called
> overhead and allows for tube aging. Using you distorted logic (pun
intended)
> an AL-1500 cant be run over 1500W otherwise you will have a poor signal.
>
> Since you appear to be an expert please explain how YOU would tune up a GG
> amp for best linearity.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "k7fm" <k7fm@teleport.com>
> To: <Gudguyham@aol.com>; <sm2ekm@telia.com>
> Cc: <amps@contesting.com>
> Sent: Wednesday, September 26, 2007 9:36 AM
> Subject: Re: [Amps] IMD
>
>
> > "AT highways speeds 55-70MPH you are probably using
> > less than a third of the total HP. I guess it is kinda the same thing
> > HUH?"
> >
> > I disagree. There is a local ham who, during calls to dx stations, runs
> > his
> > amp into a region above where he should. It is those peaks that cause
> > terrible buckshot. If the amplifier is tested at 600 watts, and the
> > distortion level is rated at that level, then that is all it should be
> > rated
> > at - period. Any power output above guaranteed linearity is
worthless.
> >
> > Colin K7FM
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
>
>
> ------------------------------
>
> Message: 6
> Date: Wed, 26 Sep 2007 16:37:01 +0200
> From: "Peter Frenning [OZ1PIF]" <peter@frenning.dk>
> Subject: Re: [Amps] How much electrolitic for a HV supply ?
> To: Hamilton Horta - PY2NI <py2ni@terra.com.br>
> Cc: amps@contesting.com
> Message-ID: <46FA6E8D.7090507@frenning.dk>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hamilton Horta - PY2NI skrev:
> > Thanks a lot Peter, these figures are very close to what I thought,
> > actually
> > I was tempted to try (not in a definitive way but just run some tests)
with
> > something around 6,7uF (7x 47uF in parallel) but only for the amp with
just
> > one GI-7B. My feeling is that it?s going to prove me I am wrong :)
> >
> > 73
> > Horta
> > PY2NI
> >
> >
> You can see how I,ve done it here:
> http://www.frenning.dk/OZ1PIF_HOMEPAGE/FL2000-QB.htm
>
> --
> Vy 73 de OZ1PIF/5Q2M, Peter
>
> ** CW: Who? Me? You must be joking!! **
> email: peter(no-spam-filler)@frenning.dk
> http://www.frenning.dk/oz1pif.htm
> Ph. +45 4619 3239
> Snailmail:
> Peter Frenning
> Ternevej 23
> DK-4130 Viby Sj.
> Denmark
> ***********************************
>
>
>
> ------------------------------
>
> Message: 7
> Date: Wed, 26 Sep 2007 07:53:22 -0700
> From: Steve Katz <stevek@jmr.com>
> Subject: Re: [Amps] IMD
> To: jeremy-ca <km1h@jeremy.mv.com>, amps@contesting.com
> Message-ID:
> <C770317F90C7CE45B0C92E844FB89BD2CBBE60@mail05.corp.jmr.com>
> Content-Type: text/plain
>
> Carl,
>
>
>
> The AL-572 uses four 572Bs, not three, and is rated 1300W PEP; however
> that's not its key-down CW rating. At 325W rated PEP output per tube,
it's
> rated exactly at the Cetron spec limit.
>
>
>
> 73
>
>
>
> Steve WB2WIK/6
>
>
>
> _____
>
> From: jeremy-ca [mailto:km1h@jeremy.mv.com]
> Sent: Tuesday, September 25, 2007 5:06 PM
> To: Steve Katz; amps@contesting.com
> Subject: Re: IMD
>
>
>
> >If you look at the AL-1200 specs they claim 1200W with 3 tubes so no
> matter how anyone wants to spin it Im not doing anything different at 750W
> with two.<
>
>
>
> ::The AL-1200 uses a single 3CX1200A7 and runs 1500W output using a tube
> having 1200W anode dissipation. You must have a very different AL-1200.
>
>
>
> 73, Steve WB2WIK/6
>
>
>
> Sorry, I meant the AL-572 which you could just as easily have found by
going
> a bit further on their web site.
>
>
>
> Carl
>
>
>
>
>
>
>
>
>
>
>
> ----- Original Message -----
>
> From: Steve Katz <mailto:stevek@jmr.com>
>
> To: Gudguyham@aol.com <mailto:Gudguyham@aol.com> ; la7sl@online.no
> <mailto:la7sl@online.no> ; amps@contesting.com
<mailto:amps@contesting.com>
> ; km1h@jeremy.mv.com <mailto:km1h@jeremy.mv.com>
>
> Sent: Tuesday, September 25, 2007 4:37 PM
>
> Subject: RE: [Amps] 6 mtrs:
>
>
>
> Yep, things do change.
>
>
>
> I want to see the spectral analysis of the SB-200 (monoband or otherwise)
> operating at 750W PEP output on SSB, closing in on IM3-5-7 especially.
>
>
>
> When I've used this tube, it's provided only about 8 dB power gain. With
> 100W drive that's <750W output, at any frequency. The Cetron "ratings"
per
> the old data sheet I have is 30 MHz max for full ratings; 7.5 dB gain;
2.4kV
> max and 250mA max per tube, yielding 300W output per tube (the data
> obviously assumes 50% efficiency). At even 65% efficiency to achieve 750W
> out would be 1153W in, and 403W dissipation from a pair of tubes rated for
> 320W max dissipation at 30 MHz.
>
>
>
> I fully agree anything's possible.
>
>
>
> WB2WIK/6
>
>
>
>
>
>
> _____
>
>
> From: Gudguyham@aol.com [mailto:Gudguyham@aol.com]
> Sent: Tuesday, September 25, 2007 1:28 PM
> To: stevek@jmr.com; la7sl@online.no; amps@contesting.com;
km1h@jeremy.mv.com
> Subject: Re: [Amps] 6 mtrs:
>
>
>
> In a message dated 9/25/2007 12:36:55 P.M. Eastern Daylight Time,
> stevek@jmr.com writes:
>
> But driving a pair of 572B's to 750W output looks to a retired E
> professional
> like pushing an old VW beetle to 100MPH would look to an auto engineer:
> Risky,- at best :-)
> May be I am too conservative ??? ...
>
> Hi Steve, the Sb-200 operators manual says that 100 watts is permissible,
> Just because you are used to an SB-200 on HF or similar amplifier that
with
> 100 watts makes only about 650 watts out, then why is the same 100 watts
of
> drive any different on 6 meters? To me, 100 watts drive is 100 watts
drive
> either on 80 meters or 6 meters. I think some of you guys have to think
> "outside the box". When one fine tunes a design and makes it specific for
a
> specific frequency we are talking a horse of a different color than an all
> band amplifier. Things change.
>
>
>
>
> _____
>
>
> See what's new at AOL.com <http://www.aol.com?NCID=AOLCMP00300000001170>
> and Make AOL Your
> <http://www.aol.com/mksplash.adp?NCID=AOLCMP00300000001169> Homepage.
>
>
>
> ------------------------------
>
> Message: 8
> Date: Wed, 26 Sep 2007 10:57:57 -0400
> From: "Tom Rauch" <w8ji@contesting.com>
> Subject: Re: [Amps] IMD
> To: <amps@contesting.com>
> Message-ID: <007c01c8004d$a4bf9580$640fa8c0@radioroom>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> >> I disagree. There is a local ham who, during calls to dx
> >> stations, runs
> >> his
> >> amp into a region above where he should. It is those
> >> peaks that cause
> >> terrible buckshot. If the amplifier is tested at 600
> >> watts, and the
> >> distortion level is rated at that level, then that is all
> >> it should be
> >> rated
> >> at - period. Any power output above guaranteed
> >> linearity is worthless.
> >> Colin K7FM
>
>
> > Thats a bunch of BS as usual from you.
>
> Why is that line necessary in a technical exchange? IMO he
> was making a valid point.
>
>
> > Any decent commercial amp will do more than its advertised
> > at. Its called
> > overhead and allows for tube aging. Using you distorted
> > logic (pun intended)
> > an AL-1500 cant be run over 1500W otherwise you will have
> > a poor signal.
>
>
> Please check this link:
>
> http://www.ameritron.com/man/pdf/AL-1500.pdf
>
>
> If we actually read the specs, it was tested in excess of
> 2500W PEP in a two tone test. The IM3 at that level was
> better than -34dB from one tone of the two. That's -40dB PEP
> (crummy ARRL method).
>
> It is a little cleaner at 1500W, but not much.
>
> By the way the tested IM3 was worse case drive level using
> two isolated exciters through a combiner rather than a sweet
> spot caused by using a typical radio nto the amp. It is
> possible if you raise and lower power (especially using a
> regular radio as a test generator) to find "sweet spots"
> where certain IM products are better over a narrow range.
> Many systems don't follow a classic 3:1 IM vs. carrier level
> change. In other words if you increase carrier power by 1 dB
> IM should increase 3dB, but that doesn't often work in real
> systems.
>
> If someone is measuring IM using a radio that has IM
> anywhere remotely close to the PA IM levels, then they are
> fooling themselves. They aren't measuring anything. It takes
> an exceptionally clean source to obtain accurate data, and
> you won't find that in a modern radio (although a class A
> FT1000MP MKV kept well out of ALC gets close).
>
> I also have the opinion that IM should be determined at the
> maximum specified or expected power, not some lower number.
>
> 73 Tom
>
>
>
>
> ------------------------------
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
> End of Amps Digest, Vol 57, Issue 52
> ************************************
>
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