ALC is old and slow. I would not recommend relying on ALC to preserve a
tube or even to keep an ssb signal free of splatter. Proper drive level and
tuning the amp at FULL output is a safe and secure way. If your PS cannot
handle it use dits at 55-60 wpm with about a 40% duty cycle. Dummy load
please. It should never take more than about 3-4 seconds to tune an amp
anyway.
I can tell that my Orion has a leading spike on cw. I can easily see it on
the overdrive led of the titan 425. From the operation of the led I assume
the spike is only a few watts higher than the pwr setting. For instance it
takes 40 watts of drive to run the 425 to 1500 watts on 80, but I get the
led flickering on the first few code elements. If I back the pwr setting on
the Orion down to about 35 I do not see the flicker in the first few
elements. I do not see this when using a TS850 for whatever that is worth.
To me the difference between 1200 and 1500 watts out is inconsequential so I
never drive my amps full tilt and avoid the problem. If I had a scope it
would be fun to determine just how big that spike is. If it were even twice
the indicated pwr out the 3cx800's would be toast quick. Not sure I really
want to know....73 bob de w9ge
----- Original Message -----
From: <tentec-request@contesting.com>
To: <tentec@contesting.com>
Sent: Wednesday, August 18, 2004 7:22 PM
Subject: TenTec Digest, Vol 20, Issue 77
> Send TenTec mailing list submissions to
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>
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> or, via email, send a message with subject or body 'help' to
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> than "Re: Contents of TenTec digest..."
>
>
> Today's Topics:
>
> 1. Re: TT [TenTec] Spare Tubes (Tommy)
> 2. Ten Tec amps and ALC (Rob Atkinson, K5UJ)
> 3. Re: Ten Tec amps and ALC (Jim Brown)
> 4. re Ten Tec amps and ALC (Rob Atkinson, K5UJ)
> 5. Re: Ten Tec amps and ALC (Ken Brown)
> 6. Re: re Ten Tec amps and ALC (Ken Brown)
> 7. FOR SALE: OMNI-V , 705 Mic, 218 narrow SSB filter
> (Michael, Dana A)
> 8. Re: Ten Tec amps and ALC (Jim Brown)
> 9. Re: Ten Tec amps and ALC (Stuart Rohre)
> 10. Re: The QSK of QSK (DennisKT5D@aol.com)
> 11. High performance radios (DennisKT5D@aol.com)
> 12. Re: TT Re: [TenTec] Ten Tec amps and ALC (Tommy)
> 13. RE: TT Re: [TenTec] Ten Tec amps and ALC (al_lorona@agilent.com)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 18 Aug 2004 15:50:13 -0400
> From: "Tommy" <aldermant@alltel.net>
> Subject: Re: TT [TenTec] Spare Tubes
> To: "Jim Brown" <jim@audiosystemsgroup.com>, <tentec@contesting.com>
> Message-ID: <002901c4855c$946c56b0$5dda27a2@w4bqf2>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Ken is correct. However, the 3CX has an Eimac suggested replacement, which
> is 3CXP800A7. These aparently are more rugged than the originals and are
> what is presently being used in most medical equipment. I have the 3CXP's
> in my 425 and they work just fine and run about $250-$275 each (unless you
> have a good friend who repairs medical gear!!).
>
> Tom - W4BQF
>
> ----- Original Message -----
> From: "Jim Brown" <jim@audiosystemsgroup.com>
> To: "Ten Tec List" <tentec@contesting.com>
> Sent: Wednesday, August 18, 2004 2:37 PM
> Subject: TT [TenTec] Spare Tubes
>
>
> > If I wanted to buy spare tubes for my Titan 425 (3CX800A7), where would
I
> > buy them and what's the "right" price?
> >
> > Jim K9YC
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 18 Aug 2004 21:22:07 +0000
> From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
> Subject: [TenTec] Ten Tec amps and ALC
> To: tentec@contesting.com
> Message-ID: <BAY12-F6VJWrGW6Ex3A000b401f@hotmail.com>
> Content-Type: text/plain; format=flowed
>
> This recent review of the IC7800 in eHam:
>
> <<<Hi, my name is Marty, W3QK, and I just sent back my Orion, as when near
> to a strong R.F. source, it locked up. I changed coax jumpers, VSWR (
which
> was just fine ), and would have run an ALC line, but the Orion has no
> external ALC. I am heading into purchasing an Icom 7800 and heard
something
> about the Front End having problems, but I think that the source didn't
even
> own one. I am visually impaired and run almost all my Icoms with computer
> control. If there is anything that you dislike about it, please tell me.
My
> email is martyjp@comcast.net Otherwise, it will only be about 2 weeks till
I
> get mine. 73 and g.b. all of you. >>>
>
> raises an interesting question (interesting to me at least).
>
> Why do Ten Tec rigs lack an ALC jack and why do Ten Tec amps lack an ALC
> input?
> It has occurred to me when I have been driving my Centurion with nonTen
Tec
> exciters.
> No problems as far as I can tell, however, it seems to be something Ten
Tec
> would want to
> include in their amps if they were interested in selling them to hams
> running other than Ten Tec
> exciters.
>
> Rob/K5UJ
>
> _________________________________________________________________
> Express yourself instantly with MSN Messenger! Download today - it's FREE!
> http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/
>
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 18 Aug 2004 16:27:02 -0500
> From: "Jim Brown" <jim@audiosystemsgroup.com>
> Subject: Re: [TenTec] Ten Tec amps and ALC
> To: "tentec@contesting.com" <tentec@contesting.com>
> Message-ID: <20040818212736.21EE57D42@gw1.nlenet.net>
> Content-Type: text/plain; charset="us-ascii"
>
> On Wed, 18 Aug 2004 21:22:07 +0000, Rob Atkinson, K5UJ wrote:
>
> >Why do Ten Tec rigs lack an ALC jack and why do Ten Tec amps lack an ALC
> >input?
>
> Modern rigs and amps don't generally require ALC, and, in fact, ALC is
generally not
> recommended for many amps and rigs. As I understand it, ALC is mainly a
leftover
> from the "old days." My Hercules 444 and Titan 425, both introduced in
the early 80's,
> DO have an ALC output.
>
> Jim Brown K9YC
>
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Wed, 18 Aug 2004 22:04:53 +0000
> From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
> Subject: [TenTec] re Ten Tec amps and ALC
> To: tentec@contesting.com
> Message-ID: <BAY12-F42Vh4isXUMAy000b448b@hotmail.com>
> Content-Type: text/plain; format=flowed
>
> <<<Modern rigs and amps don't generally require ALC, and, in fact, ALC is
> generally not
> recommended for many amps and rigs. As I understand it, ALC is mainly a
> leftover
> from the "old days." My Hercules 444 and Titan 425, both introduced in
the
> early 80's,
> DO have an ALC output.>>>
>
> As far as I know, every recently designed rig and amp out there other than
> Ten Tec has
> ALC jacks so, I presume, the amp can tell the exciter "I'm being
overdriven!
> Curb your enthusiasm!"
> And this seems to me, to be a sensible thing to have, especially with amps
> that don't need much drive and have expensive tubes such as the 3cx800
amps.
> The idea that the exciter has internal ALC controlling it so it won't
go
> over 100 w. won't save you in this case. Owners of grid driven amps using
> 3-500s didn't have to sweat it very much but now, there are more 200 watt
> rigs appearing so even the Centurion/L4/2K/HF-2000/AL82/SB220 guys are
> vulnerable (did I leave anyone out? :). Perhaps I'm missing the point
of
> the amp to rig ALC link. If everyone could just back off on the PA
> collector current to prevent overdrive I guess there would be no need for
> external ALC control but then I don't think I'd see rear panel ALC jacks
on
> new rigs if that were true.
>
> Rob/K5UJ
>
> _________________________________________________________________
> Is your PC infected? Get a FREE online computer virus scan from McAfee®
> Security. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
>
>
>
> ------------------------------
>
> Message: 5
> Date: Wed, 18 Aug 2004 12:06:58 -1000
> From: Ken Brown <ken.d.brown@verizon.net>
> Subject: Re: [TenTec] Ten Tec amps and ALC
> To: tentec@contesting.com
> Message-ID: <4123D302.2050509@verizon.net>
> Content-Type: text/plain; charset=us-ascii; format=flowed
>
>
> >
> > Why do Ten Tec rigs lack an ALC jack and why do Ten Tec amps lack an
> > ALC input?
>
> I thought the the ALC connection on an amplifier was an OUTPUT. When the
> drive level to the amplifier approached an amount that would drive the
> amplifier into non-linearity, the signal from the amplifier ALC output
> was supposed to act as a sort of negative feedback, reducing the drive
> from the exciter.
>
> With so many exciters that put out 100 watts and more, and so many grid
> driven PAs that need only about 60 watts drive, it would seem like ALC
> would still be a good thing to have. I don't know whether there was ever
> any standard established as far as ALC volltage level (or even polarity)
> to produce a specific exciter gain reduction. With no standard
> established, it may be better not to have ALC at all, when mixing brands
> of exciters and PAs.
>
> My Titan 425 has an OVERDRIVE indicator. If I ever operated SSB, AM,
> PSK31 or other modes where multiple tones are used and amplitude
> linearity is important, I would adjust my exciter power level to make
> sure that the OVERDRIVE indicator on the Titan never comes on. In fact,
> operating CW, I do that anyway. Just not for all the same reasons.
>
> DE N6KB
>
>
>
>
>
> ------------------------------
>
> Message: 6
> Date: Wed, 18 Aug 2004 12:13:08 -1000
> From: Ken Brown <ken.d.brown@verizon.net>
> Subject: Re: [TenTec] re Ten Tec amps and ALC
> To: tentec@contesting.com
> Message-ID: <4123D474.3050108@verizon.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
> > Centurion/L4/2K/HF-2000/AL82/SB220 guys are vulnerable (did I leave
> > anyone out? :).
>
> Drake L7 also uses a pair of 3-500Z cathode driven. Since you included
> the L4, I guess you get partial credit.
>
> DE N6KB
>
>
>
>
> ------------------------------
>
> Message: 7
> Date: Tue, 17 Aug 2004 08:35:29 -0400
> From: "Michael, Dana A" <dana.michael@tycoelectronics.com>
> Subject: [TenTec] FOR SALE: OMNI-V , 705 Mic, 218 narrow SSB filter
> To: "'tentec@contesting.com'" <tentec@contesting.com>
> Message-ID:
> <98435D0AC03ED711972A00508BF9F6720F382374@ammex008.amp.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> For Sale:
>
> Ten-Tec OMNI-V and 705 desk Mic and manual. $775
>
> In good condition with a few scratches on the sides of the case.
>
> Ten-Tec #218 1.8 khz at 9 mhz narrow SSB filter $75
>
> TNX es 73,
> D.A. "Mike" Michael W3TS
> 129 Church Lane
> Halifax, Pa. 17032-8372
>
> Work phone 1-717-810-2860 from 7am to 3pm EST
> Home phone 1-717-896-3973 from 4pm to 10pm EST
>
>
>
>
> ------------------------------
>
> Message: 8
> Date: Wed, 18 Aug 2004 17:32:29 -0500
> From: "Jim Brown" <jim@audiosystemsgroup.com>
> Subject: Re: [TenTec] Ten Tec amps and ALC
> To: "tentec@contesting.com" <tentec@contesting.com>
> Message-ID: <20040818223303.59C427D42@gw1.nlenet.net>
> Content-Type: text/plain; charset="us-ascii"
>
> On Wed, 18 Aug 2004 12:06:58 -1000, Ken Brown wrote:
>
> >y Titan 425 has an OVERDRIVE indicator. If I ever operated SSB, AM,
> >PSK31 or other modes where multiple tones are used and amplitude
> >linearity is important, I would adjust my exciter power level to make
> >sure that the OVERDRIVE indicator on the Titan never comes on.
>
> The overdrive indicator is important for something even more important
> than linearity -- the life of the output tubes!
>
> 3CX800A7's do not like to be overdriven, and the manual has a bold
> print warning that 120 mA of grid current should NEVER be exceeded.
> This element of the tube's rating is, apparently, even more critical than
> plate current or dissipation.
>
> I have learned that Eimac has a newer version of this tube designed for
> pulse operation and with an internal structure higher voltage rating
> (3500V). It is directly interchangeable with the 3CX800A7. As near as I
> can tell, there are no changes in the grid current rating.
>
> A power amp using the 3CPX800A7 at a higher plate voltage could be
> driven far more easily than one using the 3CX800A7, making it far less
> likely that it would be overdriven.
>
> Here are some interesting links on the topic.
>
> http://www.hamradiomarket.com/articles/Titan%20P%20Hybrid.htm
>
> http://www.cpii.com/eimac/ab25.htm
>
> Jim Brown K9YC
>
>
>
>
> ------------------------------
>
> Message: 9
> Date: Wed, 18 Aug 2004 17:37:15 -0500
> From: "Stuart Rohre" <rohre@arlut.utexas.edu>
> Subject: Re: [TenTec] Ten Tec amps and ALC
> To: <tentec@contesting.com>
> Message-ID: <005e01c48573$e949aef0$4e100a0a@rohredt2000>
>
> An overdrive indicator on an amplifier seems an excellent feature, to
avoid
> the possible non-compatibility of ALC circuits in light of no universal
ALC
> standard.
> -Stuart
> K5KVH
>
>
>
>
> ------------------------------
>
> Message: 10
> Date: Wed, 18 Aug 2004 18:45:25 EDT
> From: DennisKT5D@aol.com
> Subject: Re: [TenTec] The QSK of QSK
> To: tentec@contesting.com
> Message-ID: <b8.6016eb13.2e553605@aol.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> Had my 425 to Ten Tec last week. LED failed (go figure how often that
> happens), everything else checked out fine. I asked the service manager
about
> replacing the vacuum relay or at least buying a back up. Not necessary was
the
> official reply. The older, original units had problems but the newer
KiloVac units
> solved it. Okay, QSK away and enjoy. Besides, it'll probably out live me
> anyway. I only use it for DXing and contesting mostly. I use it with an
OMNI 6+,
> great combination.
>
>
> ------------------------------
>
> Message: 11
> Date: Wed, 18 Aug 2004 19:13:47 EDT
> From: DennisKT5D@aol.com
> Subject: [TenTec] High performance radios
> To: tentec@contesting.com
> Message-ID: <24.5e1fbac2.2e553cab@aol.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> I really love amateur radio. Been at it for over 35 years. Started
out
> as a novice and have never fallen out of love with CW. I consider myself a
> casual CW DXer and contester. I also enjoy building modest things of my
own
> design (I am an electrical engineer). I think of myself as a decent
operator who
> has never really aspired to win contests but only to enjoy the experience.
In
> short, I am not a high performance operator, which is okay by me.
Therefore, do
> I really need a high performance radio if I already have one that meets my
> current needs? No. I should first hone my skills or set a new direction
for
> enjoying my hobby. I presently do not need nor could I effectively utilize
a high
> performance radio to it's full capabilities. A new ORION (I have an OMNI
6+)
> will not enhance my current satisifaction with amateur radio unless I am
> willing to work to improve my abitility to match it's capability.
> It's much the same way with cameras. An old friend of mine runs a
> camera shop. His advice to the serious amatuer user is to buy a camera
that is
> more capable than your current skill set, then work to improve your skills
to
> match the camera. I think that sometimes we confuse new technology with
> automaticially enhanced skills.
>
>
> ------------------------------
>
> Message: 12
> Date: Wed, 18 Aug 2004 19:16:05 -0400
> From: "Tommy" <aldermant@alltel.net>
> Subject: Re: TT Re: [TenTec] Ten Tec amps and ALC
> To: <tentec@contesting.com>
> Message-ID: <001701c48579$56d05f50$498366a6@w4bqf2>
> Content-Type: text/plain; charset="iso-8859-1"
>
> A word of caution about ALC....do not EVER think ALC completely protects
the
> grids of your amps tubes. The 'little' problem that ALC has is that it is
> slow. Most radios that use ALC for controlling output power level,
produce
> a very short (microseconds), high level RF spike, until the ALC circuit
can
> grab hold of it and bring it back down to a 'regulated' level. More that
one
> pair of 3cx800a7's have mysteriously failed, and investigation showed the
> HUGE RF spike (300-500 watts) present on the leading edge of the RF
waveform
> going to the amp, be it SSB, digital, or CW. If you want to be sure, check
> your xmtr's RF output waveform with a scope, running at about 10
> microseconds per division. Otherwise just replace expensive grid driven
> tubes, which seem to fail for no apparent reason. The Eimac suggested
> replacement, 3cpx800a7, is supposed to be more rugged in this
> respect....just in case one would need new tubes.
>
> Tom - W4BQF
>
> ----- Original Message -----
> From: "Stuart Rohre" <rohre@arlut.utexas.edu>
> To: <tentec@contesting.com>
> Sent: Wednesday, August 18, 2004 6:37 PM
> Subject: TT Re: [TenTec] Ten Tec amps and ALC
>
>
> > An overdrive indicator on an amplifier seems an excellent feature, to
> avoid
> > the possible non-compatibility of ALC circuits in light of no universal
> ALC
> > standard.
> > -Stuart
> > K5KVH
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
>
>
> ------------------------------
>
> Message: 13
> Date: Wed, 18 Aug 2004 17:22:24 -0600
> From: <al_lorona@agilent.com>
> Subject: RE: TT Re: [TenTec] Ten Tec amps and ALC
> To: <tentec@contesting.com>
> Message-ID:
> <03449D1344E4414EB9AAB797FEEADE81015DFBAA@wcosmb01.cos.agilent.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> Tommy,
>
> Is this 500 W spike that "most radios" produce always there? If so, then
what protects the grids of the tubes in the PA under normal operation?
>
> Or maybe I don't understand exactly which radios have this spike problem.
Are there modern radios in this category?
>
> Al W6LX
>
>
>
> > -----Original Message-----
> > From: tentec-bounces@contesting.com
> > [mailto:tentec-bounces@contesting.com]On Behalf Of Tommy
> > Sent: Wednesday, August 18, 2004 4:16 PM
> > To: tentec@contesting.com
> > Subject: Re: TT Re: [TenTec] Ten Tec amps and ALC
> >
> >
> > A word of caution about ALC....do not EVER think ALC
> > completely protects the
> > grids of your amps tubes. The 'little' problem that ALC has
> > is that it is
> > slow. Most radios that use ALC for controlling output power
> > level, produce
> > a very short (microseconds), high level RF spike, until the
> > ALC circuit can
> > grab hold of it and bring it back down to a 'regulated'
> > level. More that one
> > pair of 3cx800a7's have mysteriously failed, and
> > investigation showed the
> > HUGE RF spike (300-500 watts) present on the leading edge of
> > the RF waveform
> > going to the amp, be it SSB, digital, or CW. If you want to
> > be sure, check
> > your xmtr's RF output waveform with a scope, running at about 10
> > microseconds per division. Otherwise just replace expensive
> > grid driven
> > tubes, which seem to fail for no apparent reason. The Eimac suggested
> > replacement, 3cpx800a7, is supposed to be more rugged in this
> > respect....just in case one would need new tubes.
> >
> > Tom - W4BQF
> >
> > ----- Original Message -----
> > From: "Stuart Rohre" <rohre@arlut.utexas.edu>
> > To: <tentec@contesting.com>
> > Sent: Wednesday, August 18, 2004 6:37 PM
> > Subject: TT Re: [TenTec] Ten Tec amps and ALC
> >
> >
> > > An overdrive indicator on an amplifier seems an excellent
> > feature, to
> > avoid
> > > the possible non-compatibility of ALC circuits in light of
> > no universal
> > ALC
> > > standard.
> > > -Stuart
> > > K5KVH
> > >
> > >
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
>
> ------------------------------
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>
> End of TenTec Digest, Vol 20, Issue 77
> **************************************
>
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