On the subject of auxiliary transmitter on ...
I worked in the broadcast business for over 40 years. Mostly as a Chief
or Consultant to many radio stations. Multiple TVs, etc. I only one case
did we keep the wick lit on the aux, and that was very early on, say '60s.
If the backup is lit up and there is a power surge two transmitters are
down.
The incremental cost of the tube or some parts being on isn't worth
shortened
life.
Exciters terminated in a tube that's not "on" but just lit results
in "packed grids" which may take hours to clean out. If the condition lasts
long enough kiss the drivers good bye. Now you have no spare transmitter at
all.
I did however in the 70's and 80's keep the exciters running, terminated in
a dummy load. Turning filaments on drops the relay and the exciter feeds the
driver.
Kinda simple, but I'm a simple guy.
You could be back on air in little more than a minute with #2 dark, whats
the deal?
If management is that concerned about outages, run 2 lower powered
transmitters
in parallel, then you only have a 6 db loss immediately, switching the
combiner
and your only down 3 db with the single transmitter.
Of course, never tried parallel transmitters on AM. Bet tuning that puppy
would
be fun ...
Ed K0KL
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of amps-request@contesting.com
Sent: Friday, September 08, 2006 10:07 PM
To: amps@contesting.com
Subject: Amps Digest, Vol 45, Issue 21
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Today's Topics:
1. Re: NOS 4CX1000A test and reconditioning (Dan Hearn)
2. Re: [1000mp] 1000MP Power Supplies (Harold Mandel)
3. Re: NOS 4CX1000A test and reconditioning (Mike Manship)
4. amp tubes (carl s.)
5. Re: NOS 4CX1000A test and reconditioning (Tom W8JI)
6. Re: NOS 4CX1000A test and reconditioning (Paul Christensen)
7. Ferromagnetic Core Design & Application Handbook (Will Matney)
8. Re: NOS 4CX1000A test and reconditioning (Joe Subich, W4TV)
9. Re: NOS 4CX1000A test and reconditioning (Robert B. Bonner)
10. Re: NOS 4CX1000A test and reconditioning (Robert B. Bonner)
11. Re: NOS 4CX1000A test and reconditioning (Paul Christensen)
----------------------------------------------------------------------
Message: 1
Date: Fri, 8 Sep 2006 09:19:53 -0700
From: "Dan Hearn" <dhearn@air-pipe.com>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: "Hsu" <Jbenson@sohu.com>, <amps@contesting.com>
Message-ID: <ACEGINBFNLHLHJAHIHCPIEPGDAAA.dhearn@air-pipe.com>
Content-Type: text/plain; charset="us-ascii"
Good information here. http://kk5dr.com/Tubes.html
73, Dan, N5AR
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of Hsu
Sent: Wednesday, September 06, 2006 5:14 AM
To: amps@contesting.com
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
PS,I want to how to test and recondition thoriated tungsten tube ex. 4X500A
too.Thanks!
73! Hsu
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------------------------------
Message: 2
Date: Fri, 8 Sep 2006 15:36:25 -0400
From: "Harold Mandel" <ka1xo@juno.com>
Subject: Re: [Amps] [1000mp] 1000MP Power Supplies
To: "'All about Yaesu 1000mp'" <1000mp@mailman.qth.net>,
<amps@contesting.com>
Message-ID: <00bf01c6d37e$1392ddd0$050ca8c0@laptopHM>
Content-Type: text/plain; charset="us-ascii"
Here's another great find for you-all with
Astron linear supplies that are worried about
poor regulation and capacitor breakdown:
JEA CAPACITORS, a store on e-bay.com,
run by Jacques Ebert, (Capacitor12).
He has absolutely new computer grade capacitors
in stock and shipped out four of the 35,000uF / 80 WVDC
and got them to me from NY to SC in three days via
UPS Brown.
Packaging superb, product flawless, prices rock bottom.
Hal Mandel
W4HBM
------------------------------
Message: 3
Date: Fri, 8 Sep 2006 13:36:48 -0400
From: Mike Manship <mjmanship@iquest.net>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: amps@contesting.com
Message-ID: <1157737008.4501aa30b0230@webmail.iquest.net>
Content-Type: text/plain; charset=ISO-8859-1
Quoting Dan Hearn <dhearn@air-pipe.com>:
> Good information here. http://kk5dr.com/Tubes.html
> 73, Dan, N5AR
>
One of the "facts" stated on this web page is that broadcast
stations keep all their final amplifier tubes filaments powered
at all times. I used to work at a broadcast station with
three transmitters and we only had the filaments powered to the
transmitter in use. Were we the only one ?
73 de Mike W9OJ
------------------------------
Message: 4
Date: Fri, 08 Sep 2006 17:45:20 -0400
From: "carl s." <carlseye@tampabay.rr.com>
Subject: [Amps] amp tubes
To: "Amps@contesting.com" <Amps@contesting.com>
Message-ID: <4501E470.3040507@tampabay.rr.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I have been working on an amp, fl2100B , and see something I can't
believe.!! the amp has 2 ea. New chinese type 572B's.
I have two output meters, both WM1 auteks.; With about 60-80 watts
input I'm seeing almost 1 kw. *output*. Is this anywhere near logical
?? The HV is about 2200-2300 under load. !! It just doesn't seem
possible, and I've never seen anything like this
before !!!
I've worked on many other amps ( similar ) and have never seen
anything like that much output.!!
BUT, I've never used *chinese* 572'B s either !!
Do any of you have any spec's that might differ from the
U S. ( IE ) taylor ,l or other mfrs. Specs as to the gain factors
between the US and chinese specs'?????>
I'd appreciate any info anyone might have !!!!!
carl / kz5ca
------------------------------
Message: 5
Date: Fri, 8 Sep 2006 20:35:09 -0400
From: "Tom W8JI" <w8ji@w8ji.com>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: "Mike Manship" <mjmanship@iquest.net>, <amps@contesting.com>
Message-ID: <002b01c6d3a7$d6303300$640fa8c0@radioroom>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
> One of the "facts" stated on this web page is that
> broadcast
> stations keep all their final amplifier tubes filaments
> powered
> at all times. I used to work at a broadcast station with
> three transmitters and we only had the filaments powered
> to the
> transmitter in use. Were we the only one ?
>
> 73 de Mike W9OJ
I worked at three stations and consulted for dozens more and
none of them had the filaments on all the time. What I've
seen agrees with what you have seen.
73 Tom
------------------------------
Message: 6
Date: Fri, 8 Sep 2006 19:38:31 -0400
From: "Paul Christensen" <w9ac@arrl.net>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: "Mike Manship" <mjmanship@iquest.net>, "Amps Amps"
<amps@contesting.com>
Message-ID: <002c01c6d39f$e4fd63b0$72163405@Dorm>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
> One of the "facts" stated on this web page is that broadcast
> stations keep all their final amplifier tubes filaments powered
> at all times. I used to work at a broadcast station with
> three transmitters and we only had the filaments powered to the
> transmitter in use. Were we the only one ?
When I was in the broadcast business, I do not recall that being standard
practice -- even in major markets where funding is not an issue. Sure,
there may be a few stations that have tried it, but the benefit does not
offset the long-term result. In fact, the practice of leaving the filament
continuously heated in an FM transmitter in which ceramic tubes are employed
can result in severe de-tuning over time at VHF frequencies.
I know of one well-known broadcast engineer in the Chicago market who
documented the effect and presented a paper in the Proceedings during a
1970s NAB convention. In the case presented, a long-term filament-on
condition without HV and excitation resulted in semi-conductive deposits
forming on the inner ceramic of the tube. In one demonstrated case, a pair
of 4CX250B tubes used as the IPA in a Harris FM-20H transmitter had failed
after several weeks in the this condition which first manifest as a gradual
detuning of the IPA to PA stage. Finally, IPA tuning was no longer possible
owing to the contamination of the tube. The test was repeated several times
with identical results.
Since most commercial broadcast transmitters use directly-heated cathodes,
warm-up time is not much of an issue. Many transmitters use time-delays
that far exceed what is required in order to apply excitation to the PA and
IPA. That said, glass tubes used at HF may fare better than the example
described above, but the cost v. benefit cannot be justified even in the
most intensely competitive major markets.
Paul, W9AC
------------------------------
Message: 7
Date: Fri, 08 Sep 2006 21:54:32 -0400
From: "Will Matney" <craxd1@verizon.net>
Subject: [Amps] Ferromagnetic Core Design & Application Handbook
To: amps@contesting.com
Message-ID: <200609082154320070.0ABA8AA0@outgoing.verizon.net>
Content-Type: text/plain; charset=ISO-8859-1
All,
I ran across the book titled "Ferromagnetic Core Design & Application
Handbook"
by Doug DeMaw on ebay. I have this book and it is a good one about the
design of RF
transformers and chokes using ferrite cores. There's 23 hours to go.
Link;
http://cgi.ebay.com/Ferromagnetic-Core-Design-Application-Handbook-Demaw_W0Q
QitemZ290025630744QQihZ019QQcategoryZ378QQrdZ1QQcmdZViewItem
Item: 290025630744
------------------------------
Message: 8
Date: Fri, 8 Sep 2006 21:46:15 -0400
From: "Joe Subich, W4TV" <w4tv@subich.com>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: "'Mike Manship'" <mjmanship@iquest.net>, "'amps'"
<amps@contesting.com>
Message-ID: <00c301c6d3b1$bfab6230$0b80a8c0@laptop>
Content-Type: text/plain; charset="us-ascii"
> One of the "facts" stated on this web page is that broadcast
> stations keep all their final amplifier tubes filaments powered
> at all times. I used to work at a broadcast station with
> three transmitters and we only had the filaments powered to the
> transmitter in use. Were we the only one ?
I have been Director of Engineering at four different television
stations, had corporate responsibility for additional stations and
visited countless transmitter sites over 20+ years. In every case
where there the station had alternate/main and/or "back-up"
transmitters, the filaments were kept live so the back-up could
go on the air instantly.
73,
... Joe, W4TV
------------------------------
Message: 9
Date: Fri, 8 Sep 2006 21:50:59 -0500
From: "Robert B. Bonner" <rbonner@qro.com>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: <amps@contesting.com>
Message-ID: <005101c6d3ba$c83349a0$4dcf6f18@cd0209633033>
Content-Type: text/plain; charset="US-ASCII"
Well now what? I built this big test rack last night and have 2 3-500's, 6
8877/YU-158's, 3 3CX3000A7's, 2 YC-156's an 8938 heated up.
The 14 12AX7's look pretty cool - fans running everywhere
All my amps are running at idle - Man I had to unplug my Hot Tub.
SO we aren't going to do that now?
Actually some of that info is good, especially running the filament over
night before applying HV and going for the smoke test.
My Henry 432 cavity with the 8938 was new just out of the crate but had been
in storage for almost 15 years without being run. I ran it up over night,
then hooked up the B+ let it idle for several hours to get used to having
juice on it... Then brought it up to a couple hundred watts... Let it
cool.. Brought it up to 1000 and cool (filli running the whole time)
finally 1500 and then 2000 I got scared at that point, figured my brain
might cook. BOB DD
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Tom W8JI
Sent: Friday, September 08, 2006 7:35 PM
To: Mike Manship; amps@contesting.com
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
> One of the "facts" stated on this web page is that
> broadcast
> stations keep all their final amplifier tubes filaments
> powered
> at all times. I used to work at a broadcast station with
> three transmitters and we only had the filaments powered
> to the
> transmitter in use. Were we the only one ?
>
> 73 de Mike W9OJ
I worked at three stations and consulted for dozens more and
none of them had the filaments on all the time. What I've
seen agrees with what you have seen.
73 Tom
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------------------------------
Message: 10
Date: Fri, 8 Sep 2006 22:02:44 -0500
From: "Robert B. Bonner" <rbonner@qro.com>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: "'Amps Amps'" <amps@contesting.com>
Message-ID: <005201c6d3bc$6c6c0a10$4dcf6f18@cd0209633033>
Content-Type: text/plain; charset="US-ASCII"
I think we're going to have to admit that both methods are in use, filaments
on or off.
It all depends on the Attitude of the chief and the mentality of the owners.
Can you live with a 10 minutes of on the air silence?
While I was still in college in 75 I was on the phone trying to get a
Collins 20T back online after a plate choke left. I'm 135 miles away and my
buddy the DJ who was also the resident license holder is in the bottom of
the transmitter with a set of clip leads and a VOM. That station didn't
have their backup even hooked up nor tested.
Me personally I'd test a backup transmitter on a Sunday morning once a
month. Switch the thing off the rest of the time. Less obtrusive than an
EBS test HA.
BOB DD
------------------------------
Message: 11
Date: Fri, 8 Sep 2006 22:53:00 -0400
From: "Paul Christensen" <w9ac@arrl.net>
Subject: Re: [Amps] NOS 4CX1000A test and reconditioning
To: <pegasus@mho.net>, "Amps Amps" <amps@contesting.com>
Message-ID: <015f01c6d3bb$103dd2b0$72163405@Dorm>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
> reduced voltage during the hours the transmitter was dark. I think it
> was something like 80% of normal voltage. They claimed it improved
> filament life by both avoiding the startup stresses as well as the wear
> of full power on the filament when not needed. (not to mention less
> power consumption) I don't know if this was ever put in to common
> practice, but I know it was used in some circles.
As I recall, a filament reduction to 80% is useful as "black heat" and some
high-power commercial transmitters have the ability to go into a black heat
mode during extended standby periods. This may be what Joe is referring to
with television transmitter experiencess. It makes perfect sense during
events like "Superbowl Sunday" with so much at stake, but in the AM/FM
broadcast side of the world, I think you would be hard-pressed to find many
stations that run their auxiliary transmitters in a hot-standby mode on a
regular basis.
Reducing filament E on a directly-heated cathode to below ~ 70% of the
normal operating value is like turning the filament off as phase transitions
in the filament structure reduce tube life as filament E drops below this
value.
Paul, W9AC
------------------------------
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End of Amps Digest, Vol 45, Issue 21
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