[Amps] Amps Digest, Vol 135, Issue 32
Bob Gunther
kg4ojz at hotmail.com
Wed Mar 26 15:51:36 EDT 2014
As far as the 50 volt power supply, You'd need about 50 amps for a for a 1,000 watt amplifier. (Class A/B efficiency). I am looking for a similar supply, but I'm leery of all the pin-outs. Most require a feedback loop for sampling the voltage, a 5 volt status line, and a remote on/off line.
I can never find any real documentation for these server supplies. Meanwell in China builds supplies that will work, but they are expensive. http://www.trcelectronics.com/Meanwell/power-supply-pfc-rsp2000.shtml It would be ok to parallel two supplies to get the current from 2 smaller supplies, but I would put rectifiers after the output and before i combine them.
Bob NM1Z
Director of Engineering
WOAY-TV-ABC
Bluefield/Beckley/Oak Hill, WV market
> From: amps-request at contesting.com
> Subject: Amps Digest, Vol 135, Issue 32
> To: amps at contesting.com
> Date: Wed, 26 Mar 2014 08:24:10 -0400
>
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> Today's Topics:
>
> 1. HV limit for rfc-3 choke? (Rich Hallman - N7TR)
> 2. Re: HV limit for rfc-3 choke? (Carl)
> 3. Re: HV limit for rfc-3 choke? (Alek Petkovic)
> 4. Re: HV limit for rfc-3 choke? (peter chadwick)
> 5. Re: More on Toroidal Tank Circuit Issues (Jim W7RY)
> 6. Re: HV limit for rfc-3 choke? (Leigh Turner)
> 7. 50 V high current power supplies (David Kirkby)
> 8. Re: 50 V high current power supplies (Chris Wilson)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 25 Mar 2014 18:06:43 +0000
> From: Rich Hallman - N7TR <rich at n7tr.com>
> To: amp reflector <amps at contesting.com>
> Subject: [Amps] HV limit for rfc-3 choke?
> Message-ID: <297546FA-27BB-4EDB-A74C-FDFB6920C02C at n7tr.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Will the rfc-3 choke work at 5kv? I know they say 4kv, but wanted to know if others are using it at higher voltages?
>
> Thanks.... Rich N7TR
>
> ------------------------------
>
> Message: 2
> Date: Tue, 25 Mar 2014 16:30:39 -0400
> From: "Carl" <km1h at jeremy.mv.com>
> To: "Rich Hallman - N7TR" <rich at n7tr.com>, "amp reflector"
> <amps at contesting.com>
> Subject: Re: [Amps] HV limit for rfc-3 choke?
> Message-ID: <AA2F4AEC6CE94F70BF2EB3AEDE78C515 at computer1>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> I know people using them at 5KV from a 4-1000 to 3CX3000; they appear to
> hold up but I wouldnt want to experiment on RTTY with the 3X3 or bigger..
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Rich Hallman - N7TR" <rich at n7tr.com>
> To: "amp reflector" <amps at contesting.com>
> Sent: Tuesday, March 25, 2014 2:06 PM
> Subject: [Amps] HV limit for rfc-3 choke?
>
>
> > Will the rfc-3 choke work at 5kv? I know they say 4kv, but wanted to
> > know if others are using it at higher voltages?
> >
> > Thanks.... Rich N7TR
> > _______________________________________________
> > Amps mailing list
> > Amps at contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
> >
> > -----
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>
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 26 Mar 2014 06:12:07 +0800
> From: Alek Petkovic <vk6apk at bigpond.com>
> Cc: amp reflector <amps at contesting.com>
> Subject: Re: [Amps] HV limit for rfc-3 choke?
> Message-ID: <5331FF37.2070809 at bigpond.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Dunno what 'the rfc-3 choke' is but if it is the Ameritron plate
> choke,that we all use in our homebrew amps, I'm running it at 6kV in a
> YC-156 amp. I never knew that it had a limit/rating on it. Sometimes,
> ignorance is bliss.
>
> Alek. VK6APK
>
> On 26/03/2014 4:30 AM, Carl wrote:
> > I know people using them at 5KV from a 4-1000 to 3CX3000; they appear
> > to hold up but I wouldnt want to experiment on RTTY with the 3X3 or
> > bigger..
> >
> > Carl
> > KM1H
> >
> >
> > ----- Original Message ----- From: "Rich Hallman - N7TR" <rich at n7tr.com>
> > To: "amp reflector" <amps at contesting.com>
> > Sent: Tuesday, March 25, 2014 2:06 PM
> > Subject: [Amps] HV limit for rfc-3 choke?
> >
> >
> >> Will the rfc-3 choke work at 5kv? I know they say 4kv, but wanted
> >> to know if others are using it at higher voltages?
> >>
> >> Thanks.... Rich N7TR
> >> _______________________________________________
> >> Amps mailing list
> >> Amps at contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >>
> >>
> >> -----
> >> No virus found in this message.
> >> Checked by AVG - www.avg.com
> >> Version: 2014.0.4354 / Virus Database: 3722/7241 - Release Date:
> >> 03/24/14
> >>
> >
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>
> --
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> http://www.qrz.com/db/vk6ap
>
> Family Businesses:
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> ------------------------------
>
> Message: 4
> Date: Tue, 25 Mar 2014 23:18:14 +0100
> From: peter chadwick <g8on at fsmail.net>
> To: Carl <km1h at jeremy.mv.com>, Rich Hallman - N7TR <rich at n7tr.com>,
> amp reflector <amps at contesting.com>
> Subject: Re: [Amps] HV limit for rfc-3 choke?
> Message-ID: <10486968.28311395785894770.JavaMail.www at wwinf3719>
> Content-Type: text/plain; charset=UTF-8
>
> Figure it this way:
>
> Suppose you have 5kV DC and a plate swing of 8kV p-p or 2800 RMS. 225 microhenries is 2545 ohms at 1.8 MHz so the RF current in the choke is 1.1 amps, in addition to the DC. If Q = 100, R = 25 ohms and the power loss in the choke becomes 30 watts. That 1.1 amps needs a low impedance ground return, so that means something of the order of maybe 5nF to ground. Larger values can get too inductive on the higher bands... Even then, 5nF is 17 ohms at 1.8 MHz, so there will be about 20 volts of RF at the base of the choke. That means you need another choke and capacitor to keep RF away from the HV electrolytics.
>
> I recently published an article in the journal of the Vintage and Military Amateur Radio Society on this: I can send a copy if anyone has any interest.
>
> 73
>
> Peter G3RZP
> ========================================
> Message Received: Mar 25 2014, 08:30 PM
> From: "Carl" <km1h at jeremy.mv.com>
> To: "Rich Hallman - N7TR" <rich at n7tr.com>, "amp reflector" <amps at contesting.com>
> Cc:
> Subject: Re: [Amps] HV limit for rfc-3 choke?
>
> I know people using them at 5KV from a 4-1000 to 3CX3000; they appear to
> hold up but I wouldnt want to experiment on RTTY with the 3X3 or bigger..
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Rich Hallman - N7TR" <rich at n7tr.com>
> To: "amp reflector" <amps at contesting.com>
> Sent: Tuesday, March 25, 2014 2:06 PM
> Subject: [Amps] HV limit for rfc-3 choke?
>
>
> > Will the rfc-3 choke work at 5kv? I know they say 4kv, but wanted to
> > know if others are using it at higher voltages?
> >
> > Thanks.... Rich N7TR
> > _______________________________________________
> > Amps mailing list
> > Amps at contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
> >
> > -----
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 2014.0.4354 / Virus Database: 3722/7241 - Release Date: 03/24/14
> >
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 25 Mar 2014 21:36:08 -0700
> From: "Jim W7RY" <w7ry at centurytel.net>
> To: <Undisclosed-Recipient:;>
> Cc: AMPS <amps at contesting.com>
> Subject: Re: [Amps] More on Toroidal Tank Circuit Issues
> Message-ID: <2B631DB2453D46F58E5DA4BF4CDA7380 at JimsLaptop>
> Content-Type: text/plain; format=flowed; charset="UTF-8";
> reply-type=original
>
> So here is the real fix!
>
> I removed the 80 and 160 meter toroids all together. Installed a 2" dia X
> 3.5" long ceramic coil with 42 turns of #14 wire and hooked it to the end of
> the 40 meter coil. The new coil is perpendicular to the 20-40 meter coil.
>
> Works perfectly! No more 10 meter heating! And on 80 meters, with lots of
> keydown at 1600 watts out, the coil gets to about 125 degrees F, and on 160
> a little less. But I normally don?t run RTTY on 160 meters. As of yet, all
> RTTY contests are on 80-10.
>
> The best bet will be to find a ceramic coil or just the coil-form that I can
> wind with #12 or #10 wire. 10 is probably a bit too big. I guess I could
> wind 80 meters with #10 and 160 meters with #12. I really want to stay with
> a ceramic coil-form to keep it from deforming like a air-dux coil would.
>
> I know Carl has a ceramic form on the auction site but it too is wound with
> #14 wire.
>
> Anyone have a 2" (and it must not be more than 2-1/4" X 5 or 6 inch long
> ceramic coil-form with grooves for winding? It has to have at least 36
> grooves for 36 turns of wire.
>
> This has been an interesting experiment to say the least!
>
> Thanks all
> 73
> Jim W7RY
>
>
> -----Original Message-----
> From: Jim W7RY
> Sent: Saturday, March 22, 2014 1:25 PM
> To: Dan Hearn
> Cc: AMPS
> Subject: Re: [Amps] More on Toroidal Tank Circuit Issues
>
> So I used the measurement technique from Tom W8JI that he has on his site
> and found that the 160 meter toroid was certainly resonate on 10 meters! No
> matter what I did. Sure, I could move my hand around the toroid and get the
> the lamp to dim and sometimes go out. But there didn?t seem to be any place
> moving the windings that would help.
> http://www.w8ji.com/rf_plate_choke.htm
>
>
> So..... I made a center tap on the 160 meter toroid and simply shorted it to
> one end with a normally closed vacuum relay. I open the relay only on 160
> meters.
>
> See here:
> http://s900.photobucket.com/user/w7ry/media/8877%20Amplifier/IMG_0250_zps17bca129.jpg.html?sort=3&o=0
>
> Seems to work just great. No arcing or sparking. As you can see, the leads
> are pretty long and the relay is just taped to the Plexiglas. I used the
> bench power supply to energize the relay on 160. There was no interaction
> with anything. Even had the lid off when testing 160 meters.
>
> The toroid seems to run perfectly cool (about a 10 degree temperature rise
> on 10 meters measuring with my Fluke IR thermometer) when operating on all
> bands. Tuning seemed better and more power output with less drive and lower
> plate current for the same output power (1600 watts) on 10 meters just like
> removing the toroid all together.
>
> I'm going to move the 160 meter toroid back to where it was, and move it
> further from the load vacuum cap. If I had it to do over again, I would have
> mounted the caps closer to the outside walls to give me more room to work
> between them.
>
> I?ll also have to wire up the relay to energize on 160 meters. Rather than
> tie into the tuned input switching, I?ll just put another switch contact
> between the front panel and the sub panel.
>
>
> 73
> Jim W7RY
>
>
>
>
>
> From: Dan Hearn
> Sent: Friday, March 21, 2014 5:47 PM
> To: Jim W7RY
> Cc: AMPS
> Subject: Re: [Amps] More on Toroidal Tank Circuit Issues
>
> Jim, I would try a small air wound coil similar to what you would use in a
> parasitic suppressor in series with the toroid, maybe in the lead to the
> switch.
>
>
> Dan, N5AR
>
>
>
>
> On Fri, Mar 21, 2014 at 4:46 PM, Jim W7RY <w7ry at centurytel.net> wrote:
>
> Both leads are shored by the band switch when on 10 meters guys.
> Interesting that 3 of you came up with the same possibility...
>
> Not sure where to put the capacitor if both leads are shorted together.
> Perhaps I could center tap the toroid (bare the Teflon wire) and solder a
> cap from the center tap to one of the output leads.
>
> I removed the toroid and the major heat in the 3 turns of wire is where
> the winding is within 1/4 inch of the vacuum loading cap. Which is probably
> to close.
> See:
> http://s900.photobucket.com/user/w7ry/media/8877%20Amplifier/P1010217.jpg.html?sort=3&o=16
>
> I was simply going to move it away from the loading cap and see what
> happens. I was also thinking of install a wire coil. I have a ceramic coil
> form that would work. 30 turns, 2?dia 3.5? long which is 20uH. I have room
> to mount this.
>
> Thanks all!
> 73
> Jim W7RY
>
>
> From: Dan Hearn
> Sent: Friday, March 21, 2014 3:02 PM
> To: Jim W7RY
> Cc: AMPS
> Subject: Re: [Amps] More on Toroidal Tank Circuit Issues
>
> Jim, I think your 160 toroid when shorted is self resonant with its
> distributed capacitance on 10m. You might be able to solve this by putting
> a small cap across the 160 m toroid to move its self resonance.
>
>
> 73, Dan, N5AR
>
>
>
>
> On Fri, Mar 21, 2014 at 1:08 PM, Jim W7RY <w7ry at centurytel.net> wrote:
>
> I may have to eat some crow here about using dedicated toroids on 160
> and 80 meters...
>
> I built an 8877 amplifier based on the K8RA (SK) 3CX1500D7 amplifier.
> http://www.k8ra.com/index_049.htm
>
> Mine is shown here:
> http://s900.photobucket.com/user/w7ry/media/8877%20Amplifier/DSC_0037.jpg.html?sort=3&o=47
>
> And here:
> http://s900.photobucket.com/user/w7ry/media/8877%20Amplifier/P1010225.jpg.html?sort=3&o=13
>
> The lower toroid is 160 only and the upper one is 80 meters only (with
> 10,15,20 and 40 coils added in of course).
>
> I?m using a shorting band switch 6 position.
>
>
> On 10 meters, the 160 meter toroid (lower one) gets so hot, the
> fiberglass tape has turned brown, and the Teflon wire is melting the
> Plexiglas that the toroid's are mounted on.
>
> I know all about trying to use a tapped toroid for multiple bands is
> wrong (except on the L coil of the Pi-L circuit, and see my postings about
> the Commander HF-2500 and K1TTT?s pictures of same) but WHY is the 160 meter
> toroid getting so hot when using 10 meters? It's mounted very close to the
> loading vacuum capacitor is the only thing that I can think of. But the
> weird part, is that this just started. During all of the testing, there was
> no problem, but now, its really getting HOT!
>
> When testing, I had the top cover off of the amplifier, now that I?m
> using it, the top cover is on. I?m going to try the test again with the top
> off and see what happens.
>
> On 80 and 160 meters, the toroids are normal temperature (around 100
> degrees) and everything works just fine since I?m not shorting turns on the
> toroids.
>
> Ideas?
> Thanks and 73
> Jim W7RY
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
>
> --
> Dan Hearn
> N5AR
>
>
>
>
> --
> Dan Hearn
> N5AR
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
> ------------------------------
>
> Message: 6
> Date: Wed, 26 Mar 2014 15:43:06 +1030
> From: "Leigh Turner" <invertech at frontierisp.net.au>
> To: <amps at contesting.com>
> Subject: Re: [Amps] HV limit for rfc-3 choke?
> Message-ID: <F588A817B71D44439EB190F53980872F at Invertech>
> Content-Type: text/plain; charset="us-ascii"
>
>
> Excellent figuring Peter!
>
> An additional choke and bypass cap is almost essential to prevent
> deleterious 1.8 MHz RF blow-by into the HV power supply electrolytics.
>
> Mind you the HV "glitch" resistor also provides some attenuation of RF
> leakage when bypassed with a ceramic cap.
>
> Leigh
> VK5KLT
>
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of peter chadwick
> Sent: Wednesday, 26 March 2014 8:48 AM
> To: Carl; Rich Hallman - N7TR; amp reflector
> Subject: Re: [Amps] HV limit for rfc-3 choke?
>
> Figure it this way:
>
> Suppose you have 5kV DC and a plate swing of 8kV p-p or 2800 RMS. 225
> microhenries is 2545 ohms at 1.8 MHz so the RF current in the choke is 1.1
> amps, in addition to the DC. If Q = 100, R = 25 ohms and the power loss in
> the choke becomes 30 watts. That 1.1 amps needs a low impedance ground
> return, so that means something of the order of maybe 5nF to ground. Larger
> values can get too inductive on the higher bands... Even then, 5nF is 17
> ohms at 1.8 MHz, so there will be about 20 volts of RF at the base of the
> choke. That means you need another choke and capacitor to keep RF away from
> the HV electrolytics.
>
> I recently published an article in the journal of the Vintage and Military
> Amateur Radio Society on this: I can send a copy if anyone has any interest.
>
> 73
>
> Peter G3RZP
>
> ========================================
> Message Received: Mar 25 2014, 08:30 PM
> From: "Carl" <km1h at jeremy.mv.com>
> To: "Rich Hallman - N7TR" <rich at n7tr.com>, "amp reflector"
> <amps at contesting.com>
> Cc:
> Subject: Re: [Amps] HV limit for rfc-3 choke?
>
> I know people using them at 5KV from a 4-1000 to 3CX3000; they appear to
> hold up but I wouldnt want to experiment on RTTY with the 3X3 or bigger..
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Rich Hallman - N7TR" <rich at n7tr.com>
> To: "amp reflector" <amps at contesting.com>
> Sent: Tuesday, March 25, 2014 2:06 PM
> Subject: [Amps] HV limit for rfc-3 choke?
>
>
> > Will the rfc-3 choke work at 5kv? I know they say 4kv, but wanted to
> > know if others are using it at higher voltages?
> >
> > Thanks.... Rich N7TR
> > _______________________________________________
>
>
>
>
>
>
> ------------------------------
>
> Message: 7
> Date: Wed, 26 Mar 2014 11:53:35 +0000
> From: David Kirkby <david.kirkby at onetel.net>
> To: Amps at contesting.com
> Subject: [Amps] 50 V high current power supplies
> Message-ID:
> <CANX10hD97MAHT6Rv+6Ao3usbEu3jet9APMB3M_dGAt4W9rnkdA at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Someone in my local radio club is looking for a 50 V PSU for a
> home-brew linear he is thinking of making. I don't know exactly what
> power he is looking at, but I assume an put power of 1000 or more
> Watts would be needed, which is at least 20 A at 50 V. I believe there
> are some surplus HP or Compaq computer supplies around this voltage
> that some have used. Can anyone suggest any particular models that
> work well?
>
> Dave
>
>
> ------------------------------
>
> Message: 8
> Date: Wed, 26 Mar 2014 12:23:58 +0000
> From: Chris Wilson <chris at chriswilson.tv>
> To: Amps at contesting.com
> Subject: Re: [Amps] 50 V high current power supplies
> Message-ID: <166603411.20140326122358 at chriswilson.tv>
> Content-Type: text/plain; charset=us-ascii
>
>
>
> Hello David,
>
> On Wednesday, March 26, 2014, you wrote:
>
> > Someone in my local radio club is looking for a 50 V PSU for a
> > home-brew linear he is thinking of making. I don't know exactly what
> > power he is looking at, but I assume an put power of 1000 or more
> > Watts would be needed, which is at least 20 A at 50 V. I believe there
> > are some surplus HP or Compaq computer supplies around this voltage
> > that some have used. Can anyone suggest any particular models that
> > work well?
>
> > Dave
>
> I use these, various sources have these from time to time, on Ebay:
>
> http://www.ebay.co.uk/itm/HP-253232-001-BL20p-3000W-PSU-POWER-SUPPLY-/300908478716?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWAX%3AIT&nma=true&si=GQSUwXvo4QAuOLLWEcib%252BSw%252FgTk%253D&orig_cvip=true&rt=nc
>
>
>
> --
> Best regards,
> Chris mailto:chris at chriswilson.tv
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
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> Amps mailing list
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> http://lists.contesting.com/mailman/listinfo/amps
>
>
> ------------------------------
>
> End of Amps Digest, Vol 135, Issue 32
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