Hello everybody:
Tnx for ur help and information. Now another question:
What should be done to operate de Drake L7 in 10 m band?
73. Alberto, HC2AQ
-----Mensaje original-----
De: Amps [mailto:amps-bounces@contesting.com] En nombre de
amps-request@contesting.com
Enviado el: lunes, 25 de febrero de 2013 9:35
Para: amps@contesting.com
Asunto: Amps Digest, Vol 122, Issue 30
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Today's Topics:
1. Re: Why always one parasitic suppressor per tube? (Carl)
2. Re: 813 efficiency (Carl)
3. Re: 813 efficiency (Carl)
4. 3k plate transformer (Douglas Johnson)
5. Freescale and NXP VHF LDMOS Fets (John Lyles)
6. Re: Why always one parasitic suppressor per tube? (Bill Turner)
7. 813 efficiency (Mike Lord)
8. Re: 813 efficiency (Roger (K8RI))
9. Alpha 9500 Troubles (W3KL)
----------------------------------------------------------------------
Message: 1
Date: Sat, 23 Feb 2013 11:00:58 -0500
From: "Carl" <km1h@jeremy.mv.com>
To: "Bill Turner" <dezrat1242@yahoo.com>, "Amps" <amps@contesting.com>
Subject: Re: [Amps] Why always one parasitic suppressor per tube?
Message-ID: <6603FA84823E4BAB9A931DBCD4884A22@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
----- Original Message -----
From: "Bill Turner" <dezrat1242@yahoo.com>
To: "Amps" <amps@contesting.com>
Sent: Friday, February 22, 2013 8:50 PM
Subject: Re: [Amps] Why always one parasitic suppressor per tube?
> ORIGINAL MESSAGE:
> On Fri, 22 Feb 2013 11:18:14 -0600, Mike wrote:
>
>>Earlier handbooks, etc, show plenty of amps with different tubes with no
>>parasitic suppressor at all, and that's what I'm going to try.
>
> REPLY:
> Remember your oscillator basics: RF energy has to be fed back to the
> input
> circuit in the correct phase to sustain amplification. IMO, the best way
> to
> suppress VHF oscillation is to make the input circuit a very low impedance
> at the frequency of the VHF parasitic tank in the plate circuit. If the
> impedance is low enough, it will swamp out enough RF energy so that the
> tube(s) will not oscillate.
>
> Probably the most important rule in keeping VHF impedance low i to keep
> all
> wiring in the input circuit as short as possible. One of the worst things
> you can do is to run coax from the back of the chassis where the tube is
> up
> to a band switch on the front panel. Sections of coax like this act as a
> transmission line transformer and can exhibit very high impedance at VHF
> frequencies, just what you don't want. Instead, mount the input bandswitch
> right next to the tube socket. Yes, I know this means having two separate
> band switches but it goes a long way toward stabilizing your amp.
>
> I have built several amps with this in mind and NO parasitic suppressor in
> the place circuit. All were unconditionally stable, even with the antenna
> disconnected.
>
> Bill, W6WRT
What were the tubes used besides your 8877 amp?
Carl
KM1H
------------------------------
Message: 2
Date: Sat, 23 Feb 2013 11:07:12 -0500
From: "Carl" <km1h@jeremy.mv.com>
To: <g8on@fsmail.net>, <amps@contesting.com>
Subject: Re: [Amps] 813 efficiency
Message-ID: <54AE544094244A909DA45EB0F00FFCBB@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Oh, I know you can Peter, it is just a lot more complicated and might bring
neutralization into the picture.
I have never read any BC-610 statistics, wonder if they exist. My PP 250TH
Class C amp in the 50's was built around 610 parts and I operated one at the
K0NAB club station in the early 60's, I managed to not get bit by either.
Carl
KM1H
----- Original Message -----
From: "peter chadwick" <g8on@fsmail.net>
To: <amps@contesting.com>
Sent: Saturday, February 23, 2013 8:35 AM
Subject: Re: [Amps] 813 efficiency
> Carl,
> You can switch tank coils in push pull amps!
> I wonder how many people got killed bandchanging a BC610?
> 73
> Peter G3RZP
> _______________________________________________
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> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
> -----
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------------------------------
Message: 3
Date: Sat, 23 Feb 2013 11:09:21 -0500
From: "Carl" <km1h@jeremy.mv.com>
To: "Eddy Swynar" <deswynar@xplornet.ca>, <amps@contesting.com>
Subject: Re: [Amps] 813 efficiency
Message-ID: <5960B071F3FD429B8C73B44A6BB29D7E@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
For about the same money there are still many 4-250A and 400A's available.
Carl
KM1H
> Hi Guys,
>
> It absolutely gobsmacks me how some guys in this hobby would rather
> whip-out the ol' VISA card & spend literally HUNDREDS on power amplifier
> tubes, when the lowly ol' 813---paired with some twins, of course!---will
> do the job as well, and at an absolute FRACTION of the price...
>
> Sure the tube has high interelectrode capacitance, & has been around since
> before WW2: but so what? It's nothing that a bit of 21st century
> technology can't master...and who cares about age? After all, I myself am
> 60 years old here, & hardly consider my existence to be "redundant"! Hi Hi
>
> ~73~ de Eddy VE3CUI - VE3XZ
> _______________________________________________
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> http://lists.contesting.com/mailman/listinfo/amps
>
>
> -----
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> Checked by AVG - www.avg.com
> Version: 10.0.1430 / Virus Database: 2639/5625 - Release Date: 02/23/13
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------------------------------
Message: 4
Date: Sat, 23 Feb 2013 08:35:54 -0800 (PST)
From: Douglas Johnson <w9iix1@yahoo.com>
To: "amps@contesting.com" <amps@contesting.com>
Subject: [Amps] 3k plate transformer
Message-ID:
<1361637354.20674.YahooMailNeo@web120505.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=us-ascii
bought a triad 70400 plate transformer for a henry 3k, it has 4 terminals on
the primary, appears 1-4 are low voltage and 2-3 high voltage, anyone have
the pinout for sure?....tnx, Doug,w9iix
------------------------------
Message: 5
Date: Sat, 23 Feb 2013 09:41:00 -0700
From: John Lyles <jtml@losalamos.com>
To: amps@contesting.com
Subject: [Amps] Freescale and NXP VHF LDMOS Fets
Message-ID: <5128F11C.4070305@losalamos.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
The newest LDMOS high power transistors are being grabbed up by
commercial amplifier production, for HDTV (band II VHF and into UHF) and
FM broadcast amplifiers and for scientific. I didn't mention military,
but I'm sure its there too. For instance, Harris broadcast has been
using the Freescale parts, and had done a lot of development testing for
them. Engineers at Argonne National Laboratory have been developing very
high power solid state units, over 100 kW, using them at 350 MHz. Again,
lots of interaction with the manufacturer to work out the bugs.
Overseas, I have heard from reputable designers who like the NXP 'XR'
better, one story suggesting that the Freescale parts were originally
too nervous and would oscillate at high frequency (UHF/Lband) easily.
In December we took delivery of a first piece of a 5.5 kW pulsed amp at
200 MHz, to use as a predriver. They will eventually replace our six
1995-vintage units used a box full of MRF151G-like devices at 24 VDC,
with linear power supply, 3 phase. These are obsolete amplifiers now, as
the mfr is out of the biz and no longer supports parts. So the new
Communications Power Corporation amp uses (I think) the Freescale LDMOS,
and only needs 8-12 devices compared to 64 of the older DMOS devices at
lower voltage. We are just about to install it to drive the first tetrode.
These new LDMOS transistors are rather costly, comparable with a 3-500Z
for power in a device, more fragile but higher Gain x Bandwidth.
For HF and below, of course, plastic switching MOSFETs are still the
least expensive way to get high power, and can be run above 50 V. You
can see many results on the Class E amplifier Forum online, where a
number of hams are building kW-level modules for AM transmitters with
PDM modulator. Neat stuff!
73
John
K5PRO
> ORIGINAL MESSAGE:
> On Fri, 22 Feb 2013 14:51:36 +0000, Mike wrote:
>
>>
>> Now, this would be interesting but at the same time I'm swapping all my
>> amplifiers out from tubes to BLF578 or MRFE6VP61K25H that need the PSU
>>from (1) above...
>
> REPLY:
> Ok, how about some design info on the above?
>
> A few months ago there was a post about the BLF578XR transistor from NXR.
> Very high power and very resistant to damage. Haven't heard anything
since.
> Is anyone doing anything with this?
>
> There are several YouTube videos on this. Just do a search for BLF578XR.
>
> Bill, W6WRT
------------------------------
Message: 6
Date: Sat, 23 Feb 2013 09:51:41 -0800
From: Bill Turner <dezrat1242@yahoo.com>
To: Amps <amps@contesting.com>
Subject: Re: [Amps] Why always one parasitic suppressor per tube?
Message-ID: <a30ii8d3ggom1aeep1n63rjmnhv5p2gpit@4ax.com>
Content-Type: text/plain; charset=us-ascii
ORIGINAL MESSAGE:
On Sat, 23 Feb 2013 11:00:58 -0500, KM1H wrote:
>
>What were the tubes used besides your 8877 amp?
>
>Carl
>KM1H
REPLY:
The others were all ceramic tetrodes of the 4CX1000 and 4CX1500 family.
Bill, W6WRT
------------------------------
Message: 7
Date: Sat, 23 Feb 2013 14:07:45 -0600
From: "Mike Lord" <k4elv@bellsouth.net>
To: <amps@contesting.com>
Subject: [Amps] 813 efficiency
Message-ID: <7C46D4593D134DAC926A72B890B9E68F@Johns>
Content-Type: text/plain; charset="iso-8859-1"
I just wanted to take a moment to thank all who took the time to respond to
my query. The response was amazing. So much information and ideas were
shared. I feel like I have a much better understanding of the issue.
73 Mike K4ELV
------------------------------
Message: 8
Date: Sat, 23 Feb 2013 15:44:26 -0500
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] 813 efficiency
Message-ID: <51292A2A.2050007@rogerhalstead.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 2/22/2013 8:23 PM, Carl wrote:
> I can just picture todays crop of hams changing tank coils (-; It might
> improve the gene pool tho....
Might be incentive for those remaining to learn at least basic
electronics...Nah, this is the entitlement generation.
The survivors would expect the electrons to learn their lesson and the
family would expect a large settlement from the manufacturer for making
such a dangerous device.
73
Roger (K8RI)
>
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "peter chadwick" <g8on@fsmail.net>
> To: <amps@contesting.com>
> Sent: Friday, February 22, 2013 11:01 AM
> Subject: Re: [Amps] 813 efficiency
>
>
>>
>> Another way is to abandon the pi network and run them in push-pull:
>> this was how quite high efficiencies were obtained on the higher bands
>> 'in the good old days' admittedly, in Class C. That wouldn't be
>> difficult in GG, either - you could use transmission line
>> transformers to get push pull drive.
>> 73
>> Peter G3RZP
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 10.0.1430 / Virus Database: 2639/5623 - Release Date: 02/22/13
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>
> _______________________________________________
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>
------------------------------
Message: 9
Date: Sat, 23 Feb 2013 16:28:56 -0500
From: "W3KL" <w3kl@w3kl.com>
To: <amps@contesting.com>
Subject: [Amps] Alpha 9500 Troubles
Message-ID: <044001ce120c$ca544170$5efcc450$@w3kl.com>
Content-Type: text/plain; charset="US-ASCII"
I have a relatively new Alpha 9500 that clearly is experiencing some
problems:
1) Last weekend I keyed up the rig on 20 m and noticed the power and
grid current LEDs were pegged in the red. The amp immediately faulted with
fault 15 (excessive grid current).
2) This behavior was repeatable and persisted even after I powered down
and then back on.
3) I also had one or two fault 8's when I tried exercising the band
switch.
4) I also saw that the tube was getting hot so I powered down and sent
a message to RF Concepts.
5) They asked me to check to see if the grid current problem persisted
even with no RF drive - it does.
6) When performing these second tests (Thursday) I noticed that the amp
would draw current (about 125 mA) when in the operate mode even when not
keyed up.
7) Finally, last night and this morning I noticed that when the amp is
warming up and I go to Operate mode (flashing green) the tube would start to
draw current (starts at 30 mA and then to 125 mA) as it warms up. Also the
tube was getting very hot (even with blower on).
I suspect a problem with grid voltage supply. However, does anyone else
have ideas?
I have several calls into RF Concepts but they haven't responded yet.
BTW, the amp is only about a year old. I baby it.never hot switch between
bands and it only gets about 8 hours of operating time per week.
Thanks for reading.
73, Jeff
W3KL
------------------------------
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