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[Amps] i was reading on here

To: "amps@contesting.com" <amps@contesting.com>
Subject: [Amps] i was reading on here
From: Kevin Adam <n9iww@LIVE.COM>
Date: Thu, 8 Dec 2016 03:53:03 +0000
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Down At Dayton this year Palstar came out with LDMOS dual BLF578 amp they were 
waiting FCC acceptance of it.
N9IWW

-----Original Message-----
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Sent: Wednesday, December 7, 2016 10:32 PM
To: amps@contesting.com
Subject: Amps Digest, Vol 168, Issue 37

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Today's Topics:

   1. Re: SS amps and auto-tune. Is it even necessary? (Leigh Turner)
   2. Re: Pulls? (RAY FRIESS)
   3. Re: Pulls? (Jeff AC0C)
   4. Re: SS amps and auto-tune. Is it even necessary? (qrv@kd4e.com)
   5. Re: SS amps and auto-tune. Is it even necessary? (Leigh Turner)


----------------------------------------------------------------------

Message: 1
Date: Thu, 8 Dec 2016 11:11:50 +1030
From: "Leigh Turner" <invertech@frontierisp.net.au>
To: "'AMPS'" <amps@contesting.com>
Cc: <leigh.turner@ieee.org>
Subject: Re: [Amps] SS amps and auto-tune. Is it even necessary?
Message-ID: <9876C98E73CE419A91C28B9E4D9EF638@Invertech>
Content-Type: text/plain;       charset="iso-8859-1"


I agree with the spot-on-the-mark sentiment summary expressed below. 

A very fine QRO legal-limit S.S. amp with decent IMD specs can be homebrewed by 
the savvy hands-on experimentally inclined (not many of us left?) amongst the 
ham radio fraternity.

Jim is right about the complexity and cost of "everything else" particularly 
implementing the requisite diplexer based harmonic terminating auto-switched HF 
multi-band LPF capable of handling up to 2.5 kW under potentially high VSWR 
conditions. In terms of dollars per Watt the modern LDMOS FET active devices 
per se are very cheap.

If one is designing a monoband S.S. QRO amp then some complexity and associated 
cost savings can be had.

Adequate heatsinking and dealing with the demanding thermal issues (the 
Achilles heel of LDMOS and MOSFET RF power devices) and efficient heat 
extraction is the other principal challenge. This has a big impact on 
semiconductor MTBF.

It can all be done; but not cheaply :-(

Cheap, reliable / good MTBF, no time limit QRO, low IMD, are mutually exclusive 
design goals. The pragmatist has to take their pick which parameters they value 
most; choosing them all is an expensive exercise even for the resourceful 
homebrewer; commercially we are talking over $10K ++ for a high-end S.S. 
amplifier. 

Leigh
VK5KLT

-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Catherine James
Sent: Thursday, 8 December 2016 3:45 AM
To: amps@contesting.com; Jim Thomson
Subject: Re: [Amps] SS amps and auto-tune. Is it even necessary?

On Wed, 12/7/16, Jim Thomson <jim.thom@telus.net> wrote:

 ##? The low cost of the LDMOS is the least of the issues involved.???Its 
everything else that?s involved with the SS amp. 
 ##  Jim???VE7RF
 
Yep, that's it in two sentences.  That's why I can't get excited about cheap SS 
finals until I see a complete, commercialized SS amp using them, said amp to be 
affordable and reliable. Right now they are for experimenters.

73,
Cathy
N5WVR
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------------------------------

Message: 2
Date: Thu, 8 Dec 2016 00:44:18 +0000
From: RAY FRIESS <rayfrijr@msn.com>
To: "amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps] Pulls?
Message-ID:
        
<DM5PR01MB2746FEAD9434342366587049CA840@DM5PR01MB2746.prod.exchangelabs.com>
        
Content-Type: text/plain; charset="iso-8859-1"

Speaking of pulls ..   I was a broadcast engineer about 35 years ago and we 
would regularly pull tubes when they were down to about 90% of their rated 
readings in the transmitter.  We would throw them out and replace them with new 
ones, until I started saving the pulls and taking them home.

As a result, I have about a dozen 4-125 and 4-250 tubes which were primarily 
used in the modulator section of our 5 KW transmitter.   They have been in 
storage at my home ever since and are still, for all intents and purposes, 
brand new.  They look brand new even, considering that they were replaced when 
they were at 85 to 90% efficiency.  I kept them thinking they would work great 
for ham linears for anyone who was building a linear.


If there is any interest, let me know.....   Most of them I rewrapped in their 
original padding and put back in their original boxes and stored in a safe 
place.


________________________________
From: Amps <amps-bounces@contesting.com> on behalf of Catherine James 
<catherine.james@att.net>
Sent: Wednesday, December 7, 2016 9:50 AM
To: amps@contesting.com
Subject: Re: [Amps] Pulls?

And how do you find these deals when broadcast stations with older transmitters 
do a pull?

I hear a lot of discussion around how great pulls are as an affordable source 
of good tubes, but it is always vague and never tells us how we can get in on 
the fun.  Is this one of those "you have to know somebody" situations?

73,
Cathy
N5WVR

--------------------------------------------
On Wed, 12/7/16, Fuqua, Bill L <wlfuqu00@uky.edu> wrote:

 Subject: RE: [Amps] Pulls?
 To: "Catherine James" <catherine.james@att.net>
 Date: Wednesday, December 7, 2016, 4:25 AM

   Most pulls today are from broadcast stations using older transmitters. Also, 
from SK estates.
 73
 Bill wa4lav
 ________________________________________
 From:
 Amps [amps-bounces@contesting.com]
 on behalf of Catherine James [catherine.james@att.net]
 Sent: Tuesday, December 06, 2016 11:13 PM
 To: Amps Group
 Subject: [Amps]
 Pulls?

 Where do you guys get your tube pulls?

 I see many, many mentions of pulls from medical or other devices,  but I have 
never seen these offered. Have they dried up? Or  do they all go up on eBay at 
crazy prices?

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Amps Reflector - Contesting.com Ham Radio Mailing 
Lists<http://lists.contesting.com/mailman/listinfo/amps>
lists.contesting.com
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 
...




------------------------------

Message: 3
Date: Wed, 7 Dec 2016 20:31:11 -0600
From: "Jeff AC0C" <keepwalking188@ac0c.com>
To: <amps@contesting.com>
Subject: Re: [Amps] Pulls?
Message-ID: <A9A474FCFCA34787A1D21DD0A06D9917@w520>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
        reply-type=original

I don't think PULL has a generic meaning.  How can you generalize with so many 
different tubes in so many different applications and with different thresholds 
for determining when to swap?  You can find stories on both ends - success and 
fail.

My only experience with pulls is with some YC156 that K5AND Dick sent to me to 
test in my amp as he was thinking about selling those.  I have a new
(NOS) tube here for reference and 3 out out of the 4 pulls exhibited exactly 
the same power output with exactly the same Ig as the new tube.  I don't know 
how much "life" would be left in them from a ham amp standpoint but they were 
100% as far as I could determine.  The 4th had some sort of internal short.  My 
experience with the YC156 pulls is pretty good based on this single data point.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message-----
From: RAY FRIESS
Sent: Wednesday, December 07, 2016 6:44 PM
To: amps@contesting.com
Subject: Re: [Amps] Pulls?

Speaking of pulls ..   I was a broadcast engineer about 35 years ago and we 
would regularly pull tubes when they were down to about 90% of their rated 
readings in the transmitter.  We would throw them out and replace them with new 
ones, until I started saving the pulls and taking them home.

As a result, I have about a dozen 4-125 and 4-250 tubes which were primarily 
used in the modulator section of our 5 KW transmitter.   They have been in 
storage at my home ever since and are still, for all intents and purposes, 
brand new.  They look brand new even, considering that they were replaced when 
they were at 85 to 90% efficiency.  I kept them thinking they would work great 
for ham linears for anyone who was building a linear.


If there is any interest, let me know.....   Most of them I rewrapped in 
their original padding and put back in their original boxes and stored in a 
safe place.


________________________________
From: Amps <amps-bounces@contesting.com> on behalf of Catherine James 
<catherine.james@att.net>
Sent: Wednesday, December 7, 2016 9:50 AM
To: amps@contesting.com
Subject: Re: [Amps] Pulls?

And how do you find these deals when broadcast stations with older 
transmitters do a pull?

I hear a lot of discussion around how great pulls are as an affordable 
source of good tubes, but it is always vague and never tells us how we can 
get in on the fun.  Is this one of those "you have to know somebody" 
situations?

73,
Cathy
N5WVR

--------------------------------------------
On Wed, 12/7/16, Fuqua, Bill L <wlfuqu00@uky.edu> wrote:

Subject: RE: [Amps] Pulls?
To: "Catherine James" <catherine.james@att.net>
Date: Wednesday, December 7, 2016, 4:25 AM

   Most pulls today are from broadcast stations using older transmitters. 
Also, from SK estates.
73
Bill wa4lav
________________________________________
From:
Amps [amps-bounces@contesting.com]
on behalf of Catherine James [catherine.james@att.net]
Sent: Tuesday, December 06, 2016 11:13 PM
To: Amps Group
Subject: [Amps]
Pulls?

Where do you guys get your tube pulls?

I see many, many mentions of pulls from medical or other devices,
but I have never seen these offered. Have they dried up? Or
do they all go up on eBay at crazy prices?

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
Amps Reflector - Contesting.com Ham Radio Mailing 
Lists<http://lists.contesting.com/mailman/listinfo/amps>
lists.contesting.com
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 ...


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------------------------------

Message: 4
Date: Wed, 7 Dec 2016 22:14:24 -0500
From: "qrv@kd4e.com" <qrv@kd4e.com>
To: 'AMPS' <amps@contesting.com>
Subject: Re: [Amps] SS amps and auto-tune. Is it even necessary?
Message-ID: <5848D010.5010901@kd4e.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I respectfully disagree - unless one demands only a
full-legal amp.

SB-200's (and many similar power-level amps) sold like
crazy in the past & are still being resold daily.

A 600w SS amp is not expensive to build - a 1.5KW is.

Might we divide the discussion that way, please?

It would be helpful to direct some attention to the
positive opportunities via new devices to provide Hams
with affordable entry-level 160-10m SS amps.

WDYT?

Thanks - David KD4E

> It can all be done; but not cheaply :-(
>
> Leigh VK5KLT




------------------------------

Message: 5
Date: Thu, 8 Dec 2016 14:01:30 +1030
From: "Leigh Turner" <invertech@frontierisp.net.au>
To: "'AMPS'" <amps@contesting.com>
Subject: Re: [Amps] SS amps and auto-tune. Is it even necessary?
Message-ID: <1902DA76358F4F0EBC154A12B4209A7A@Invertech>
Content-Type: text/plain;       charset="us-ascii"


Yes, fully agree David; if we bifurcate the S.S. amp design and build
endeavour to less than 600 Watt PEP, and no time limit 1.5 kW, then it's an
entirely different ballgame whereby things become very doable at a price
entry-level hams can afford.

Leigh
VK5KLT

-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of qrv@kd4e.com
Sent: Thursday, 8 December 2016 1:44 PM
To: 'AMPS'
Subject: Re: [Amps] SS amps and auto-tune. Is it even necessary?

I respectfully disagree - unless one demands only a
full-legal amp.

SB-200's (and many similar power-level amps) sold like
crazy in the past & are still being resold daily.

A 600w SS amp is not expensive to build - a 1.5KW is.

Might we divide the discussion that way, please?

It would be helpful to direct some attention to the
positive opportunities via new devices to provide Hams
with affordable entry-level 160-10m SS amps.

WDYT?

Thanks - David KD4E

> It can all be done; but not cheaply :-(
>
> Leigh VK5KLT


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------------------------------

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