Amps
[Top] [All Lists]

Re: [Amps] The dilemma of Tx tube

To: "Jim Thomson" <jim.thom@telus.net>
Subject: Re: [Amps] The dilemma of Tx tube
From: "Carl" <km1h@jeremy.mv.com>
Date: Thu, 2 Aug 2012 14:44:25 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
----- Original Message ----- 
From: "Jim Thomson" <jim.thom@telus.net>
To: "Carl" <km1h@jeremy.mv.com>; "Rob Atkinson" <ranchorobbo@gmail.com>
Cc: <amps@contesting.com>
Sent: Thursday, August 02, 2012 9:41 AM
Subject: Re: [Amps] The dilemma of Tx tube


>
>
> -----Original Message----- 
> From: Carl
> Sent: Thursday, August 02, 2012 5:51 AM
> To: Rob Atkinson ; Jim Thomson
> Cc: amps@contesting.com
> Subject: Re: [Amps] The dilemma of Tx tube
>
> And Jims "assumptions" that a 4-1000A always has poor IMD is just plain
> wrong. In AB1 grid driven start off with a set of Ians tetrode boards or
> similar before assuming anything.
> In GG it will be about 5-6dB better if you get the input network working
> properly.
>
> Carl
> KM1H
>
> ###  Forget AB-1.   I never did  see a 4-1000 in AB-1.
>  What did you measure  for IMD on a 4-1000 in GG.

**  At 4200-5000V about -32dB measured against a 2 tone with decent rolloff 
at the others. IOW about 3-4dB worse than a 3-500Z but still respectable.



> My tuned inputs were dead on back then.  They consisted
> of Millen 69046 tuneable slugs  + silver mica's.   One per band,
> and bandswitched.  The tuned inputs  for 80-15m  were next to the socket.


** Low VSWR doesnt mean squat if the Q is too low, the 4X1 likes around 4-5. 
Its also easy to get false readings with just a single adjustment as often 
seen with Heath amps and then the core cooks.


> Every SA plot I saw depicted lousy IMD.  Any 3-500Z amp was better than a
> GG  4-1000.

** Ive seen a lot of jabbering but only one actual plot and that was a tired 
pull that was being beat into compression.
Maybe it was that ARRL one, dont remember.


>
> ##  back then, nobody ran that tube at 1200w out and  3 kv.


** Those that obeyed the FCC did and Id say that was the majority since 110V 
primary surplus iron was common from BC-610's and similar which ran 3000V 
with a big cap.  Some used SB-220 iron which was cheap direct from Heath. 
They also ran air variables and 850A/850-160 tank coils.

I just picked up a nice 850A for $30 and have a spare contact so I can add 
160. It should do good on AM with that NIB 4PR1000A I got for $10 2 years 
ago.
Then I can retire the 2x HK354C amp, remove the variac from its and the 
modulators PS and finally put that Gates mod iron to use.

Carl


>
> Jim  VE7RF
>
>
>
>
> ----- Original Message ----- 
> From: "Rob Atkinson" <ranchorobbo@gmail.com>
>
> Eimac issued engineering newsletter FCJ-59D2 superseding 59B5 which
> set forth an exception for the 4-1000A as a high mu triode provided Ep
> is at least 3 KV.  It listed typical operating conditions.
>
> 73
>
> Rob
> K5UJ
>
>
>
> On Thu, Aug 2, 2012 at 3:15 AM, Jim Thomson <jim.thom@telus.net> wrote:
>> Date: Wed, 1 Aug 2012 19:37:39 -0500
>> From: Rob Atkinson <ranchorobbo@gmail.com>
>> Subject: Re: [Amps] The dilemma of Tx tube
>>
>> The eimac triode connected g.g. cathode driven data sheet for the 4x1
>> has specifications for 3, 4 and 5 KV.
>>
>> Rob
>> K5UJ
>>
>> On Wed, Aug 1, 2012 at 4:07 PM, <Gudguyham@aol.com> wrote:
>>>
>>> If I am not mistaken, the 4X1 "typical" GG service is rated at 3KV. Pump
>>> it up with the proverbial "pole pig" power supply at 6KV and something 
>>> has
>>> to go out of spec. Most likely IMD?
>>
>>
>> ##  If you looked at any Eimac catalog  from the  1960-1995,  you WON’T
>> see  any GG  specs for a 4-1000.  I mean with screen + grid  bonded to 
>> chassis, and
>> run as a high MU triode.    Einac did list some GG  specs for hams
>> in the odd rag  like CQ  once in a while... like for 3-4-5 kv.   That was 
>> just a courtesy
>> thing.  No ham was gonna buy a brand new Eimac 4—1000 anytime soon.  For 
>> less  money,
>> you could buy a NEW 3-1000Z.... which IS   rated for GG, and also rated 
>> up to 6 kv in GG.
> _______________________________________________
> 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: 10.0.1424 / Virus Database: 2437/5172 - Release Date: 08/02/12
>
>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1424 / Virus Database: 2437/5172 - Release Date: 08/02/12
> 

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>