----- 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.
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