[Amps] Amplifier Input Circuit Consultation
k7rdx at charter.net
Thu Oct 23 15:47:24 EDT 2008
A pair of 4-1000`s in gg (screens,grids grounded) cathode impedance looks
close to 50 ohms but still needs pi tuned input networks for each band. I
did this way back in the early 70`s and an impedance transformer is not
required. A pair drive very easily,especially with 6-7kv from a well current
rated hvps..It`s a good idea to run seperate adjustable bias to balance the
tubes and prevent one tube from pulling more zsac than the other..GL,73
----- Original Message -----
From: "Paul Kraemer" <elespe at lisco.com>
To: <n1wr at chesapeake.net>; <amps at contesting.com>
Sent: Thursday, October 23, 2008 12:18 PM
Subject: Re: [Amps] Amplifier Input Circuit Consultation
> Sounds fantastic to me!
> Of course, there is an option---use two 4-1000 in paralell, that lowers
> input impedance to 50 ohms.
> It has been done.
> Paul K0UYA
> ----- Original Message -----
> From: <n1wr at chesapeake.net>
> To: <amps at contesting.com>
> Sent: Thursday, October 23, 2008 12:03 PM
> Subject: [Amps] Amplifier Input Circuit Consultation
>>I continue to work on the design/construction of my 4-1000 amplifier. I'm
>> working on the input network details.
>> The 4-1000 has a generally accepted input impedence of 100 ohms. So I am
>> planning on using a 2:1 step up unbalanced to unbalanced balun followed
>> a parallel tuned circuit, Q of 2-3, for each band. Taking this approach
>> will need only one relay contact per band to switch each tuned circuit
>> opposed to two needed to switch a pi network).
>> In all of my reading and research I haven't seen this approach taken.
>> grid compartment is under construction. Before I go ahead and construct
>> the input this way - can anyone come up with a reason this won't work?
>> I thoroughly enjoy this list and faithfully tune in to the goings on. I
>> really appreciate the help and support that is provided.
>> Wayne N1WR
>> Amps mailing list
>> Amps at contesting.com
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> Amps at contesting.com
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