[Collins] 30S-1

[Carl]

What were the test parameters?

Carl


----- Original Message ----- 
From: "David Knepper" <collinsradio at comcast.net>
To: "Carl" <km1h at jeremy.mv.com>; "Alan Chandler" 
<alanchandler at frontier.com>; "collins" <collins at mailman.qth.net>
Sent: Monday, September 20, 2010 8:32 PM
Subject: Re: [Collins] 30S-1


> FYI - this test was conducted several years ago and appeared in an early 
> issue of the Collins Journal prepared by Warren Bruene.
>
> David Knepper, W3CRA/W3ST
> Editor of the Collins Journal
> Secretary of the Collins Radio Association
> www.collinsra.com
> Join today
> ----- Original Message ----- 
> From: "Carl" <km1h at jeremy.mv.com>
> To: "Alan Chandler" <alanchandler at frontier.com>; "collins" 
> <collins at mailman.qth.net>
> Sent: Monday, September 20, 2010 3:47 PM
> Subject: Re: [Collins] 30S-1
>
>
>>I hope you use a dynamic signal to run the IMD tests which better compares
>> to real world than a steady state 2 tone.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message ----- 
>> From: "Alan Chandler" <alanchandler at frontier.com>
>> To: "collins" <collins at mailman.qth.net>
>> Sent: Monday, September 20, 2010 1:28 PM
>> Subject: [Collins] 30S-1
>>
>>
>>> The 30S-1 is one of the lowest IMD amplifiers ever produced for amateur
>>> use.
>>> It uses a grounded screen grid and operates the cathode at about -200
>>> volts
>>> as the screen supply.  The RF drive is supplied to the cathode so the RF
>>> adds about 100 volts to the cathode which results in a total screen 
>>> supply
>>> of about 300 volts when fully driven.  The Eimac 4CX1000A maximum screen
>>> voltage is 400 so adding 125 volts to the screen supply will exceed the
>>> maximum rating under RF drive.  Typical AB1 operation for the 4CX1000A 
>>> is
>>> with 325 volts on the screen which is about where the 30S-1 actually
>>> operates.  Increasing the screen voltage does increase the gain of the
>>> tube, requiring less drive power but it reduces the available plate
>>> voltage swing before the screen current rises to the level that exceeds
>>> the screen dissipation (35ma at 325v is just under 12 watts,
>>> the maximum screen dissipation.)  and the tube is in saturation. The net
>>> result can be more output power but with a substantial increase in IMD.
>>> You will typically get about 1 to 2 dB increase in power (0.2 to .04 S
>>> units) and about 10 dB higher IMD (2 S units).  Be kind to operators on
>>> adjacent frequencies and leave the screen supply where it was designed 
>>> to
>>> be operated.
>>>    I have just about finished setting up a variable screen supply and 
>>> will
>>> make power and IMD measurements with a 4CX1000A and 4CX1500B in a 30S-1
>>> later in the fall.  I started the project in the Spring but good weather
>>> forced yard work to take precedence.  When I complete this, the results
>>> will be sent to The Signal.
>>>
>>> 73, Alan - K6RFK
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>