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Re: [Amps] How to read the 3-500Z spec sheet?

To: "Jeff Blaine AC0C" <>, <>
Subject: Re: [Amps] How to read the 3-500Z spec sheet?
From: "Carl" <>
Date: Sun, 23 May 2010 20:43:56 -0400
List-post: <">>

> Carl,
> If you don't mind, I want to jump on the soapbox here and mention 
> something.
> In discussions with hams on transmitted spectral purity, I keep hearing "I 
> don't have a SA" and "SA is an expensive box."  This excuse is just not 
> acceptable.
> For the purposes of understanding your transmitted signal, the cost to 
> "gear up" for that can be as little as $25.  How do you do that?
> 1. Buy a single-band Softrock SDR from Tony Parks.  $15 unassembled in kit 
> or about $35 assembled.
> 2. Download the free copy of Scott W2UX PowerSdr-IF-Stage.
> 3. Connect the ouput of the SDR into your PC sound card.  Adjust based on 
> the instructions seen on Scott's site.
> This combination gives you single band coverage with a spectrum width of 
> 48-196 khz, depending on the capabilites of the sound card.  Dynamic range 
> will be a minimum of 70db; and if you have a really nice sound card, maybe 
> as much as 110db.
> Push the transmitter into a dummy load.  Decouple the SDR antenna away 
> from the transmitter coax to ensure you are not clipping the SDR or the 
> sound card.  And what you will see is a representation of the transmitted 
> signal every bit as accurate and valid as a $40K HP SA. Zoom in to your 
> hearts content.  The SDR is very linear over at least a 60db range and 
> that means that even without any absolute calibration to a standard for 
> levels, you can measure the relative levels of the transmitted signal and 
> their IMD products.
> Of course, a real IMD test requires a 2 -tone source and you can download 
> those applications on the web free of charge.  A good quick and dirty 
> solution is to switch your digi mode application over to PSK.  In fact, if 
> it were up to me, it would be a legal requirement for all PSK ops to have 
> station monitors of this type when running PSK.  Lot of misinformation and 
> nonsense in that community among the rookie ops.
> My point here is that in 2010, hams don't need to consult data sheets and 
> handbooks and the wise ones like Carl as to what their beasts should be 
> producing.  They, with minimal effort, can MEASURE IT DIRECTLY and then 
> End of rant!
> 73/jeff/ac0c

When I was gainfully employed I could often bring the latest and best of HP 
home for the real spoiled. But I really do enjoy retirement!

These days I have a 20 year old SA plus lab grade audio generators, tuneable 
filters, RF generators, Class A broadband distributed amps pads, and other 
goodies Ive picked up at local belly up autions. It takes up more room than 
I like but it more than enough does the job.

Im not ready to trust a PC to do any of this yet except run the HPIB 
controller and that software runs on a ancient WIN95 PC! Heck, I even have a 
7550 plotter which I find useful at times (-;


> --------------------------------------------------
> From: "Carl" <>
> Sent: Sunday, May 23, 2010 11:34 AM
> To: <>; <>; <>
> Subject: Re: [Amps] How to read the 3-500Z spec sheet?
>> Try sticking to the 3-500Z and the service in the discussion Lou.
>> You might also want to look at the 3-500Z Eimac specs at the Absolute
>> Maximum Ip rating for Class B linear service.
>> And at some point put an AL-80 on an SA and look at the IMD when operated
>> full bore. It aint pretty.
>> Carl
>> ------------
>> In a message dated 5/23/2010 11:16:53 A.M. Eastern Daylight Time,
>> writes:
>> At 2700V @ 400 ma it doesnt matter if its CCS or not
>> Carl, how do you account for a pulse rating on a tube? For a 3cpx1500a7 
>> tube
>> the plate current is 50AMPS and the Anode V is 10KV and the output power 
>> is
>> 306KW!!  Is it not a Po vs time?
>> _______________________________________________
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