> 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
> KNOW.
>
> End of rant!
>
> 73/jeff/ac0c
When I was gainfully employed I could often bring the latest and best of HP
home for the weekend...got 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 (-;
Carl
KM1H
>
>
> --------------------------------------------------
> From: "Carl" <km1h@jeremy.mv.com>
> Sent: Sunday, May 23, 2010 11:34 AM
> To: <Gudguyham@aol.com>; <ranchorobbo@gmail.com>; <amps@contesting.com>
> 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,
>> km1h@jeremy.mv.com 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?
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
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