As regards the source of this energy, I'd like to solicit the thoughts of
others (including yourself). I'm not sure how much harmonic energy (ala
Fourier) is present in the waveforms appearing at the anode. I've just never
looked at the waveform, but given the conduction angle, there would be even
and odd partials in the series expansion and their relative magnitudes
could be estimated from the coefficients, and these would be the source of
the higher frequency energy. Not so?
Again, I've never looked into this, so I'm very happy to learn if I'm wrong,
or to be pointed to a text for 'remedial reading'.
(Regarding the lead vest, 20+ years ago another engineer and I were aligning
a CRT according to the manufacturers alignment instructions and the very
last instruction on the last page was "be sure to wear a lead apron while
performing this alignment." true story.)
Much obliged
Ed N1TS
----- Original Message -----
From: "R. Measures" <r@somis.org>
To: "Ed Briggs" <edbriggs@optonline.net>; <TexasRF@aol.com>;
<vk6apk@eon.net.au>; "AMPS" <Amps@contesting.com>
Sent: Wednesday, March 03, 2004 10:14 AM
Subject: Re: [Amps] 2 x 8877
>
>
> >But what about at 100 mHz and 200 mHz?
>
> ** Ed-- What is the source of such energy? Using a cellphone would
> seemingly provide more field strength at a more-dangerous-to-corneas
> wavelength. Perhaps the amplifier builder should provide an shield-vest
> to visitors in the shack like the kind dentists used to wear in days past?
>
> >I worry that a) there is no
> >filtering of harmonic energy through the windows (no pi network), and
that
> >the inverse square law is significant when the antenna is 100 feet away
and
> >an vacuum tube admirers corneas are inches away.
> >
> >I have never measured this, though many years ago I did perform part 15
EMI
> >testing on communications equipment and discovered that small rectangular
> >slots passed lots of RF energy.
> >
> >73s
> >Ed N1TS
> >'Festooned with fingerstock and nickel paint"
> >----- Original Message -----
> >From: "R.Measures" <r@somis.org>
> >To: <TexasRF@aol.com>; <vk6apk@eon.net.au>; "AMPS" <Amps@contesting.com>
> >Sent: Tuesday, March 02, 2004 3:24 PM
> >Subject: Re: [Amps] 2 x 8877
> >
> >
> >>
> >>
> >> >Whoa, wait a minute! That 150cm by 100 cm opening might be a waveguide
> >> >beyond
> >> >cutoff but the attenuation for this size opening is pretty low
according
> >to
> >> >the Bill Orr Radio Handbook.
> >>
> >> ** My guess is that, at 28MHz, the radiation from the antenna is at
> >> least 30db stronger than that from the window. .
> >> >
> >> >The chart for this size opening shows a constant attenuation from
about
> >> >1000mhz and lower frequencies on the order of 8db per inch. If the
metal
> >> >is .125
> >> >inches thick then the attenuation is on the order of only one db!
> >> >
> >> >When the opening is reduced to .125 inches the attenuation is on the
> >order
> >> >of
> >> >124 db per inch from about 2000mhz and down. With that level of
> >> >attenuation a
> >> >.125 inch thick screen would have about 30db of through loss.
> >> >
> >> >Cutoff means there is signal attenuation, not a total loss of
> >transmission.
> >> >
> >> >73 de K5GW
> >> >
> >> _______________________________________________
> >> Amps mailing list
> >> Amps@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >
> >
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