[BC] Power efficiency vs transmission quality

[Robert Meuser]

I have worked with J Fred, he even stayed at my house at one time and I 
respect his accomplishments. However, the 317B was way before his time. 
It is a linear amplifier driven by a 316B. There is no way in the world 
a 316B comes close in the modulation category to a 317C series. Trust me 
I ran both at the same time. This is not even a close call. The 316B was 
also a power hog. It was three 4cx5000s screen modulated, no Doherty 
technology.  The linear to make 50 KW was a Doherty but the combination 
does not even run close to the 317 C package in either modulation or 
efficiency.  It was also possibly the most deadly TX package ever built. 
I would not agree that the 317 C-3 was as good as it got for a tube TX. 
I would prefer the MW-50C series, which had the solid state mod driver. 
I had 317 C 2s and worked very closely with Joe Sainton who did many 
mods on them. We jokingly called them 317 2.5 as they got as close as 
you could to a C-3 without extreme surgery. I bought an MW50 C series 
for another station after doing a real world head to head comparison.

R


Milton R. Holladay Jr. wrote:

> According to J. Fred, the B and C had about the same overall 
> efficiency, but
> I've never looked it up to check....And modulation was no problem with 
> good
> tubes. A mod to bypass the input xfmr would have made it free of audio 
> iron.
>  Of course, the 317C-3 was as good as it got in tube 50s.
> The main consideration about tube boxes is whether it was a GOOD xmtr, 
> or a
> POS. Some of the 50 year old tube xmtrs were a lot better than the 30 
> year
> old tube transmitters.
> M
> ----- Original Message -----
> From: "Robert Meuser" <Robertm at broadcast.net>
> To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
> Sent: Tuesday, February 20, 2007 11:05 AM
> Subject: Re: [BC] Re:1 5/8 foam coax
>
>
> > That being said, in the specific case given in the thread a  317B was
> > installed in 1992.   That design was replaced in 1966 but a much more
> > efficient design. Since that time newer technologies have replaced 
> that.
> > So more than even age, we are talking about something that is three
> > design cycles old at the time of install. We are talking about 
> something
> > that takes up much more space, uses much more power and requires much
> > more cooling than newer designs. Then after all that it does not
> > modulate nearly as well as newer designs.  Power consumption is a
> > significant cost factor at 50 kw.
> >
> >
> > Age of a TX is not always important as an absolute number. For 
> example a
> > 27 year old Amphet TX would be reasonable to keep on air if you can
> > still find the transistors. It is not the newest design but it is
> > reasonably close if you really need to save the money, that is if it 
> has
> > been reasonably maintained over the years.
> >
>
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