[BC] Power efficiency vs transmission quality

[Brian Urban]

Robert
Why do you call the 317B a deadly box?  I was way too intimate with the
final cabinet (rebuilt the air plenum about 5 times)--didn't think it was
any more dangerous than any other high power beast.


On 2/23/07 9:53 AM, "Robert Meuser" <Robertm at broadcast.net> wrote:

> 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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> 
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-- 
Brian Urban
Chief Operator
KUT Radio
The University of Texas at Austin
TEL 512-471-1085
CELL 512-940-4757