[BC] Power efficiency vs transmission quality

[Robert Meuser]

Actually the driver part is the deadly part. If you recall many 
important adjustments were inside the interlocked cabinet. You had to 
bypass the safeties to adjust these properly. I saw someone electrocuted 
doing just that. It used to make me very nervous when I had to tweak 
that box.

R



Brian Urban wrote:

>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.
>>>>
>>>>        
>>>>