[Yaesu] Mark V Field Power Output Mod

[Joe Subich, K4IK]

It's hardly a guess since every advertisement, the brochure on 
Yaesu's US web site and the brochure/specifications on Yaesu's 
far east web site all say 100 Watts.  The only place 200 Watts 
is even mentioned is Yaesu.co.uk.  Even at Yaesu.co.uk, the 
narrative (page 1) of the Field information starts: 

 > Conservative 100W Low Distortion Final Amplifier Design
 >
 > The Field utilizes a pair of high-dissipation 2SC2879 
 > bipolar transistors in a push-pull design, driven by 
 > push-pull 2SC3133s, yielding a low-distortion 100- Watt 
 > transmitter compatible with the Class-A operation 
 > capability pioneered on the MARK-V FT-1000MP. These 
 > transistors are run well below their rated output, and 
 > are utilized in conjunction with pure local oscillator 
 > signals and time-proven low-pass filter designs, to 
 > provide you with the cleanest signal on the band! During 
 > Class-A operation, SSB power output becomes 25 Watts, and 
 > transmitter intermodulation products will be significantly 
 > better than Class AB.
  
If Yaesu had respecified the Field for 200 Watts, even if 
unofficially, you would see every vendor trumpeting that 
information.  Typo is almost a certainty. 

In fact, here is the Toshiba 2SC2897 spec sheet web: 

   http://www.qsl.net/df7tv/datasheets/2SC2879.pdf

While the transistor is rated to 100 Watts, it shows substantial 
non-linearity (> 1 dB gain compression) above 80 watts.  Best 
(lowest) IMD occurs in the vicinity of 60 Watts output (120 Watts 
for a pair).  At 100 watts the IMD is worse than -24 dB.  

The point is ... 200 Watts (or even 150 Watts) from a Field 
is completely irresponsible.  With only a $310 difference in 
the retail price, to risk blowing the final amplifier transistors 
or increased IMD with a Field is the hallmark of the immature 
persons who illegally "hotrod" CB radios.  

73, 

   ... Joe, K4IK 
 



> -----Original Message-----
> From: 1000mp-bounces at mailman.qth.net
> [mailto:1000mp-bounces at mailman.qth.net]On Behalf Of Joe Subich, K4IK 
> Sent: Friday, August 06, 2004 10:42 AM
> To: 'All about Yaesu 1000mp'
> Subject: RE: [1000mp] Re: Mark V Field Power Output Mod
> 
> 
> 
> If you would bother to look at the information on the FT-1000MP/MKV 
> on the same site, you will find identical data for the MKV.  Someone 
> has simply failed to update the specifications when doing a cut and 
> paste. 
> 
> Look at the specification sheet here: 
> 
>  
http://www.yaesu.com/downloadFile.cfm?FileID=675&FileCatID=156&FileName=
MARK%20V%20Field%5FBrochure.pdf&FileContentType=application%2Fpdf  

You will see:  "Adjustable up to 100 Watts
                (25 Watts AM carrier)." 

73, 

   ... Joe, K4IK