[Boatanchors] TX4C problem

[D C _Mac_ Macdonald]

At rated output of the AC-4 at 650V and CATHODE (plate + screen) current of 350 mA you should be running about 200 W or just a bit more of plate input power.  Generally, you can expect 120 W output on 80 - 10, with maybe 110 W on 15m and 100 W on 10m with "fresh" output tubes. 
 
I'd say running at 270 W is a guarantee short life of the final tubes! 
  
* * * * * * * * * * * 
* 73 - Mac, K2GKK/5 * 
* (Since 30 Nov 53) * 
* k2gkk hotmail com * 
* Oklahoma City, OK * 
* USAF & FAA (Ret.) * 
* * * * * * * * * * * 
 

> Date: Sun, 1 Mar 2015 23:29:28 -0500
> From: wabate at verizon.net
> To: k4oah at mindspring.com
> CC: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] TX4C problem
> 
> Garey,
> 
> The dummy load is fine.  There is negligible reflected power.  The power 
> input is about 270 watts.  So its about 60% efficiency if the Bird is 
> right.  I have no reason to doubt it as it tracks with other wattmeters 
> and what I would expect from my other rigs.  The efficiency does appear 
> high.  I'm not too concerned as I use the numbers as a benchmark only to 
> gauge when things are going south.  My meters are not NBS traceable! :)
> 
> 73,
> 
> Bill, K3PGB
> 
> Garey Barrell wrote:
> 
> > Bill -
> > 
> > Yes, the 6EJ7 is an 'iffy' tube, even NOS.
> > 
> > You should check your dummy load...  those are pretty excessive output 
> > powers for a T-4XC, and would translate into almost 500 mA of plate 
> > current.  Consider Drake specified a MAX of 350 mA on most bands.  Or, 
> > how much reflected power do you measure with the Bird?
> > 
> > 73, Garey - K4OAH
> > Glen Allen, VA
> > 
> > Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
> > and TR-4/C Service Supplement CDs
> > <www.k4oah.com>
> > 
> > Bill Abate wrote:
> > 
> >> Bill,
> >>
> >> My T-4XC needed a 6EJ7.  After an alignment I got 150 to 165 watts 
> >> into a dummy load measured with my Bird wattmeter on all bands. That 
> >> 6EJ7 made a big difference.  Not sure why yours is so low but the 
> >> finals seem to be a good candidate.  Also I found a NOS tube did not 
> >> help the problem when it should have.  When all else fails don't rely 
> >> on a single tube sub.  Check RF voltage at the 6JB6's grid on each band.
> >>
> >> 73,
> >>
> >> Bill, K3PGB
> >>
> >> Bill and Liz wrote:
> >>
> >>> I have been playing with a drake TX4C and, after going through the
> >>> complete alignment process a couple of times, a strange problem
> >>> persists.  I believe the PA tubes to be weak-power output on 10M is
> >>> around 50W in CW mode.  But the radio makes 90W on 160M in spite of
> >>> the fact that there is not enough C in the loading cap and about the
> >>> same on 80M where the loading cap does peak nicely.
> >>>
> >>> However, on 40M there appears to be considerably more drive available
> >>> and power output runs 130W at about 375 ma which I read as being
> >>> normal.  It is less on 20 and 15-around 90W or so output.  I see only
> >>> a bit of power sag key down on 10M.
> >>>
> >>> Can anyone suggest why there is so much more drive on 40M?  Is this
> >>> condition characteristic of the TX4 series?
> >>>
> >>> Bill VE3NH