[Boatanchors] TX4C problem

[Bill Abate]

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
> 
> 
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