[Boatanchors] 6146 vs 6146A vs 6146B or 6146W

lee pulsarxp at embarqmail.com
Tue Jul 5 03:25:20 EDT 2011

I just scrutinized the spec sheets for the above mentioned tubes.  They are 
6146, 6146A, and the 6146B or newer 6146W tubes.  The spec sheets show the 
6146B and 6146A  interelectrode capacity to be virtually the same and the 
6146 tube to have 1/2 pf more input capacitance.  So for practical matters, 
the interelectrode capacitances are the same for all these tubes.

The tube spec/charts also show they all can be run as plate modulated class 
C amplifiers with 600 volts on the plate, 250 volt grid voltage on grid 2, 
and -150 volt negative voltage on grid number 1.  Yes, the 6146B shows the 
glass envelope can run at a higher temperature then the others and the plate 
current can be increased from 125 ma to 250 ma. when using the 6146B or W. 
The number 2 grid still has a max of 2 watts and the grid current is the 
same for all.  That is 4 ma.

I have plugged in many 6146B tubes in my old boat anchor rigs which 
originally were supplied with 6146 or 6146A tubes.  I have never had a lick 
of a problem when ever I have done so.  Since my transmitters were designed 
for the 6146 power ratings,  I have never "pushed the rigs to give the max 
6146B power output by increasing the plate current.  I think that would be 
unwise.  (The exception to this is my Collins S-line equipment which were 
built for 6146B tubes or at least came out of Collins with the B tubes 
already installed.

That said, to be honest,  I think the talk about B tubes not working in A 
tube transmitters is a bunch of BS or falsehood as I have never experienced 
the horror story myths I have read about B tubes from time to time.  I base 
this upon the spec sheets and the fact I have never had a problem 
substituting an A tube with a B tube.  As I mentioned earlier, I have never 
"pushed" the rig beyond the A tube ratings after installing a B set of 

I am well aware of the WARNING given about using a B tube in place of A 
tubes by one individual.  (I am not trying to slam him but I do disagree 
strongly with his paper.  I don't know anything about using these tubes in 
VHF applications but only in HF applications).  All I can say is, the spec 
sheets point out you can replace an A tube with a B or W tube and I have 
never had a problem doing this.  I've done it enough times without a problem 
and based on the spec sheets, they indicate no reason for having a problem. 
Another good ham friend of mine has used the B or W tubes enough times too 
and he too has never had a problem with the substitution.

Today, in 2011, new 6146B and 6146W tubes are sure a lot easier to find then 
6146 or 6146A tubes.  I've also been able to buy  NOS military 6146W tubes 
for less money then NOS 6146 or 6146A tubes.  I can buy new W tubes for 
about the same or less money then used 6146 or 6146A tubes.

I am writing this so others who may have a fear of using a B or W 6146 in 
place of a 6146 or 6146A tube should try it and find out for yourself what 
is fact and what is fiction.

Am I alone with never having a 6146B substitution problem?  I'd sure like to 
hear from others who have done the switch.  Have you personally ever had a 
problem doing this?  The spec sheets say you should have no problem and I 
have had none myself.

Lee, w0vt 

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