Re: {Collins} KWS-1 Ballast tube question.

The Amperite data sheet on the 3TF4 states that the normal lifespan of the ballast is 1,000 hours - less if turned on frequently.

73,  Colin  K7FM

On 11/13/2015 7:23 AM, Clark Turner wrote:
You and another fellow that answered, Colin, had told me the same thing. I had never noticed this tube Light up before. This morning I flipped the radio on and the ballast tube once again light up, mainly on one side, then as the 5749w came up the ballast tube current went down and the settled to a low dull glow.

The good news is that once again, the radio is FIXED. I have tons of Grid drive again and loaded it up on CW at 500 MA out with mid scale Grid Drive. Everything is back to normal. I was just being cautious as these tubes are now pricey.

Thank you to everyone that has responded! Its been 2 weeks of downtime, I cant wait to fire the rig up tonight after work and spend some time with the old girl!


On 11/13/2015 6:51 AM, Chuck Curran wrote:
Hi Clark:

I wan't sure how much the resistance element in the 3TF4 normally glowed, so I went over and turned on my KWS-1. First I took off the tube shield and then I flipped on the power.

What my rig did was the 3TF4 resistance element immediately started to glow in what was four different areas. Over a period of about 7-10 seconds each of these glowing areas became dimmer and dimmer, finally going dark as the 5749 filament became hotter and the current draw was reduced. So I believe your KWS-1 is performing in an identical manner to mine.

I would recommend leaving the power on and let all tubes warm up and then test for PTO output again.

Assuming you now have output, I would expect you to be interested in determining which tube is faulty, the 3TF4 or the 5749. You can test the 3TF4 with an ohm meter. Just check for continuity across pins 2 to 7, I found 9.7 ohms on one of my brand new spare 3TF4 tubes.

Good Luck with your KWS-1,

Chuck W9KR

On Thu, Nov 12, 2015 at 9:15 PM, Clark Turner <Clark@xxxxxxxxxxxxxxxxxxxxx <mailto:Clark@xxxxxxxxxxxxxxxxxxxxx>> wrote:

    My working and restored KWs-1 lost grid dive.  After my Friend and
    elmter came over with an RF volt meter to check stages and we
    discovered that the PTO was dead.  We found the Filament on the
    5749W tube was not lit up.

    We then found I could not test the ballast tube so I ordered
    another tube on Ebay. A brand new in the box tube and also a brand
    new 5749W tube.

    I installed the two tubes and this time left the tube shield off
    the Ballast tube to see if there as any shorts or arcing.

    The second I hit the power switch one side of the ballast tube
    lights up like a filament.

    Is this normal?

    My recollection is that the ballast tube never had any filament or
    glowing inside at all.

    I removed the 5749W tube and flipped the power switch and there is
    no Glowing of the Ballast tube at all.

    I installed a 6BA6 I had on hand and flipped the switch and
    instantly, the Ballast tube once again lit up on one side only.  I
    quickly flipped the switch off.

    Is this normal and should I leave the power on?  I am afraid to
    burn out another ballast tube. They are expensive and hard to find.

    If this is not normal, What is my next move?

    Thank you for your help

    480-695-2898 <tel:480-695-2898>

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