Vintage Philips QB 3.5/750 Tetrode Vacuum Tube

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    This Philips QB 3.5/750 Tetrode vacuum tube is designed for use as a High Frequency amplifier and oscillator. It has an output of around 750 watts!

    I received it as a gift some years ago and it's been sitting in a box in want of a new home. Since I'm not going to put it into service, I thought I would make up an acrylic display housing for it, so now it sits in my lounge room where I can enjoy it!

    This is a big tube - Really big! The tube is 145mm high x 87mm wide.

    Want to see what this tube looks like running? Check out this!
    This 1000w amp has two :)

    I found a data sheet on line with a sketch of the base, so was able to transpose this into CorelDRAW. I lasercut the box with enough clearance for the tube to 'float' in the middle. The Philips logo is engraved into the inside-surface of the sides.

    NEOMAMMUT, EvanFoss, LWyman, dmoisan, and 2 other people added this photo to their favorites.

    1. rahulb 37 months ago | reply

      What adhesive did you use on the acrylic? Or did you adjust the cut width to get a press-fit?

    2. Sascha Grant 37 months ago | reply

      Hi, I used IPS Weld-On 3 acrylic adhesive -

      It's very thin, I apply it to the join by touching the point of a paintbrush and allow it to 'wick' into the gap. It sets very quickly. I purchased this from the same place as I buy my acrylic sheet here in Australia.

      I have found that trying to press-fit acrylic can lead to it cracking :(

      If you are in the USA, it looks like Amazon stocks it :)

    3. 16 months ago | reply

      Il me reste 10 tubes QB 3.5/750 RTC dans leur emballage d'origine et neuves.

    4. Sascha Grant 16 months ago | reply

      Very cool :) I did have the original box with the padding which appeared to be coconut fiber but it was very badly damaged by rodents and not salvageable :(

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