quad of 100TH modulator deck.

Discussion in 'Amplitude Modulation' started by N2DTS, Aug 2, 2020.

ad: L-HROutlet
ad: l-rl
ad: abrind-2
ad: L-MFJ
ad: Subscribe
ad: Left-2
ad: Left-3
  1. N2DTS

    N2DTS Ham Member QRZ Page

    I am never going to use this again, so what to do with it?


    Its got variacs for bias and filament, meters for bias, filament voltage, plate voltage and current, and a nice LS56 transformer.
    800 watts of audio at 2500 volts, 900 at 3000.
    560 watts at 1500 volts.
    I have a bunch of 100TH tubes, maybe 8 of them, with 5 or 6 nice matching ones.
    Two separate decks, one just holds the tubes.
    No mod transformer.
    Do I part it out?
    WA3JVJ and AE7LP like this.
  2. WA3JVJ

    WA3JVJ Ham Member QRZ Page

    "Do I part it out?" I NEED A DRINK! ... quick some scotch! Those tubes should be worshiped! Just think of the glory! ...
  3. WZ5Q

    WZ5Q Ham Member QRZ Page

  4. N2DTS

    N2DTS Ham Member QRZ Page

    I suppose there is no market for this kind of stuff so I will part it out.
    Shipping 100TH tubes seems like a disaster waiting to happen though...
  5. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    100THs are getting scarce. Due to age, the tungsten filament structure is usually very brittle, so I would not risk shipping them. I'm sure you would find more than one BC-610 owner within easy travelling distance from where you live, who would be looking for spare or replacement modulator tubes. I have had numerous OTA contacts the past couple of years, asking if I knew of a source. I'd put them up for sale or trade for a reasonable price or exchange. I'm sure you will find takers.

    Based on cost and availability, there are better choices of tubes for building a new modulator from scratch, than a pair or quad of 100THs.
    K5UJ likes this.
  6. N2DTS

    N2DTS Ham Member QRZ Page


    The bias supply is 11,000 mf with two 250 ohm 25 watt resistors in series.
    I added a switch on the back to go zero bias, the tube deck can take 811a, or 572B tubes as well.
    WA3JVJ likes this.
  7. K5UJ

    K5UJ Ham Member QRZ Page

    Don's right; Lots of 610 ops around here always wanting spares. The 610 is a cool rig in many ways but the downer over the past 10 years or so is that the 250 and 100s are harder to find not to mention the 2A3s. Thank heavens Hallicrafters used 807s for RF. I wonder when they'll get scarce. The 2A3 situation sucks.
  8. K5UJ

    K5UJ Ham Member QRZ Page

    One suggestion is to trash the porcelain plate caps and get some spring grips. Apart from that, very nice.
    K4KYV likes this.
  9. N2DTS

    N2DTS Ham Member QRZ Page

    If I had them, but Don bought all the spring clips.
    Some of the metal plate caps with fins would be even better, get rid of the heat.

    What is the going price for 100TH's?


Share This Page