At sale are two good 572B tubes. I bought these in2005 from K5SVC who has been selling top-of-the-line transmitting tubes for years and still does here on . I bought them new from him as a spare set for my SB-201 linear. I put them in when received to check them out and they worked perfectly. I don’t remember if I ordered a matched pair but, knowing me, I probably did.I then took them out and put them on the shelf where they sat for all these years. According to the printing on the tubes they are Shuguangtubes made in China.A week or so ago I had my SB-201 out of the case checking to see if I could do anything about the cooling fan making a little more noise than I like. That’s still an ongoing project. However, I decided I will probably never need these tubes given the limited time I use my amplifier so I decided to sell them.I took advantage of the 201 being opened up so I put these tubes in and fired up the amplifier. It put out about 550 watts with these tubes (key down on CW) which was in line with what I get out of my trusty old Cetron tubes that I’ve been using in the amplifier.The tubes will be packed in the original bubble wrap and boxes I got them in and then packed againwith plenty of padding in another box for a safe journey to your doorstep by free Priority mail.Quickly mailed out from the United States.

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