Author Archives: Administrator

I recently received an email from someone who built adapters to use 7F7 loctal tubes in place of 6SL7GT’s. He said that he didn’t like the sound of the 7F7 because the gain was too low. This was news to … Continue reading →

Anyone who has ever been out to Leeds knows I love bicycles. An acquaintance has been searching for a new bike and has been asking me for advice. On several occasions he has found something within his price range. But … Continue reading →

Some years ago I received a phone call: “Hello. My friend says you’re an expert on setting up moving coil phono cartridges. I have a problem: when playing piano records, during crescendos there is distortion on one channel only.” This … Continue reading →

I will never forget the first time I saw metal tubes; it was a pair of 6L6′s in a Bogen amplifier from the early 1950′s. Metal tubes were introduced by RCA in a Technical Bulletin in 1935. The first metals … Continue reading →

Someone ordered an Amphenol 86CP12 plug and backshell a week ago. Amphenol made a whole series of these to mate with tube & connector sockets. They were available as 4 pin, 5 pin, 6 pin, 7 pin, octal, 9 pin, … Continue reading →

This tube is more than 9″ (23 cm) tall. Maximum plate dissipation is 1000 watts. Max plate voltage rating is 30,000 volts. The 4PR1000B is pulse rated version of its cousin the 4-1000A. Filament takes about 21 amperes at 7.5 … Continue reading →

I am surprised that most builders of vacuum tube equipment don’t know about production tube sockets. Production sockets are designed for a very large number of insertions and extractions. The contacts are extremely rugged and can be replaced individually. The … Continue reading →

The 127A is the same as the 3-100D2 transmitting triode. Filament is 5 volts @ 10.5 amperes. Max plate ratings: 2000 volts, 210 ma, Pd = 100 watt. If you look closely you can see that the plate is similar … Continue reading →

This is a directly heated (10 volts @ 4.05 amperes) triode with 150 watt plate dissipation. Maximum plate volts is 2500 VDC and max Ib = 200 ma. You won’t see many of these around. Overall height from the pins … Continue reading →

I got into an interesting conversation via email with a customer about use of BNC connectors to carry high voltage. The HIPOT tester was already out so off I went. The Hi Pot tester used goes to 4000 volts RMS. … Continue reading →