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Reviews For: Machlett 3-500Z

Category: Electron Tubes

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Review Summary For : Machlett 3-500Z
Reviews: 1MSRP: $195.00
Description:
The Machlett 3-500ZG is a high-mu power triode with a maximum plate dissipation rating of 500 watts. Cooling is by radiation and forced air through the base, along the envelope, and over the plate seal and radiator-type plate connector. It is intended for use as a zero-bias Class AB2 amplifier in radio-frequency or audio frequency applications. By eliminating the bias supply, zero grid bias operation greatly simplifies circuitry design. When operated in a cathode-driven circuit, a power gain of as much twenty times is achievable. Electrical Characteristics Filament Voltage = 5.0 Volts Current (Ef =5.0 V) = 14.6 Amperes Average Amplification Factor = 130 Direct Interelectrode Capacitances - Grounded Grid Input = 8.3 pF Output = 4.7 pF Feedback = 0.07 pF Maximum Frequency for Ratings = 110 MHz Mechanical Characteristics Base = 5 Pin Special Net Weight = 7.0 Ounces Maximum Overall Dimensions Length = 6.10 Inches Diameter = 3.44 Inches Mounting Position = Vertical, base up or down Cooling = Radiation and forced-air Recommended Socket = PSK410
Product is in production
More Info: http://machlett.com/
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0014
NB4R Rating: 2022-04-27
Mixed emotions and questions about the longevity of this tube. Time Owned: more than 12 months.
I purchased this tube in January 2017 to replace an Amperex 3-500 tube that developed a grid to ground short. It was in an Ameritron AL80B. The new Machlett tube was purchased from Machlett on Ebay. In October of 2017 I discovered the output of the amplifier would drift from 700 watts to 200 watts after tuning. I contacted the Machlett people via Ebay and explained the situation. They advised me to return the tube for testing which I did.
A few days later they contacted me and informed that the tube was defective. They sent me a replacement free of charge in warranty.

I have operated the replacement tube now for about
4 1/2 years without issue. I tune the amp for maximum output per the Ameritron procedures in the operating manual.

Machlett states on their website they have been in business over 100 years. They make many different types of manufacturing equipment including electron tubes. These tubes are manufactured in China. Time will tell how these tube will hold up over the long haul. They were easy to contact and pleasant to deal with. I wish them much success in the future.