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Reviews Categories | Electron Tubes | Penta Labs 3CX800A7 Help

Reviews Summary for Penta Labs 3CX800A7
Reviews: 1 Average rating: 0.0/5 MSRP: $$400
Description: Replacement tube for the eimac 3CX800A7
Product is in production.
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K6AER Rating: 0/5 Jan 22, 2008 15:07 Send this review to a friend
Bad Quality Control  Time owned: 0 to 3 months
After testing several batches of their tubes, I will not use them for any tube replacements. This is the body of the letter I sent back with the last batch to their sales manager. Out of six tubes that have been sent to me only one tube passed as a usable tube.

Mike – K6AER

“Last month I received these three tubes and I guess they were a replacement for the failed tubes that I received several months before this shipment. Although I bought tubes from Eimac as replacements I decided to test these tubes to see if they were any better than the last batch.

I’ll cut to the chase. They failed miserably. In an Alpha amplifier with a test frequency of 14.2 MHz the tubes were tested using a two tone signal input.

• S/N 0706004 flashed over internally and repeatedly at 2500 VDC.
• S/N 0706015 required over 80 mA for 800 watts out.
• S/N 0706002 required over 80 mA for 800 watts out.
• In addition I noticed the pin length was different from pin to pin. Makes me wonder how close the internal construction is.

A healthy 3CX800A7 from Eimac will require about 30 mA of grid current for 800 watts out. Most tubes that I recommend for replacement are in better shape than the new tubes you sent me.

In testing the two batches of tubes you have sent me, has cost me many hours and at this time I wish no longer to have any thing to do with you products. I will not recommend Penta Labs as replacements for Eimac tubes.”

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