7 6F6 tubes. Sylvania Ken-Rad Raytheon Delco Amplitrex Tested

Before testing the heater was on for at least 2 minutes and plate voltage was applied for at least one minute. This allows for some thermal stabilization.

Also checked for noise, gas, shorts, heater to cathode leakage, and microphonics.

They were tested on a Amplitrex AT100. 

The Transconductance spec for a new tube is 2500 mhos. 

Amplitrex AT1000 results.

Tube Emissions % GM % mhos

Sylvania 104 100 2510

Sylvania 91 102 2560

Sylvania 114 108 2700

Ken-Rad JAN-CKR 91 94 2320

Ken-Rad 92 96 2400

Raytheon 103 99 2480

Delco 84 87 2180

Cleaning the tubes is being left to the buyer since often cleaning removes labeling.

Test results are written on the tubes.  These can be easily removed with a moist paper towel.

Domestic purchases can be combined to reduce shipping costs.

International shipping will be through eBay Global shipping Program.

Items usually ship the day after payment is received.