811A 572B 3-500Z Vacuum Tubes For Sale

 

Please email us for orders by clicking on Order Now. See our Contact Us page. (please do not contact outside of email links)

We offer the highest quality 811A, 572B, and 3-500 tubes.

How We Test Tubes

All tubes are visually inspected and 100% tested in a high power, high voltage, dynamic tester. The tester measures peak emission, peak grid current, and voltage required to reach the saturated current. For example we test our 3-500Z’s for the peak emission that would allow over 1250 watts peak power output to a load. If a tube does not have that much peak emission, it has a filament reserve emission issue. Tubes are operated through several test cycles to be sure emission is stable and intermittent connections are not present.

The average testing time of about 10-15 minutes per tube is well worth the trouble. This is a much better form of matching and sorting tubes than just running them in a regular amplifier or worse not testing them and relying on the customer to operational test the tubes.

This testing method allows us to sort matched tubes at the high end of the power curve, where the tubes are working hardest and where sharing the load is most important. This is where matching really matters, when each tube shares the heavy load, not when the tubes are just loafing.

We do not use idle current matching (which is mostly useful in class A push-pull amplifiers).  We make sure tubes are matched when they are working hard.

 

For a filament voltage article please visit http://w8ji.com/filament_voltage_life.htm

Tube Failures

Some tube sellers will blame short tube life on filament voltage or grid current. We find most tube failures, other than outright gross thermal abuse to tube anodes, actually come from poor tube manufacturing and inadequate testing to weed out bad tubes.

The normal emission life of properly manufactured thoriated tungsten filament tubes is several thousand hours at rated voltage. By far the greatest shortening of life occurs with excessively cold filament operation, where the bulk of life can be lost. The most that might be lost through excess filament voltage might be a few thousand hours out of several thousand.

The normal age-in time is 200 operating hours. During that time it is important to be at rated voltage or above. Do not age in tubes at reduced filament voltage! As a matter of fact, it is not necessary to burn in any tube we sell.

Most tube failures on tubes will less than a few thousand hours operating time are either heat related (which is a dissipation vs time function) or manufacturing defects.

Command Technologies 3-500Z graphite anode for sale.

NOTE: There is no warm up or aging required. As long as you use our tubes within a few years of purchase, since we already run the tubes at more than normal voltage and power, no warm up or aging is necessary.

This tube is instant on. Just a few seconds and it is ready to go. We do recommend a cool down any time over 5-minutes at idle (no plate current) to prevent heat soak of the top seal.

Directly replaces Ameritron 3-500ZG 380-0500GT. Improved direct drop in for all 3-500Z amplifiers including older Drake, Heathkit, and Henry amplifiers.

The best 3-500 tube being manufactured!
One year warranty against manufacturing defects.

New Command Technologies 3-500 graphite anode tube, also called 3-500ZG and 3-500C for sale. It is a better-tested substitute for the Ameritron 380-0500GT and other 3-500 tubes.
There are currently just two plants, both owned by the Chinese,  manufacturing 3-500 tubes. Don’t let any company fool you into thinking there tubes are made elsewhere or by them.

I carefully selected the best and most reliable source for my tubes. All tubes are tested here for anode-to-grid breakdown voltage, anode-to-grid and filament leakage current, grid-to-filament voltage breakdown, along with peak grid current while running at peak emission limits with the filament at 5.0 volts. We actually do a real peak emission test and compare these tubes to a Amperex standard.

Matched pairs are selected for similar grid current curves at high power in a peak emission test. Other companies either match for idle current or they don’t really match at all. None of that truly matches a tube used in class AB2. We want parallel RF tubes to equally share load at high power. Users do not care about idle current. It isn’t push-pull AB1.

Because every tube is 100% tested there is no extra charge for matched pairs. We match tubes by the closest curve pair.

Warranty 1 year from date of sale against gas, shorts, and emission loss when operated within manufacturer’s specifications. Breakage or abuse failures are excluded. $300 each plus shipping. Order Now

 

New Command Technologies 811A Tubes for sale

NOTE: There is no warm up or aging required. As long as you use our tubes within a few years of purchase, since we already run the tubes at more than normal voltage and power, no warm up or aging is necessary.

This tube is instant on. Just a few seconds and it is ready to go. A cool down time is not required for this tube as long as the fan speed is adequate.

Fully tested dynamically (breakdown, emission, output power, and grid current) new 811A with 1 year emission and shorts warranty (user anode damage excluded). For a video see YouTube W8JI 811A History

 

Warranty 1 year from date of sale against gas, shorts, and emission loss when operated within manufacturer’s specifications. Breakage or abuse failures including melted or hot spotted anode are excluded from warranty. 811A $60.00 each plus shipping. Matched tubes no extra charge. Order Now

 

 

New Command Technologies 572B Tubes For Sale (due to the unreliability of all currently available 572B tubes we are temporarily withholding sales. We were told possibly November for good 572B tubes. Regardless of “brand name”, all new tubes come from the same few Chinese owned plants. Keep this in mind.)

NOTE: There is no warm up or aging required. As long as you use our tubes within a few years of purchase, since we already run the tubes at more than normal voltage and power, no warm up or aging is necessary.

This tube is instant on. Just a few seconds and it is ready to go. We do recommend a cool down any time over 5-minutes at idle (no plate current) to prevent heat soak of the top seal.

Fully tested dynamically (breakdown, emission, output power, and grid current) new 572B with 1 year emission and shorts electrical life warranty (user glass or anode damage excluded).

 

Warranty 1 year from date of sale against gas, shorts, and emission loss when operated within manufacturer’s specifications. Breakage or abuse failures are excluded. 572B $99.95 each plus shipping. Since these tubes are dynamically matched for grid current at a given output matched pairs, threes, or quads are no extra charge.  Order Now

 

 

 

 

 

Other Tubes and Tube Sockets

 

We stock new and used tubes and sockets of many popular and rare types, including EF Johnson sockets.

 

 

 

 

Tested used mil spec 4CX250R 7580W Tube, mostly Amperex. These tubes are fully tested. 30 day return if undamaged. TEMPORAIRLY OUT OF STOCK
$47 each shipped USA only. Order Now

 

Tested used YC156A tubes. These tubes are fully tested. 30 day return if undamaged and used in a properly designed amplifier.        $950 each shipped USA only. Order Now

 

Tested new or like new YC108 4CX5000 tubes. These tubes are fully tested. 30 day return if undamaged         $1450 each shipped USA only. Order Now

 

Tested new 3CX1200D7 tubes. Call for price on 3CX1200Z7 tubes. These tubes are new and fully tested but well beyond Eimac warranty. 90 day return if undamaged. 3CX1200D7 NOS         $980 each shipped USA only. Order Now

 

 

 

3-500Z style Ceramic EF Johnson $49

Hi-flow metal  3-500Z $79

8877 3CX1500A7 metal and ceramic  Eimac  $119

EF Johnson 3CX800A7 and similar Compactron style $29

Grid collets for various tubes, including 3CX800A7 grid collet

Also larger and smaller tube sockets, connectors, and chimneys.

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Contact for other special high and low power tubes and semiconductors. Thousands of tubes and semiconductors in stock!