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[Amps] 8874 tubes

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Subject: [Amps] 8874 tubes
From: Jeff Blaine via Amps <>
Reply-to: Jeff Blaine <>
Date: Thu, 26 Jun 2014 12:01:27 -0500
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I have a set of 4 pcs 8874 tubes for sale.  These are out of my Alpha 76pa 
3-hole tube amp.  
They still have plenty of output but they are far from spring chickens.  
Performance measured below so you can see what I’m seeing here on the bench.

If you are interested in these tubes, contact me offline (jeff @


The tubes are late 80’s vintage and may be the originals.  In the time I have 
had the amp, the amp was run at about 1KW out of respect for the amp’s age and 
the high cost of replacement tubes.  Shortly after I got the amp (3 years ago?) 
I put in grid protection circuitry and an additional fan.

Data from the 3 tubes now in the amp:

BAND    Ip                    B+            Po                Ig
80m        930 mA        2150V        1330w        40 mA    
20m        880 mA        2200V        1320w        53 mA
10m        920 mA        2150V        1160w        35 mA
10m        690  mA        2200V        900w        28 mA

Po measured with LP100A feeding a dummy load. 
Ip/B+/Ig read from 76pa meter 
Drive power was 80-90w for the first 3 runs; the last 10m (900w) where the 
drive power was 39w.

The 4th tube has similar good output but the amp would glitch from time to time 
with it.  I’m not sure this was a tube problem as there was a PS relay that had 
burnt contacts which I replaced about the same time.  
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