The tubes are indeed different in several respects as are the amps.
The L4 uses 3-400 tubes with chimneys that curve in at the top toward the heat dissipating plate cap. The L4B uses 3-500Z tubes with chimneys that are straight (same as a Coleman lantern globe). Whether the tubes are interchangeable depends on the physical size (one of those tubes is smaller than the other) and there is, I believe, a slight difference in some of the ratings on the tubes. The info is available online. The L4 does not have a standby switch on the front panel. The L4B has a standby switch on the front panel. Not sure about the L4, but the L4B has adjustable ALC pot on the front panel. L4 uses two 100K 50 watt resistors in parallel for part of the the bleeders and ALC circuit in the power supply. The L4B uses two 50K 50 watt resistors in series for part of the bleeder and ALC circuit in the power supply. Those are the main differences to my limited knowledge. 73, Evan, K9SQG -----Original Message----- From: m coffey <r79b...@gmail.com> To: drakelist <drakelist@zerobeat.net> Sent: Thu, Jan 12, 2012 5:17 pm Subject: [Drakelist] L4 vs. L4B Can anyone tell me the difference between the L4 and L4B ? Can one replace the 4-400s with 3-500s? Mike _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
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