On Mon, Feb 24, 2025 at 05:28 AM, Robert Kembel wrote:
.........Note that the largest plate dissipation is about the same as the venerable 6146B at around 30 watts. The difference is that the 6146 is designed for continuous duty operation vs. low duty cycle operation. A number of hams have been bit by not being aware of power requirement when using modes that are in fact 100% duty cycle such as RTTY and (I think) FT-8.
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Bob,? K7DYB
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The comparison of horizontal sweep tubes vs the 6146 should probably include mentioning the fact that the vacuum tube manufacturers did not use CCS/ICAS ratings for nearly all the? sweeps (some exceptions)? because they weren't tested for those types of service. (that of course did not mean they wouldn't work!)
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The CCS? plate dissipation rating of an RCA 6146/6146A is? 20W.? (27W for a 6146B/8298A)?
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Collins, Heath, Hallicrafters (to name a few) designed their transmitters using the 6146 to put out about 100W (staying approx? within the ICAS ratings [25w ea] for a pair of them
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For comparison, the plate dissipation of a 6JB6 horizontal sweep tube (used in the Drake T-4X, TR-3[12JB6], TR-4, TR-6, TC-6) is 17.5W? (A whole 2.5W difference vs the 6146)
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Some had more dissipation.... The 6DQ5 for example in our beautiful HT-44's,? has 24W plate dissipation etc....
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That would make the 6DQ5 "better" than a 6146/6146A I would think.
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Now having said that,? the original 6146 had 20W CCS dissipation, what would the 6DQ5 have if it was rated CCS?
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I would submit that because horizontal sweep tube service actually is "CONTINUOUS"? (I.E, your TV was turned on in the morning and maybe not turned of until 18-24hrs later? (OR not turned off at all!!)? (wake up in the wee hrs of the morning to "snow" on the screen!!)
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That's about as continuous as it gets!.....so the 6DQ5 would have 4w more dissipation vs a "CCS" 6146/6146A
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Now, I will concede that Hallicrafters, Drake, Swan and all the others did indeed design and suggest operating sweeps at much higher peak power than would even be possible with? 6146s and included cautions to not "key-down" for too long...... But,? I don't think 6146's would fare any better than any sweep tube if abused at greatly higher power levels.
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Now to get back to the original (opinion) discussion, I really am with a few others here in that increasing the power output of an SR160 or an SR150? (even double [3dB])? is simply not worth the effort.
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Get a linear amplifier.
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By the way, I am looking for a REALLY nice SR-150 to put next to my Loudenboomer if someone wants to part with one! (It cannot look like it was stored in someones leaky-roof garage though)
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73/Rick
W7IMM
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Rick W7IMM