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Radio Road Which tuner to get and getting the most from it. Thank God, for the radio! |
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Radio Road Which tuner to get and getting the most from it. Thank God, for the radio! |
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In Reply to: Tube Rolling in MD 108 posted by JeremyB on July 20, 2005 at 01:45:09:
Per my experience, tube rolling is not common in tuners, but is a serious interest for me. I also find most do not have interest in tuner tube rolling.I modify tuners with better components for starters, align, then roll tubes. Quality components brings out the best in tubes and alignment is a plus. Contrary to many posts, alignment in older tuners does not drift so far out of spec as stated. However, re-alignment is best. I have had at least 10,000 NOS tubes to audition in the past. Playing with Fisher, Scott & EICO tube tuners, these are best performers in tuners:
6AU6
RCA grey plate late '50s to early '60s. Black plate square getter are also good quality, but not as consistant as the grey plate. Note: an RCA 6HS6 does give a good boost in sensitivity for first IF tube in place of a 6AU6, but many cascoded can have bad effects such as loss of adjacent signal rejection (wide passband due to too much gain) or can oscillate in the IF chain with too many 6HS6.6U8
Tung-Sol black plate or Telfunken. Note: I use these as sub for 6GH8 or 6EA8, but tube swapping in the RF or mixer may effect frequency readout a few mHz. If money is no object, Valvo E80CF is the best 6U8.12DW7/7247
RCA 12DW7 are great tubes. Philco label are RCA in every example I experienced. The RCA are better than Mullard too.EZ80
Older Mullard with shield are best. I tweaked tuner is quite sensitive to a quality tube rectifier.6AQ8
Telefunken are best performers every time. Mullard & US manufactures were not high quality per my experience.12AU7
1950s Brimar 12AU7 black plate square getter. Next is '50s CBS/Hytron 12AU7 or 5814. The absolute best in audio out circuits only is the Amperex E80CC/6085, but is taller & draws more filament current.12AX7
Varies with the circuit, audio circuits are most sensitive. I like Mullard 12AX7 the best. Nice airy & open sonics plus well balanced.6HS6
RCA is best. Scott label are RCA in my experience.6AL5
Mullard are best. Don't laugh as the 6AL5 are used as a high frequency detector tube in some tuners.6BL8
I prefer Sylvania.6EB8
Again, Sylvania.6EJ7
ITT label are good as well as more mainstream names.6KE8
Never sensitive in my circuits, any good brand name works well.Mainstream Tubes- I prefer Sylvania in RF sections, not IF or audio. I prefer RCA in IF or audio with exceptions listed above.
My 2 cents & have fun.
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Follow Ups
- Re: Tubes to 'look for'........ - Jimmy 07/22/0508:15:07 07/22/05 (1)
- Great info Jimmy. Thanks (nt) - JeremyB 09:15:49 07/22/05 (0)
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