On Sat, 20 Aug 2005 12:47:40 -0700, Frank Gilliland
wrote:

+On Sat, 20 Aug 2005 18:36:32 GMT, james wrote
+in :
+
+On Fri, 19 Aug 2005 19:51:36 -0700, Frank Gilliland
wrote:
+
++On Fri, 19 Aug 2005 23:08:10 GMT, the self-proclaimed "CB Amp God"
++Bill Eitner wrote in
.com:
++
++
++
++Jay in the Mojave wrote:
++ Hello All:
++
++ Yes this had to run in someone's mobile, I would think it took way over
++ 200 amps to run. This really has to be one for the hall of fame!
++
++ It would take nearly 20 amps just to
++ keep it on standby.
++
++
++Closer to 10 amps.
++
+******
+
+Closer to 15 amps. The filaments, with (6)6LR6s and (3) 6KV6As alone
+are over 10 amps. Then add in the switcing transisitors. If I remember
+correctly the original output tubes were 6LF6s. The amp is three tubes
+to drive 6.
+
+
+Closer to 10 amps -- it has a standy mode that reduces the current
+through the filaments and shuts off the inverter. Besides, I ran one
+across the bench a few years ago and measured the standby current.
+
+
++
++ .....A DC pig it
++ definitely is. However, as far as
++ output, by todays standards, it isn't
++ that big a deal. A daily-use 8-pill
++ is easily its equal.
++
++ I saved the photos on a disk. Where would you put this monster in a car
++ or truck?!??!!??!?! Hehehehhehehehe
++
++ On the floor, in the trunk, or in A
++ custom box in the bed. In those days
++ the radios didn't have the frequency
++ coverage that is common today. That
++ means that once it was tuned it could
++ be left alone.
++
++
++What a load of hogwash. This amp has a tuned pi-tank output that you
++can clearly see in the pics; i.e, you need to retune if you change
++freqs. Tube amps can be designed to be broadband just like solid-state
++amps, and solid-state amps can be built with tuned output tanks. But a
++broadband amp -- tube -or- transistor -- eliminates the tuned output
++tank, the result being harmonics that increase with non-linearity. The
++only difference between 'then' and 'now' is that ampheads these days
++don't give a rat's ass about harmonics bleeding all over the spectrum.
++
+
+Tuning was not as critical for that amp. When there was only 23
+channels, you set it at channel 12 and it pretty much was adequate for
+the whole 23 channels. You only had a span of 300 KHz. Granted it
+maynot have been optimum at the band edges, but was useable. For 40
+channel operation that maybe stretching it a bit.
+
+
+Quite a bit.
+
+
+I agree toaday most could care less about harmonics. The further the
+meter goes to the right the happier they are.
+
+
+Unfortunately, that's all too true.
+
+
++And as far as frequency coverage is concerned, the range of bipolars
++is generally narrower than power RF tubes, the latter being usable
++from 0 Hz all the way through to their maximum frequency. In fact,
++most are rated in their data sheets for use as audio amps. Even
++smaller RF tubes like the 6146 have been used in guitar amps. You
++can't do -that- with a 2SC2290.
++
+****
+
+Come on, crossover distortion at 12 volts is horrible compared to 450
+volts. For audio, Tubes of FETs are superior to bipolar transistors.
+
+
+Again, true story. Where did I say anything different? You need a
+feedback loop in order to reduce crossover distortion in a bipolar
+push-pull, but you can't put a feedback loop in an RF amp.
+
+
******

Well you can but it is difficult to keep the amp an amp and not an
oscillator. I was pointing out that Tubes and FETs are more usable for
audio applications than bipolar in my opinion.

++
++ And WHAT mobile antenna would hold a full KW, other than a 102 inch
++ stainless steel whip ?
++
++ A Firestick (heliwhip), the Francis
++ whips, or even a K-40 or an Avanti
++ Mobile Moonraker that was tuned right.
++ It has to be realized that when all was
++ well that unit was good for 600 dead-key
++ and 1200 peak.
++
++
++More like 300 dead-key (RMS/AM) and 1200 PEP (SSB). And to think that
++after all these years you -still- haven't learned the difference. Go
++crawl back under your rock, Bill.
++
++
+******
+
+Almost all of the sweep tubes ran in cathode driven more linearly
+wqith much less carrier output than most CBers like. Judging by using
+4 6LQ6s in cathode driven configuration with some bias on the contrrol
+grids,I saw between 80 and 120 watts as the maximum carrier pwoer for
+good linearity. For this amp more like 120 to 180 watts carrier. Sweep
+tubes are not the best fore AM amplification. They perform adequately
+for SSB. There you can realize more power out.
+
+
+Sweep tubes aren't very linear to begin with..... at least not when
+driven as hard as they are in these RF amps. The pi-tank is almost
+essential but does nothing to improve linearity. I've never heard one
+sweep-tube amp that didn't noticably distort the audio.
+

Correct on the PI-Network. It just filters and that is only minimal,
about 6 dB per octave IIRC. Besides I never stated that the output pi
network improves linearity, That is accomplished through drive and
bias for a set of given plate and screen voltages.

In low drive situation they are adequate. Back 30 yrs ago the tubes
were cheap. I knew soemone that got me tubes from a whosale
distributer for $3 a piece. I could get 811A's for $11 a peice.

For about 100 PEP output from a pair of 6LQ6s as compared to a pair of
6146Bs, I will take the 6146B every day.


+But my point was that PEP @ 100% mod = 4 x carrier, a fact which
+befuddles voodoo CB techs like Bill the self-proclaimed CB Amp God.
+

COrrect in that. A PEP level is 4 times that of the AM Carrier. That
is the power that should be used to determine maximum useful output in
my opinion.

+
+The again output power and life expectancy of sweep tubes are
+inversely proportional. The more out, the shorter the life span.
+
+
+That's pretty much true with all power devices.
+
+
+
+
+
+
+
+
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