Sidebar Sidebar
  • You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
  • Click here to find out how to win free radios from Retevis!

16 pill

"go have a look at a real linear amplifier with 4X2SC2879's designed by some people who actually know how to build amplifiers and ask your self why their 4X2SC2879 box is only rated at 500-600W" (ALS-500M)

If a 2SC2879 is a 100 watt device - how is Ameritron coming up w/the extra 100-200W??? :confused:

Most of the tube data sheet(s) that I've read show the ratings for the device in class A, A/B1, A/B2, & C., when/if the tube is to be used in an RF circuit, the manufacturer's wattage rating is usually conservative, or have a low output (like when used in CCS applications). So why can't the specs for devices like a 2SC2879 be any different?

I guess what I'm asking is: what's the cut-off for the "correct" output for a transistor amplifier?? So far, all I've heard from Freecell is anybody & everybody who claims "X-wattage" output from "their" amplifier is "full of crap", & is only selling "junk".

Why does the Palomar 225 amplifier you're selling on your website run 2XSD1446 (70 watts each?) & not 2X2SC2879? Shouldn't it really be called a Palomar-140?

Isn't it possible to increase watts out w/ increased voltage? I'm sure there's a cutoff point, I just don't know where it is, & the more I read this thread, the more I'm confused.

An old timer once told me "If you can't dazzle them w/ brillance, you baffle them w/ bull$#it". If Ameritron is "The Amp builder who knows", maybe I'm asking the wrong guy?

I might not be an RF engineer, have a Amateur license, or have a PhD from M.I.T., but I DO fix nuclear reactors for a living, & know the difference between brilliance & bull$#it.

I'm NOT trying to start anything, & this is why I usually keep to myself. I'm just trying to learn something that I feel is important, as I've spent a little more than three grand on my mobile equipment & "thought" that I was doing it right.

Hope I didn't piss anyone off! If I did, oh well......
 
"If a 2SC2879 is a 100 watt device - how is Ameritron coming up w/the extra 100-200W???"

they know they can push the 2879 to 50% over the spec. if they can maintain linearity with the proper bias and suppress resulting third order IMD using low pass filtering.

"So why can't the specs for devices like a 2SC2879 be any different?
see the paragraph above.

"I guess what I'm asking is: what's the cut-off for the "correct" output for a transistor amplifier??

the cutoff output is the point where transistor gain drops off, linearity disappears and IMD exceeds -24db.. the drop in gain is quite evident in the 2879, at 5W in it produces 100W out but when you double the drive to 10W the resulting power output is only a little over 135W. drive input at this point is increasing much faster than the output, gain is reduced.

5Win/100Wout

dbgain = 10log(POut/Pin)
dbgain = 10log(100/5)
dbgain = 10log(20)
dbgain = 10(1.30)
dbgain = 13

10Win/135out

dbgain = 10log(POut/PIn)
dbgain = 10log(135/10)
dbgain = 10log(13.5)
dbgain = 10(1.13)
dbgain = 11.3

adding another 2W of drive (10+2=12) gets us another 5W of output. we've gone from 5in/100out to 12in/140 out and the gain of the transistor has been reduced by 3db..

"Why does the Palomar 225 amplifier you're selling on your website run 2XSD1446 (70 watts each?)"

because they're rated for 70W @ 50Mhz.. the 1446 (like any BJT) produces more usable power as the operating frequency is reduced or to put it another way, the gain of the transistor increases as the operating frequency is reduced. in addition, the Genuine Palomar 225 incorporates a 5-pole chebyshev low-pass filter in the collector output to maintain IMD products at well below (# is higher) the -24db. mil spec. @ 200WPEP output in class ab1 operation. in the case of the 1446 it is capable of producing just as much power as the 2879 rated for 100W out @ 28Mhz., particularly when devices from the higher end of the beta range are properly matched/selected and used. only designs engineered with absolute rf stability can make use of devices from the high end of the beta range.

see ST Micro Electronics Transistor Beta Coding Chart.
http://www.rfparts.com/transistors_info.html

"but the fact is a 16 transistor amplifier even biased will never draw 320 amps,...."

because you're measuring AVERAGE CURRENT. PEAK CURRENT is 1.414 times the AVERAGE MEASUREMENT, or 353.5A.. you can't SEE IT if the equipment CAN'T MEASURE IT but the PEAK CURRENT CAN BE DETERMINED IF AVG CURRENT IS KNOWN and if PEAK CURRENT IS KNOWN then AVG CURRENT can be determined by multiplying it by .707.
 
Last edited:
base

wouldn't the 16 draw less amps with less input drive? Also i find it hard to believe that any amp built by an amp builder is a pig even with proper upgrades. I mean the base is there it just lacks the filtering, band switching and proper biasing scheme. Many ham operators build simple amps that are full of harmonics. Maybe not 16 pill amps but they are experimenting and learning. It's everything else around the 2sc2879's that needs work.Especially in the CB world. I am not broadcasting I just like to talk skip.I learned some things. I would like to see a you tube video of someone running a 16 pill with the drive levels we have discussed and see what kind of Bird numbers come out. I kinda got pissed at you Freecell but when i actually checked out what you were saying I saw that you were right. Back to the Matrix!! nice one.
 
yes i caught that Linearone. I saw on your videos you running a 4000 watt pep 16 pill. What drive were you using. How many watts were you driving that amp with. Even tho you agree with Freecell you run the 16 just like everybody runs them. Full saturation and lots of harmonics watts. Everybody does it. Just like me.Lets see a video with 160 watts input into a 16 pill on the 250 amp power supply and see what the Bird says! If freecell is right we should see full rated output. I still don't know what i'm going to drive my 16 pill with. I may just get rid of it and get an Ameritron anyways that's what I really wanted anyway. I tried to trade the 16 awhile back for an HF rig and I may still do so. I traded the Magna Force 900 for a LDG 1000 tuner.
 
If I am not mistaken we were driving it with a 4x1446 amp. 3 pills work fine too. 5 pills show lots of watts. Usually the 1446 amp is around 80-160 watts dk, just depending on where he keys it etc. I will run it tonight and get drive levels both avg and pep.

buy a power supply, enjoy the 16 pill or get another tuner and ladder line and 300 watts and when the ameritron cooks it self (it will, ive re capped and put new devices in two of them) you can have all the hamster fun you want on 40 meters with the wire antenna your friends will swear is better than a beam.

everything has its place.

if ameritrons and palomar 225's were so clean and well made and produced so much more power on freq why havent guys been doing that for 20 years in the cb world? that 1600 fithy dirty cb watts will talk right over 800 clean hamster watts nomatter how you slice that turkey, no matter how many harmonicas youre playing.
 
blah

so lets get this straight you are saying 5 watts pep per pill being 80 watts pep fed into a 16 pill at 12.5 volts will yield 1600 watts? Because at 10 watts pep or 160 watts drive the 16 does 800 watts and swings forward. The spec sheet i read said 10pep watts per pill.
 
blah

So to get the rated watts [1600 watts]you would have to drive the 16 harder than 80 watts. Here we are talking about driving a 16 pill with 80 watts compared to the advertised 1x4 drive levels. It seems unreal. Even Ameritron rates their amp higher than the spec because they supposedly can control IMD and get away with it. I think that I will just not drive the piss out of my amp but i will drive it with more than 80 watts maybe about 200 watts sounds like a drastic change from the 500 watts I was using before. I think we have beat this thread to death and I don't think any 16 pill CB amp would be acceptable in Freecells eyes. I really haven't seen any ham amplifiers that use transistors. I know I havent heard of a 16 pill ham amplifier. Why not? Are tubes just more efficient or easier to work with?
 
"I don't think any 16 pill CB amp would be acceptable in Freecells eyes."

no one builds a Class AB 16X. the last one was built by TS.
only a Linear Amplifier can faithfully reproduce the original
(amplitude modulated) signal of an am/ssb transmitter.

AmPower, Davemade, Destroyer, Fatboy, Gator & XForce
are NOT Linear Amplifiers.
 

dxChat
Help Users
  • No one is chatting at the moment.


      Top Bottom
      Back