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Most Power? You Can Swing Into A Typical Pillbox

Wire Weasel

Wire Weasel

Senior Moment
Dec 13, 2008
3,115
780
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Hey guys,

Take your typical low drive pillbox. Maybe lower figure for two pills, maybe higher for 4, 6 or 8 ??

These pillboxes accept a low dead key (1-4 watts) as example but also accept a an AM PEP on the swing that can be much higher. I'm seeking to know what the general limits are.

Example, a common radio seen driving pillboxes are the medium power exports. Like a General Lee. The Lees swing up into the 30-45 watts range.

So how much higher can you go on the swing without doing any harm to the pillbox?

I have a Galaxy DX 94HP. I can set the variable DK below 4 watts to any point, but it will swing up to 110 watts on the peak. Wondering WHICH pill boxes I could drive this thing with safely? Would it have to be a high drive box?

What is the safe max PEP imput level for a two pill low drive box? Might vary with type of pill too....

Has anyone made a list/chart/guideline of this kind of stuff?

Thanks!
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TNT350 - 2x2879, Class B bias, low/high power, switchable ssb delay, fan cooled. Max amp draw 48a, install recommended with 8ga wire and 50a fuse. Max input carrier of 5w or 150w max carrier from amp. Max peak input 120w.
Although it saids 150w carrier that might be a little high. But for ssb, 100 watt on ssb for the input would be a little easier on the amp.

At around 30w drive into this amp on ssb, normal out put is around 300. I have heard where some guys have seen this box do 400 on ssb with higher drive and not have problems.

Although it is just a "b", it still sounds fairly good. I've had one for about 5 yrs now and no problems.......
 
your 110 watt radio is way way too powerful for a 2 pill or a 4 pill box . youre worried about dammaging the box , but long befor that happens your signal will become crap from pushing the pills beyond their clean capability .

basically , you have a choice to make ....
you have to decide who knows more about the pills/transistors in your box . the people that invested the money and scientist to design and make them (toshiba in the case of 2879's) or the folks wanting you to buy a amp with minimal parts made in some part of their home with no bias for a modulated signal in the amp .

if you want to believe toshiba ....................
http://www.semicon.toshiba.co.jp/docs/datasheet/en/Transistor/2SC2879A_en_datasheet_071101.pdf
a 10 or 12 pill should be driven pretty cleanly .

if you want to believe a guy with a soldering in in front of his TV (or one that uses solder monkeys) then take your pick
 
TNT 600 (mobile) 4x2879, Class B bias, switchable ssb delay, fan cooled. Max amp draw 110a, install recommended with 4ga wire and 125a fuse. Max input carrier of 20w or 300w max carrier from amp. Max peak input 240w on ssb.
 
ROTFLMAO!...
Wire Weasel, you are looking for a 'BS' filter! Good luck.
Take your original specifications about power and convert all of them to the same type of measuring units, but not Pep. Unfortunately, that depends a lot on the amplifier's builder for supplying any figures in recognized, and accurate units (good luck).
Then take a look at what the transistor's builder/manufacturer says about their product.
Compare the two sets of figures while making allowances for the efficiency of any amplifier according to class. Also if there are any 'padding' circuits on the input of that amplifier, how far out of 'spec' each amplifying device is being operated, and the typical allowance for 'sales' BS.
What'cha got?

That's just a -slightly- nicer way of saying the same thing the 'Booty Monster' said. There is so much mis-information about 'CB' amplifiers, and that's why they are treated as a joke in almost every case. Some of that mis-information is unintentional, but some is definitely intentional! You get to decide which is which :).
Is there an easy way of doing that 'deciding'? Don't know about the 'easy' part, but there is definitely a good way, and that's to learn how all that 'stuff' works. You don't do that on forums, just too much of that 'mis-information' floating around.
Have fun.
- 'Doc

Oh, about that 'class' efficiency thingy. Don't use the most efficient figure for that (it's usually given in a percentage range), use the mid-range or low efficiency figure. You ain't never gonna see that max efficiency figure anyway in 'normal' use.
 
It's really difficult to answer that questions without more information about the amp (what 'Doc already said). The max drive without hurting something can also be (probably is) a lot different than the max drive that will guarantee a linear output signal, which is going to depend on the transistors in use. It also is going to depend a lot on the input swamping (if any) of the amp.
 
pretty much anything past a 12 to 15 watt swing into a 2290 driver is already causing harmonics then the main amp section sees that and then amplifies that
 
555 said:
pretty much anything past a 12 to 15 watt swing into a 2290 driver is already causing harmonics then the main amp section sees that and then amplifies that
Click to expand...

The harmonics are there in a "pill" amp no matter what. Overdrive causes saturation which produces IMD. The only way to get rid of harmonics is with filtering. The proper amount of drive is what the recommended specs are, although that is hard for us to comprehend:D
 
Arnt most specs on transistors stated for a class ab ? Not trying to starty crap just wanting to know.
 
toshiba doesnt say anything about bias class or mode of operation affecting their 2879's output level . its a 100 watt PEP device with a 6 watt typical and 10 watt max drive level to reach its rated output , they dont give a minium level to reach that 100 watt pep level so some amps may need even less power for full power per 2879 . there is a difference in efficency of power (12 /110 volts)usage/drawn between class ab and c biased amp but toshiba gives no indication that will affect the power output capability of the transistor .
http://www.semicon.toshiba.co.jp/docs/datasheet/en/Transistor/2SC2879A_en_datasheet_071101.pdf

near the bottom of page 3 of the PDF for them they have two graphs . the first shows power input to output . looks like a little under 5 watts will push it to 100 watts , which matches pretty well with it being a 13 db gain device .

the second one shows intermodulated distortion to power output ratios . you see the graph is gaining distortion as the power output rises and it stops at the rated pep output . going beyond that point just increases IMD which leads to splatter/bleedover and can also cause harmonics that affect other electronics nearby .

heres some more info on bias class that discusses their efficencys also
Classes of Amplifier Operation
 

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