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Jyd
| | Posted on Tuesday, February 19, 2002 - 8:37 pm: | 
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i was looking on this website and it was telling the dead key input on transisters,it says a sd1446 will handle up to a 7watt dead key. is that true? also it says that 2sc2312c are good for 30watts each.is that true? thanks |
Tech181
| | Posted on Wednesday, February 20, 2002 - 12:11 am: |
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Jyd,
The SD1446 may handle it but it's a bit too much. Key them with 3 watts. The 2SC2312 is a 18-20 watt final transistor, same as the 2SC1969's.
Steve
Tech181
Tech181@copperelectronics.com |
Warlock
| | Posted on Wednesday, February 20, 2002 - 9:05 pm: |
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In class AB a single 1446 should not have over .8w input (carrier), a pair 1.5-2, and a quad 3-4. |
Znut
| | Posted on Thursday, February 21, 2002 - 6:24 pm: |
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On some amps, say ones that are supposed to be high drive, like the boomer 250HD, what happens? Is some of the input "shunted" when the T/R relay is keyed? I would like to know how to make mine handle more input and still be nice to my pair of SD1446's, as well as my Dad's pair of '2879's.
Thanks,
Znut |
Bigbob
| | Posted on Thursday, February 21, 2002 - 8:46 pm: |
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Warlock:what frec.band u-talkin and what is the db-gain with .8w input......In page 61 of my 2000 RFPARTS cat. 14-30MHz sd1446 P out watts 90,P in watts 5,GPE(Min)dB@30MHz 13.; 27-50 MHz,LOW FM BAND SD1446 P out watts 70,P in watts 7,GPE(Min)dB@50MHz 10.All specs. Vcc=12.5or13.8 Volts. |
Warlock
| | Posted on Thursday, February 21, 2002 - 9:22 pm: |
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BigBob.
My reference is 27mhz. My statement is base on obtaining 100% modulated carrier. A single 1446 transistor in a biased "CB" style amp with app. .8w carrier in will yield app. 25w carrier output. With app. 18w forward or "peak" wattage the modulated wattage of that same scenario will be app. 100w peak or modulated power, thus resulting in 100% modulation.
These figures can vary, but are pretty close.
If you'd like to drive a single 1446 with a 5w carrier, by all means do so, I just haven't found that sounds all that great and runs hot as hell.
I'm no scientist, engineer, nor guru. Just practical observations passed along to help others sound good on the air and not damage their amps. |
Warlock
| | Posted on Thursday, February 21, 2002 - 9:26 pm: |
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Znut,
I would ignore most amps designated "HD". 9 times out of 10 it is bogus. The easiest way to know what to drive your amp with is the following:
If your amp is supposed to peak 250w, then you want it's carrier to be 25% of that or app. 65w. Adjust your radio or have it adjusted to wherever it needs to be to achieve that.
In really small amps like the KL60, your radio may have to be cut back to .5w carrier output so that the 60w peak amp has a 15w carrier. |
Znut
| | Posted on Thursday, February 21, 2002 - 10:06 pm: |
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OK, how can I make the amp take more input? |
Tech181
| | Posted on Thursday, February 21, 2002 - 10:30 pm: |
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Bigbob,
I like to run my amps at 1/3 of there PEP on the carrier. They sound good that way, don't splatter, and run cool as well. Of course I have my radios tuned to where they aren't doing much more over 20 watts PEP anyway. So I can run at a 1/3 without worrying about the surges from high outputs from "whatever tune" you may have.
25% output is a good rule of thumb also, especially if you are running a higher swinging rig behind the amp. With some dual final radios, running much more than 25% will heat the amp up and, over time may cause failure. Running a lower input level is better than overdriving.
Steve
Tech181
Tech181@copperelectronics.com
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Warlock
| | Posted on Friday, February 22, 2002 - 5:22 am: |
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Breaking it down scientifically.....beautiful!
For once I have someone that knows something backing me up! I feel so....so....accomplished....verified! (haha)
Thanks for the ego boost SS ;) |
jyd
| | Posted on Friday, February 22, 2002 - 2:15 pm: |
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yeah,but there ar other websites that say different |
jyd
| | Posted on Friday, February 22, 2002 - 3:49 pm: |
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i seen a site that said,a sd1446 is tested at 75% which is a 3watt dead key. it makes 70watts at 3watt key and is capable of a 7watt drive |
ss8541
| | Posted on Friday, February 22, 2002 - 6:20 pm: |
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jyd, check the link out i posted. those specs are from thomson (the manufacture) themselves. so those other sites may say something else. but if it doesn't agree with what the manufacture says, then...
also you are supporting mine and warlocks statements with yours. those transistors are tested at 75% of max output. so that means that the are capaple of 90w at max output (100%). but this is at 12.5v which is the test setup for that trans. at 13.8v it can do about 100wpep at 30mhz. anyway.. if you put a 3w carrier in and get a 70w carrier, then when you add mod, your only hitting 90-100wpep. that is a long way from the 280wpep (1:4 ratio; 70x4=280)that would put a 70w carrier at 100% mod.
so to be able to have the 1:4 ratio here, you need no more than about a 25w carrier (like warlock said). about 20w is best since these transistors are out of their linear curve past about 70wpep when used in a push-pull amp. when used single like in the stinger board it is about 50w. and .75w input will give you that 20-25w ouput carrier. now when you add your mod, you can hit the 90wpep max output to be at or close to 100% modulation. and since these trans are only linear up to about 75w each, then there needs to be some positive carrier shift (increased positive mod) or else you will still have some downward modulation (unless you keep the peak output under 70w for each trans used). the ppe (correct name for npc) will provide this offset, making the postive modulation match or even better go further than the neg peaks.
i'm not sticking up for warlock. but i have seen many of his posts on different forums pertaining to amps. he is usually right on (as he is here). i was here checking something else out, saw this and decided to post. |
Warlock
| | Posted on Friday, February 22, 2002 - 8:54 pm: |
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Some people say you can drive a prostock drag car back and forth to work, I suppose you could, but is it practical or the best bet for longevity?
Feel free to run a single 14 with 3w carrier, or 7w carrier. I don't recommend it.
After 17yrs of playing with amplifiers, I have learned much about what works and what doesn't. Just trying to help others. |
jyd
| | Posted on Saturday, February 23, 2002 - 9:16 am: |
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i put a 1watt carrier in my palomar 250 and a 45watt swing,which gives me a little over 260watts.and it stays cool to but now i have upgraded my radio so it will handle with eaz 14.5volts and stays cooler to,now putting 14.5volts to the radio and the amp gets me close to 300watts and both stay cool. |
Znut
| | Posted on Saturday, February 23, 2002 - 11:32 am: |
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On some amps, say ones that are supposed to be high drive, like the boomer 250HD, what happens? Is some of the input "shunted" when the T/R relay is keyed? I would like to know how to make mine handle more input and still be nice to my pair of SD1446's.
Thanks,
Znut |
ss8541
| | Posted on Saturday, February 23, 2002 - 2:56 pm: |
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since you said above that the 1446 can take 7w of drive each, it looks like you are overdriving them by about 31w (7x2=14; 45-14=31). this is also evident by the fact that you are -showing- 300w output from devices that can only put out about 225w max (and this is with a matched pair of high gain 1446's) in a push-pull circuit (2pill amp). when they are overdriven hard they put out a ton of harmonics that -show- as extra power on a wattmeter. the meter can't tell the difference between the power at 27mhz and the power being generated across the rest of the rf spectrum so it adds it all together giving you that big number.
and if you are testing it into an antenna this is even worse. the antenna is cut for 27mhz so all the other power is reflected back down the coax where it is added to the power again. so now you have an even higher reading than when measured into a dummyload. |
Jyd
| | Posted on Saturday, February 23, 2002 - 4:30 pm: |
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i am sorry,i did not make my self clear.7watt carrier is what the website said.i dont dare put a big carrier in mine 1watt key is what i put into it.i can get a 250watt swingon a rms meter.anyway it sounds clear and loud thats what i want.have a good day. |
Warlock
| | Posted on Saturday, February 23, 2002 - 7:25 pm: |
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1w swinging 45 into a Pal 250, I'm sure it does sound clear and loud....on all 40 channels at once. |
ss8541
| | Posted on Saturday, February 23, 2002 - 8:04 pm: |
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yeah i tracked what you meant. i was trying to find a subtle way of using the specs you gave to let you know that you were overdriving your amp. 7w is the max power (even in the form of "swing") that is supposed to be put into these trans. infact these trans will reach their max ouput of 100w before the 7w input level. that is why i used your 45w of "swing". power is power wether it is carrier or pep. for instance the vr9000 is capable of 45wpep on ssb when peaked. if you whistle into that radio in ssb mode into your amp, that is the same as putting a 45w carrier into that amp. a single tone on ssb (whistle here) causes a "carrier" type output on ssb. when you put 45wpep am into that amp that is still 45w, its just not continuos like a carrier.
so let me answer your 1st post on this topic simply and just leave your system out of the picture. the 7w is a -max- input regardless if it is carrier or pep. but if you do put in a 7w carrier it needs to be for fm or cw since an am carrier at 7w will leave the trans with no room for proper "swing". hope this helps better.
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znut, yes some is shunted to gnd through what is called a "swamping" network (resistors). but it isn't enough to make them true high drive amps. sometimes if you add too much swamping it can distort the input (and of course that shows in the output). if you want to keep your high carrier, you can get an attenuator pad from rfparts for $16-35 depending on level of attenuation needed. its easier to just lower the carrier of the radio. if you are close enough to someone that the amp needs to be turned off then they won't be able to tell the difference between a 1w carrier and a 4w carrier. |
Bigbob
| | Posted on Saturday, February 23, 2002 - 8:46 pm: |
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Well,I got 4 sd1446's in my boomer 400 and what you say(ss8541)must be true,my eagle 2000 has a 4.5 watt carrier,doesn't mod. on am anymore,anyhow with this carrier the boomer puts out 260 watts |
jyd
| | Posted on Sunday, February 24, 2002 - 9:27 am: |
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well for warlock,i live 1/2 mile from one of my freinds and he said i only bleed 2 or 3 channels.228541 307 told me that a 25 or 30watt swing was ok, so 45 is not that much mor.i just think it is time to close this subject.all i know is dead carrier is worse than swing.if i put a 15watt dead key then i would have some problems.but the whole issue is,when i put 45watt swing into it it stays cool.as for the carrier on ssb i always turn everything down,also i am not much of a sidebander. you boys have a good day. |
merlinn
| | Posted on Sunday, May 25, 2003 - 3:37 am: |
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Dear friends i have a RM KL60 AMP and the Mos TR is burned , my problem is that i dont know the
Mosfet reference because is scracht off.
Can anyone tell me please this reference.
Thank´s a lot. |
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