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Kattracker
| | Posted on Thursday, September 25, 2003 - 9:53 pm: | 
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I am still not seeing clearly the logic of a previous post and replies I made about the input wattage capability for a Texas Star DX-500.
Please understand I am not trying to argue, but I still dont see the logic in some of the replies to my previous post. It seems to me the Texas Star DX-500 should be able to handle higher inputs than some of the replies to my previous post suggested.
Here is the logic behind my thinking. 
The Texas Star DX-500 is supposedly the same as the 667, but without the driver pill, which is a 2SC2290.
The 500 and 667 both use four 2SC2879's and the 667 has a 2SC2290 driving the other four. The 500 is simply four 2SC2879's with no driver pill.
Therefore we have established the fact that both amps use the same pills, (four 2SC2879's) and the 667 uses one 2SC2290 to drive the four 2SC2879's
A 2SC2290 is good for about 80 watts at 4 watts drive. That would mean the 667 is getting up to 20 watts input for each 2SC2879 pill. Again, 80 watts (the 2SC2290) driving 4 pills. 80 watts divided by 4 pills equal 20 watts per pill.
If the 500 is really the same minus the driver pill, then it seems safe to say you could drive the 500 with up to 80 watts.
Now I don't mean dead-key, but it seems logical that you could swing up to that amount when considering the above theory.
If I am missing something I would appreciate anyones explanation who can accurately explain.
And once again, I am not trying to be argumentive but I am not seeing the light on this per my previous post/replies about the DX-500.
I appreciate all the people who took their time to answer my previous post.  And will appreciate anyone who takes the time to reply to this one. 
Kattracker |
Pig040
| | Posted on Friday, September 26, 2003 - 10:23 am: |
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Kattracker,
You are 100 percent correct. I used to have a straight 6 pill, and I used my tweaked and peaked 2970 as a driver. A lot of people low ball the input into these amps I dont know why. They can give you every technical excuse in the book but I know from practical knowledge you can do this. A friend of mine used a daves made 4 pill to hit a straight 8 pill, and it cranked!
Pig |
Kc0gxz
| | Posted on Friday, September 26, 2003 - 5:37 pm: |
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Kattracker
Actually I thought ss8541 explained it very well in a couple of his posts.
But, if you want "logic", drive your TS-500 with 85-100 watts. You'll see logic.
Jeff, kc0gxz. |
Bigbob
| | Posted on Friday, September 26, 2003 - 9:08 pm: |
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Kattracker,2879s are rated 7 watts in max,so the 667 must use a gain lowering circuit,sometimes called a pad either on the input of the driver or on the output of the driver to avoid smacking the finals with it's full output,7 watts are all thats needed for full output at their 15db gain figure,whether it be 7watts swing/peak or dead key,dead key will,admittedly,heat things up quite a bit more and leaves no room for swing watts.A dead carrier is just that,fully modulated you add 50% more energy or watts,since you are all ready at the limit of the input,trying to add another 50%just produces a very muffled audio,you can't put 10 lbs. of dirt in a 5lb. sack,many of these really smokin amps out there are padded because the makers know the the power junkies are gonna cram more and more watts into them and they almost always under rate them for drive requirements just for that reason.But the info you get from copper is right on,and believe the specs.or you'll poof your amp. |
Kc0gxz
| | Posted on Friday, September 26, 2003 - 10:44 pm: |
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ss8541.
You said and I quote, "Don't go with what you want to hear, but what is right".
Excellent line. You can't get much more logical than that. I have a few regulars around my area that will be hearing that line from me in the future. Consider it stolen, Rick.
73s and thank you.
Jeff. |
Fixit07026
| | Posted on Friday, September 26, 2003 - 10:54 pm: |
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Only the 667V " Variable" has the driver pill
And I think their is a DX 500 & a 500 V
you can drive the non variable box harder |
Kattracker
| | Posted on Saturday, September 27, 2003 - 9:35 am: |
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Here is a copy/paste of an e-mail I recently received from a MAJOR RF parts distributor. I forgot to include it in my original post.
"Sorry for the delay, I was out yesterday. I find the best driving power is about 4-5 watts max carrier, with 15 watts peak per transistor. This
should assure a clean signal with good modulation.
Best Regards"
The "per transistor" is what supports my theory to some degree.
I would apreciate any comments or explanations as I still have an open mind on this, but I have yet to see it any other way.
Kattracker |
s8541
| | Posted on Saturday, September 27, 2003 - 12:15 am: |
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jeff, i see that you quoted my post, but yet no matter how many times i have refreshed my browser, it does not show on my end. so i guess there is either a snag on my end or else my post wasn't politically correct enough for the copper moderators. i have had both happen to me in past(i have been away for a while) so i'll just wait and see.
NOTE!
SS8541,
If you could e-mail me your address to Tech808@copperelectronics.com I will explain why your post was not posted.
It might be just a mistake on your part but please look at the top of this post you have s8541 not SS8541.
As you have been away from the Forum for awhile you may not know that we have had problems with people useing another's Copper ID / Name to make post's.
I am used to seeing SS8541 and when I see the above s8541 with no e-mail address for you, I cannot check to make sure it is you posting.
Thanks,
Lon
Tech808
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Kc0gxz
| | Posted on Saturday, September 27, 2003 - 9:49 pm: |
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ss8541
Actually, your post WAS put up, but shortly after I made a return comment in regards to your post, it was removed. Otherwise, how could I have possibly quoted you.
But don't feel bad. It's nice to know that I'm not the only one here that is "politically incorrect". Not all of my posts make it either.
73s Rick.
Jeff. |
ss8541
| | Posted on Sunday, September 28, 2003 - 10:49 pm: |
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kc0gxz, that is what i was saying, either it had been up for a short time and then removed, or else it was just not showing on my end. i had made a post one time in the past, that did not show on my end 25min later, but there was a reply to my post, so i knew it had to be there or was there at one time. that next morning the post that i made was there, added after the 'reply' post. never have figured out what happened there. then i have had some that never showed up.
tech808, i know i was being a smart a$$, but i get like that sometimes when it seems like someone wants to believe what sounds good over what is true. so now that i know that it WAS rejected, i know why you did't let it ride. i don't need it confirmed in an email. and i have no hard feelings about it. that is your job, and your call.
i am not going to add anything else to this post technically because he has had 3 answers from 3 professional techs in antoher post on this subject. all the answers we gave were very close to each other. funny that our answers were all so close if they aren't/weren't right. he says in his last post above that he has yet to see it any other way; even after our answers(one answer was actually an answer from texas star themselves via kc0gxz). sounds like he had his mind made up before he even asked the question. |
Kattracker
| | Posted on Monday, September 29, 2003 - 7:36 am: |
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ss8541,
No, my mind was not made up before I ask the question. I temporarily was leaning towards the answers and theories I got elswhere until I heard covincing answers here.
I have yet to hear anything here in as much detail as I got elsewhere. Some replies here definetly don't agree with my thinking and that is fine, but no one actually explains it in detail. I get many answers here that simply disagree with no concrete theory to back it up.
If you have the answer I would like to hear it. Please re-read my previous post on why I beleive as I do so to be sure we are on the same page. After you read it I would welcome your reply.
Kattracker |
Bigbob
| | Posted on Tuesday, September 30, 2003 - 12:22 am: |
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I don't think the variable pot can withstand sustained high inputs,thus high-drive is not recommended,besides if you got the bucks BUY one and experiment I don't have alot of money,but have done this with a shooting star 225 and it still runs clean and tight like new,sooooo. |
Bigbob
| | Posted on Tuesday, September 30, 2003 - 12:25 am: |
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I would get one myself but I need at least 3db over 400,so my next amp is going to be at the very least 1500. |
Kc0gxz
| | Posted on Tuesday, September 30, 2003 - 12:58 am: |
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Kattracker
First of all, lets get something straight. I am not an amplifier expert by any stretch of the imagination. But I have been in enought of them over the years to know my way around them and I am also aware of their differences.
Since you insist on seeking answers from us non-experts, I think you should go to the "Ask The Tech" section of this forum and ask Tech307 the amplifier questions that you have. I believe he's probably the sharpest amp man on the forum. He knows these TS amplifiers.
Now that that's out of the way, try this. Order a schematic from Texas Star for the TS-500 and one for the TS-500V. Once you have them, you will see that the main board layout are almost identical. But if you compare the RF input network, you will see a difference.
A lot of people think that the Texas Stars are all pretty much the same. For example...Take the TS 400 and the 500. 4 X 2290s in the 400 and 4 X 2879s in the 500. According to specs, there is a power difference of 100 watts on SSB. (BTW. Not nearly enough difference to justify an upgrade from a 400 to a 500).
Now, TS didn't just take the 400 board and simply drop in some hotter devices. Other componets have been changed also. Especially at the input.
What I'm trying to says here is that these amps have differences between models and also differences within the same models. As in the 500-500V.
There is a reason why Texas Star says that this amp can safely handle this much input and that amp can handle that much input.
I know I didn't give you the answer you are looking for and that's why I suggested that you call Texas Star themselves and ask them. And as long as you have them on the horn, ask for the schematics. I can't help you any more than that. Perhaps Tech307 can.
Good luck in your quest for Amplifier-Logic.
Jeff, kc0gxz. |
Kattracker
| | Posted on Tuesday, September 30, 2003 - 7:45 pm: |
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ss8541, kc0gxz and bigbob,
Thanks for the reply. I appreciate the tips and info sources.
ss8541, I would gladly e-mail the info to you or better yet, give me your number and I will call you. My e-mail address is in my profile.
I would post it but it would take a lot of time to assemble all the information, compose all the info from many people and put it in a reader friendly make sense format. 
I would glady e-mail you , talk to you personally or forward all the info I have obtained.
One person I did speak with today was a guy from D*** M*** amps. He said his 400 (non driven) model uses 4 2879's and they (all 4) handle 70-80 watts input no problem.
His M400 (driven model) which is driven by a 2290 driving 4 2879's, hits the 2879's with 80 watts.
He says they have built numerous amps this way without any problem.
If you want any detailed info please let me know how you want it. Phone, e-mail etc.
Thanks,
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Tech808
| | Posted on Tuesday, September 30, 2003 - 8:06 pm: |
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Just a thought
Might I make a Suggestion?
Include your e-mail address in your profile and you can discuss this topic directly if you choose to, or move this topic to the Ask The Tech Section under Amplifiers.
As many of the post's are becoming repetative.
This way it leaves more space in the OPEN Section.
Thank you everyone, in advance for your cooperation.
Lon
Tech808 |
Kattracker
| | Posted on Tuesday, September 30, 2003 - 9:53 pm: |
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Lon,
Good idea and I agree with you.
I am willing to discuss this futher but another avenue has to be used. The forum is not practical for lenghtly discussions like this and also take up much space.
If anyone has any further comments please use my e-mail address. It is in my profile.
Kattracker |
Znut
| | Posted on Saturday, October 04, 2003 - 6:24 pm: |
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I recently tried driving 2 2879's, varying the input from 1/2 watts to 50 watts swing, average, not peak reading.
The most I got out was about 250. I was getting the best sound and "swing" with 4 watts swinging 20. The amp would push 200 to 220 like this. More dead key and it sounded worse and worse. |
Bigbob
| | Posted on Saturday, October 04, 2003 - 11:33 pm: |
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Znut you have to be sure the modulator in the radio is capable of fully modulating the increased carrier,you can be sure of this by viewing a scope printout of the modulated wave form,amazing what you can do with a computer and the right hardware and programs. |
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