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Anonymous
| | Posted on Sunday, July 01, 2001 - 12:12 am: | 
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An interesting read about how they perform a Turbo Tune that I found on another forum......
An actual dissection of an EE_ TT radio, by a HIGHLY qualified tech (Not me or anyone that I have ever met): (Quote)
Here is the actual t-tune on a dx2517 (6900) board.
replace q55(2sa473 stock) with a 2sa1012. npc mod, and crank amc wide open. raise power supply to 14.4v. here is you t-tune.
nothing is actually done to reduce voltage drop. the 6900 is a heftier board than the 3600, so maybe this is the reason that there is no reinforcing.
the npc mod is here to support their claim of "rebiasing of am modulation amps". not in this excerpt but from another. npc mod does exactly that. and the npc mod does work. but there is a problem. after the npc mod the modulation must be set to the carrier power that will be used at ALL times. also must be set with oscope. when it is set correctly, you'll have approximately %+/-125 postive mod with %100 neg modulation. if the carrier power is changed after initial set up,this will all change. you'll either have decent pos mod and poor neg mod (way less than %100) or very high postitive mod, and the neg mod flatlining. so the npc mod with a variable power radio is useless. also in this particular setup the amc pot was cranked wide open. basically the amc control was diabled. npc mod was totally uneffective at any carrier level due to this. and the modulation waveform looked like a square wave from any carrier power (1-12w here). and finally the biasing on the driver and finals were off. not a big problem for am but is for the linearity of ssb (alc was also wideopen).
b4 "correction process" radio showed 50w a.m. "swing" on pdc700 (from any carrier). afterwards showed 32w on pdc(43w true peak on oscope) from a 10w carrier. also had 43w pep on ssb. (both were adjusted to right b4 the point that peaks begin to flattop). dc voltage was also lowered to a "safer" 14.1v.
In their defense i must say that the meters were all calibrated, and that the rx looked as though it had been peaked. specs call for a 10db sinad at .5uv. i got 12db with a .5uv signal and couldn't "peak" the rx anymore. i could get the "audio" including noise to rise, but not the actual sensitivity. xtals were on freq, although "their" view of a straight up clarifier is different from mine.
I could tell by the waveform. when you have a radio showing 47w with flattopping on a scope and it says 50+w on a meter that should only be showing about 36w (at a true peak 47w output) with am mod, then you know that the other 14w (50-36)is distortion and harmonics. also the fact 1 of the coils in the harmonic filter had been spread was a giveaway that there were harmonics and other trash being generated. (End Quote)
So, what we have learned from the above is that:
A Turbo Tune = Dirty / Distorted Harmonic Filled Output + Reduced Reliability + A Voided Warranty through Ranger. (and all this for just an additional $65.00)
307 PLEASE CHIME IN ON THIS ONE!!! |
307 (307)
| | Posted on Sunday, July 01, 2001 - 7:34 am: |
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VERY GOOD...I posted the same "result" you did in this group a bit ago..There is so much BS coming to the groups about "Turbo-Tuned" radios , that I think what they do is try to "Confuse" people with jargon terminolgy. The truth is and it still applies that "Anyone" can peak a radio and it will sound better than a Turbo-Tune. I have test equipment out the ying-yang and hardly use it. I STILL only go for BEST SOUND that I can get and NOT the extra quarter of a watt. There are other things a "Tech" may do to a radio that may help out but I am talking about a quick peak here... |
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