I was talking about the pass capacitor, using a big one seemed to interact with the choke and mod iron, a big cap had the sound muffled, or something, I was disappointed with the results. I tried changing the size of the cap, and found 4 uf I think sounded natural. I had tried all the way up to 40 UF.
The power supply has 70 uf or more in it... Now that I actually have a good mike and preamp, maybe I should try other values again. More farads in the power supply is always better, but you need step start or some way to bring it up gently. Some run the voltage on all the time and switch the cathode, I never tried that, easy with triodes likely, not sure about tetrodes.... WA3JVJ has a push pull parallel 805 mod deck with a huge string of computer type caps, gives a full farad or more, and he runs the voltage on all the time. I think its quite crazy, about 60 computer grade caps in series parallel, at 2000 volts or whatever, if one cap fails, the explosion and mess will likely be very nasty! Brett N2DTS > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of John Coleman, ARS > WA5BXO > Sent: Tuesday, November 25, 2003 9:25 AM > To: [email protected] > Subject: RE: [AMRadio] Re: Modulation transformer ID and repair > > > I guess the "more is better statement" is strictly a personal > preference. What I should have said is "If you want the > audio waveform > to not be modified by the output circuitry then more is > better". Having > to little capacitance will modify the audio wave form and can > shift the > phase of lower frequencies for instance if a 200 cps note and > a 400 cps > mote or together and appear as natural harmonic causing > certain peaks of > a non sinusoidal wave to go positive then the shifting of the phase > relationship between these two frequencies may cause a > repositioning of > the peaks and there by cause the loss of the peaks. This can sound > better. I guess for some, better sound is not always the > natural sound. > It can even shift it so that the peaks go negative. This is also done > with certain settings of tonal control circuitry. > > > 73,John, > WA5BXO
