Hi Jim, What do you mean exactly? Try using the different impedance taps on the UTC's? Sorry, but I think I might be on the verge of a nasty cold! Tom
--- On Wed, 3/23/11, Jim <[email protected]> wrote: From: Jim <[email protected]> Subject: Re: NEOTEK: Adding Transformers To: [email protected] Date: Wednesday, March 23, 2011, 12:10 PM Hi Tom, After you get the project built up and do some testing, if you have time mess around with the secondary terminations. I'd be very interested to find out what happens. Regards, Jim At 12:40 PM 3/23/2011, you wrote: >I received a couple UTC A20's and should have my Edcor's in tomorrow. I >should have the chassis made and wired by late weekend. I am very curious >to hear the differences and see if they are very noticable. Regardless, it >will be a fun project. > >Tom > >--- On Wed, 3/16/11, Brian Roth <[email protected]> wrote: > >From: Brian Roth <[email protected]> >Subject: Re: NEOTEK: Adding Transformers >To: [email protected] >Date: Wednesday, March 16, 2011, 10:11 PM > >On 3/16/2011 13:02, Ike Zimbel wrote: > > > > Hi Brian, > > I'm pretty sure you published those specs on the Ampex list...check the > > archive! > > All the best, > > Ike > > >Dear Ike, > >I forgot I had posted some measurements on the Ampex list! I found the >following from the Jan, 2005 archives, which I believe were measurements >of the "smaller" series of Edcors: > ><http://www.edcorusa.com/products/143-wsm600-600.aspx>http://www.edcorusa.com/products/143-wsm600-600.aspx > >Here is what I wrote 6 (!) years ago: > >The replacement Edcors (600:600 impedance versions) arrived today, and the >DCR was MUCH more reasonable. Approx. 54.1 Ohms primary, 54.5 >secondary. Level drop from open loading on secondary to 600 Ohms was just >a bit under 1.5 dB, much what I would expect. > >For testing, I breadboarded a "zero Ohm source" driver with a 5534 opamp >running as an inverter: 10K input and feedback R's, 22 pF compensation cap >(between pins 5 and 8) and 22 pF in parallel >with the feedback R to tame any overshoot and ringing from the opamp >itself. -3 dB response with the opamp circuit calcs to around 723 kHz. I >powered the 5534 with +/- 20 VDC from my bench >supply, which allowed just over approx + 24 dBu/m at clipping. > >1 and 10 kHz squarewave response through the iron looked very good, loaded >or unloaded, with just a tiny bit of overshoot and ringing. Frequency >response was beyond anything I could measure with my >Amber (bandlimited at around 500 kHz or so) which came up with -1 dB at >approx 6 Hz and 300 kHz. Bypassing the Amber and just watching the scope, >usuable response was extended, and limited by the >rolloff of the opamp driver on the top end. With a 50 Hz square wave, >there was very little tilt which indicates LF response well below 20 Hz. > >Next I measured THD, and at some of the lower levels I was fighting noise >picked up from the breadboarding! Here are various "spot measurements". > >1 kHz, 0 dBm = 0.0085% +10 dBm = 0.005% +20 dBm = 0.0025% (noise was >an obvious factor!) > >100 Hz, 0 dBm = 0.03% +10 dBm = 0.015% + 20 dBm = 0.05% ** > >50 Hz, 0 dBm = 0.055% +10 dBm = 0.035% +20 dBm = 0.18% ** > >20 Hz, 0 dBm = 0.07% +10 dBm = 0.085% + 20 dBm = 0.7% > >Spot checks at LF and + 20 dBm: 40 Hz = 0.3% 30 Hz = 0.45% > >(Actual 20 Hz numbers may be a bit lower since my 20+ year old Amber was >having a hard time nulling at 20 Hz). > >** Notice the THD dip at the "middle" levels at those frequencies. I >also think I detected a THD rise at levels below 0 dBm but was fighting >noise issues. > >I have a bunch of other numbers, but you get the drift. Looking at Jensen >choices, this Edcor is just a bit "rattier" than a JT-11-EMCF which sells >for $66.85. These Edcors are a bargain!! > >Bri > > > >------ > >View the list online at: ><http://www.mail-archive.com/[email protected]>http://www.mail-archive.com/[email protected] > >You can unsubscribe at anytime by sending an email to >mailto:[email protected] with "unsubscribe neotek" in the message >body. If you have any difficulties, or questions --please send an email to >mailto:[email protected]. > >The Neotek list is lovingly hosted by Catapult Web. Remember that any >message or reply sent to the list will be automatically forwarded to all >subscribers. > >Vive Le Neotek! > >Thanks. > ------ View the list online at: http://www.mail-archive.com/[email protected] You can unsubscribe at anytime by sending an email to mailto:[email protected] with "unsubscribe neotek" in the message body. If you have any difficulties, or questions --please send an email to mailto:[email protected]. The Neotek list is lovingly hosted by Catapult Web. Remember that any message or reply sent to the list will be automatically forwarded to all subscribers. Vive Le Neotek! Thanks.
