Post by Graham on Nov 19, 2019 21:16:43 GMT 12
I'm curious to know what the 3 items are that were discovered inside the steel cabinet that housed the Denon turntable I recently refurbished. The one photographed in front appears to some sort of double transformer with a Tamradio logo on the front. The other 2 appear to be some sort of capacitor but have no brand name but have labels SF1 and SF2, and as the control panel had control switches for a 'scratch filter' maybe they have something to do with that circuit. Any idea what they are 
  
|
Post by Owen Y on Nov 19, 2019 21:38:40 GMT 12
Hi Graham, TamRadio is Tamura Radio, a respected Japanese transformer company, especially radio/audio transformers. Same brand as used on a Sun Audio (Japanese) amp that I have here (pictured below). As to what those TXs are.... 
|
Post by Owen Y on Nov 19, 2019 22:23:56 GMT 12
They look like 1:1 'line' matching TXs. 600 ohms is a universal nominal pro/commercial 'line' impedance. There are 2 windings (as is usual with TXs), each winding is 'split in two equally ('centre-tapped'), which allows them to be linked (as is the case here with the visible external wire link). Ea winding is labelled 600 ohms, ie. 1:1 ratio, providing no gain & are low imped - ie 'line matching' and/or input/output isolation (ground) maybe. The split windings have the ability to be paralleled, so that 1:2 or 2:1 ratios can be configured. There is no 'current' specif (on the label at least, although there may be in the datasheet), which again suggests, 'balanced' or pro/commercial application. (All speculation on my part  )
|
Post by Owen Y on Nov 20, 2019 8:44:13 GMT 12
The SF1/SF2 look like TXs or coils too. Caps of that era were commonly paper-in-oil & were usually in weld-sealed box cans with insulated terminals. What is the other labelling on these?
|
Post by Graham on Nov 20, 2019 9:18:41 GMT 12
The SF1 and SF2 mystery boxes have no labels other than Denon Columbia on them.
They each have 4 terminals which appear to connect to 2 coils inside.
Resistance across one coil ( terminals 1-3 ) = 5ohms, and across the other coil ( terminals 2-4 ) = 0.5 ohms.
So my guess is they are some form of step up or step down transformer.
|
Post by Owen Y on Nov 20, 2019 9:58:05 GMT 12
Are terminals 1 or 3, unconnected to either 2 or 4? Usually, signal TXs would be fully encased/shielded.
|
Post by Graham on Nov 20, 2019 10:10:15 GMT 12
Yep, no continuity between the two internal coils. The case is heavy steel and totally encases the coils other than where the terminals are. Maybe they could work as MC step ups. 
|
Post by Owen Y on Nov 20, 2019 13:29:59 GMT 12
You could try... the high imped side should be your output, in order to achieve gain. However (i) ideally you want at least 1:100 imped ratio (ie. 1:10 gain ratio), (ii) there is usually lots more winding turns/core size in an audio TX in order to get adequate inductance/LF bandwidth, (iii) connect the the Gnd leg of ea winding together (iv) as said, the case should be fully enclosed, in mu-metal usually, for cartridge level signals.
|
Post by Graham on Nov 20, 2019 13:47:17 GMT 12
Ah. I was thinking the 0.5 ohm to 5 ohm equated to a 1 : 10 gain for an SUT.
It was just a passing thought for a use for them. I wonder what they were used for inside the cabinet??
|
Post by Owen Y on Nov 20, 2019 14:28:58 GMT 12
DC resistance also, is not the same as AC impedance
|
Post by colinf on Nov 20, 2019 20:20:41 GMT 12
Interesting, without measuring, like you say, they could be MC stepup transformers for a Denon cartridge. Was it from a radio studio? Perhaps the 600 ohm transformer coupled the left and right channels into mono for AM broadcast. But really need to measure them to be sure. Try searching on Google Translate for some Japanese pages for info.
AMR-iFi R&D
|
Pundit
Post by beeman on Nov 22, 2019 10:25:41 GMT 12
I have a bunch of similar transformers & would love to know what they are useful for?
|
Post by Owen Y on Nov 22, 2019 10:54:24 GMT 12
Line Matching, out from the turntable desk.
|
Pundit
Post by beeman on Dec 1, 2019 19:21:23 GMT 12
Thanks Owen, what function would these line matching transformers have - eg. What could I use them for?
|
)
