Parts-box (Tek 465) Transformer - How to figure out ratings?
I'd like to build a battery eliminator to run an old Radiola 16 battery set
I just picked up. There are a couple of commercial battery eliminators out there (e.g. ARBE-III, and a kit from AES) that look real nice, but I'd prefer to build it myself with stuff from my parts box (i.e. free). In my parts box I found a Tek 465 transformer which (with its multiple primaries and secondaries) I figure I can use as the basis for providing the necessary voltages. (For those not familiar with circa 1926 battery radios, this thing appears to need six different voltages - I'm still trying to figure out the specifics here but looks like I need: A: 6V @ 2A B: 135V, 67.5V, 45V @ 60mA C: -9V @ 20mA A, B, and C all need to be electically isolated from each other) Figuring out the various secondary voltages is easy. My problem is that I haven't been able to locate any AMPERAGE specs on this transformer (Tek P/N is 120-0798-01). Anyone have specs on this thing? If not, anyone have any suggestions re how I might be able to roughly determine the secondary amperage ratings without letting out any magic smoke? Thanks - -Pete |
Parts-box (Tek 465) Transformer - How to figure out ratings?
In article ,
says... | | Anyone have specs on this thing? If not, anyone have any suggestions re how | I might be able to roughly determine the secondary amperage ratings without | letting out any magic smoke? | Gradually increase the load on one of the secondaries, whilst measuring the voltage and current. When the voltage decreases by about 5% below the open circuit voltage, note the level of current flowing. That will be the approximate current it is able to deliver. Anyone care to comment on the 5% rule of thumb? -- Regards, Harry (M1BYT)... Remove the 'NOSPAM' in my email address to reply. Free Amateur Radio Courses:- http://www.ukradioamateur.org |
Parts-box (Tek 465) Transformer - How to figure out ratings?
030929 0727 - Harry Bloomfield wrote:
In article , says... | | Anyone have specs on this thing? If not, anyone have any suggestions re how | I might be able to roughly determine the secondary amperage ratings without | letting out any magic smoke? | Gradually increase the load on one of the secondaries, whilst measuring the voltage and current. When the voltage decreases by about 5% below the open circuit voltage, note the level of current flowing. That will be the approximate current it is able to deliver. Anyone care to comment on the 5% rule of thumb? Also, check the heat generated onto the frame. If you cannot hold your fingers on the frame because it is too hot, then reduce the load a little until it is just warm to the touch. A transformer is designed to take a little heat. |
Parts-box (Tek 465) Transformer - How to figure out ratings?
030929 0727 - Harry Bloomfield wrote:
In article , says... | | Anyone have specs on this thing? If not, anyone have any suggestions re how | I might be able to roughly determine the secondary amperage ratings without | letting out any magic smoke? | Gradually increase the load on one of the secondaries, whilst measuring the voltage and current. When the voltage decreases by about 5% below the open circuit voltage, note the level of current flowing. That will be the approximate current it is able to deliver. Anyone care to comment on the 5% rule of thumb? Also, check the heat generated onto the frame. If you cannot hold your fingers on the frame because it is too hot, then reduce the load a little until it is just warm to the touch. A transformer is designed to take a little heat. |
Parts-box (Tek 465) Transformer - Results
Thanks to Harry and Indago for the replies -
I measured the transformer secondaries this evening using a big old Ohmite rheostat as a load (along with some parts-box resistors). I couldn't get exact readings on the higher voltage secondary due to excessive wattage load required, but the approximate values I was able to get are close enough for my needs. Before I get to the specs, I should mention that the transformer is set up with a voltage adjuster for high, normal, and low voltage ranges - I used the normal setting for my measurements. Vin was set to exactly 120 VAC with a variac. To figure out current capacity of each of the secondaries, I used the 5% Vdrop rule suggested by Harry. All values are approximate - your mileage may vary. Tektronix 465 Power Transformer Secondary Specs ==================================== Secondary #1 (Orange-White-Violet (center-tapped = White)) O-V: 128VAC @ 300mA (approximate) Secondary #2 (Yellow-Yellow) Y-Y: 20VAC @ 2.4 A Secondary #3 (Brown-Brown) Brn-Brn: 9.5VAC @ 1.4 A Secondary #4 (Blue-Blue) Bl-Bl: 12VAC @ 1.4 A Note that this transformer has a second set of primary connections - I believe these are used with the inverter option (8?). I didn't bother with these. Turns out this transformer is close enough to suit my needs. I hope to have my power supply done in a week or two - now waiting on a shipment of 22V zeners - my parts box should supply everyting else I need. I hope this info is useful to others as well. -Pete "Pete Chrisbacher" wrote in message ... I'd like to build a battery eliminator to run an old Radiola 16 battery set I just picked up. There are a couple of commercial battery eliminators out there (e.g. ARBE-III, and a kit from AES) that look real nice, but I'd prefer to build it myself with stuff from my parts box (i.e. free). In my parts box I found a Tek 465 transformer which (with its multiple primaries and secondaries) I figure I can use as the basis for providing the necessary voltages. (For those not familiar with circa 1926 battery radios, this thing appears to need six different voltages - I'm still trying to figure out the specifics here but looks like I need: A: 6V @ 2A B: 135V, 67.5V, 45V @ 60mA C: -9V @ 20mA A, B, and C all need to be electically isolated from each other) Figuring out the various secondary voltages is easy. My problem is that I haven't been able to locate any AMPERAGE specs on this transformer (Tek P/N is 120-0798-01). Anyone have specs on this thing? If not, anyone have any suggestions re how I might be able to roughly determine the secondary amperage ratings without letting out any magic smoke? Thanks - -Pete |
Parts-box (Tek 465) Transformer - Results
Thanks to Harry and Indago for the replies -
I measured the transformer secondaries this evening using a big old Ohmite rheostat as a load (along with some parts-box resistors). I couldn't get exact readings on the higher voltage secondary due to excessive wattage load required, but the approximate values I was able to get are close enough for my needs. Before I get to the specs, I should mention that the transformer is set up with a voltage adjuster for high, normal, and low voltage ranges - I used the normal setting for my measurements. Vin was set to exactly 120 VAC with a variac. To figure out current capacity of each of the secondaries, I used the 5% Vdrop rule suggested by Harry. All values are approximate - your mileage may vary. Tektronix 465 Power Transformer Secondary Specs ==================================== Secondary #1 (Orange-White-Violet (center-tapped = White)) O-V: 128VAC @ 300mA (approximate) Secondary #2 (Yellow-Yellow) Y-Y: 20VAC @ 2.4 A Secondary #3 (Brown-Brown) Brn-Brn: 9.5VAC @ 1.4 A Secondary #4 (Blue-Blue) Bl-Bl: 12VAC @ 1.4 A Note that this transformer has a second set of primary connections - I believe these are used with the inverter option (8?). I didn't bother with these. Turns out this transformer is close enough to suit my needs. I hope to have my power supply done in a week or two - now waiting on a shipment of 22V zeners - my parts box should supply everyting else I need. I hope this info is useful to others as well. -Pete "Pete Chrisbacher" wrote in message ... I'd like to build a battery eliminator to run an old Radiola 16 battery set I just picked up. There are a couple of commercial battery eliminators out there (e.g. ARBE-III, and a kit from AES) that look real nice, but I'd prefer to build it myself with stuff from my parts box (i.e. free). In my parts box I found a Tek 465 transformer which (with its multiple primaries and secondaries) I figure I can use as the basis for providing the necessary voltages. (For those not familiar with circa 1926 battery radios, this thing appears to need six different voltages - I'm still trying to figure out the specifics here but looks like I need: A: 6V @ 2A B: 135V, 67.5V, 45V @ 60mA C: -9V @ 20mA A, B, and C all need to be electically isolated from each other) Figuring out the various secondary voltages is easy. My problem is that I haven't been able to locate any AMPERAGE specs on this transformer (Tek P/N is 120-0798-01). Anyone have specs on this thing? If not, anyone have any suggestions re how I might be able to roughly determine the secondary amperage ratings without letting out any magic smoke? Thanks - -Pete |
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