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

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

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

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.

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.

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

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