OT labeled 0.1 - 20KC +25 DBM - What mean +25 DBM ??

[kagliostro]

In the same unit where I recovered the pulse transformers (those of my other post), inside there are two very small chassis (near 15cm x 12cm) labeled as Amplifier, the tubes mounted are a 5654 and a 6aq5

On each chassis there is a small transformer labeled as follow:

TF - 1A - YY
Z 185+600:6000
(1-T-2):(3-4)
25 MA DC UNBAL
01,-20KC + 25DBM

(1-T-2) <50v
(3-4)      250v
S         <10v

what I understand is:

a 0.1 - 20Kc OT with an attitude to have max 25MA of DC current across it, the primary winding (6000ohm) is rated for max 250v - the secondary winding/s (185+600ohm) is/are rated max 50v

But I don't understand a pair of things

What mean the +25 DBM  that follows the frequency response of the OT ?

also

I can understand 25 MA DC but what means UNBAL ?

EDIT: does +25DBM menas that the transformer is rated for max 25mW of power ????

Many Thanks

K

p.s.: I can't post a photo of the transformer because it is labeled on the face that looks the other components

[sluckey]

dbm is a unit of power, just as Watt is a unit of power. In my world...

0dbm = 1mW = 0.001W
+10dbm = 10mW = 0.01W
+20dbm = 100mW = 0.1W
+30dbm = 1000mW = 1W

and +25dbm = 320mW = 0.32W

[kagliostro]

Many Thanks Steve

Franco

[HotBluePlates]

On each chassis there is a small transformer labeled as follow:

TF - 1A - YY
Z 185+600:6000
(1-T-2):(3-4)
25 MA DC UNBAL
01,-20KC + 25DBM

...

I can understand 25 MA DC but what means UNBAL ?

Did you read our other thread about using a push-pull transformer in a single-ended circuit? The big problem is a single-ended output tube placing unbalanced d.c. on the primary. Too much unbalanced d.c. reduces the amount of power the transformer can pass from the primary to secondary, may limit bandwidth and in the worst possible case, could permanently magnetize the core.

Your transformer is providing a allowable limit for unbalanced d.c.

[kagliostro]

Many Thanks HotBluePlates

now I've understand, the unbal = unbalanced refers to the fact that in an SE transformer the DC crossing the primary is'nt balanced by one opposite signal in the other half winding that in the primary of an SE transformer isn't present

Franco