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Poor poor little National HRO Senior L76
#39

Order came in today from Radiodazes. Some needed caps, rubber feet,and power cord. All of the pre war HRO's use a separate power supply. The earliest ones came with 2.5vac tubes. The reason I mention this is that the 2.5v tubes haul down A Lot of current. Set has nine tubes which equals about 11 amps of heater current. Meaning that the power cord has to be rather robust to handle the current. The OEM National power supply used a power transformer that has a 3vac winding to compensate for the voltage drop though the 4' cord.

The problem is it is difficult to find these days a cloth covered cable four conductor with two 20ga wire and two conductors that are 14  or 12ga to minimize the volt drop. After consulting with Henry over at Radio Boulevard
(Wonderful site for early SW radios) He's used 8 conductor cloth cover battery radio cable by tying 3 of the conductors together for each leg of the heater leads. Great idea.    

L-76 needs the cord replaced and 7C has the original one in fair shape. Both also need 4 pin plugs. So have to scare up a couple of Amphenol  shells and plugs.

Both set have 6V tubes which use about 3amps. Got the front panel back on L76 and power it up. Audio is working but not sure what else yet.

Terry N3GTE                                     


Messages In This Thread
RE: Poor poor little National HRO Senior L76 - by Radioroslyn - 06-01-2015, 07:33 PM
OT RCA 6T71 1950 TV - by Radioroslyn - 06-13-2015, 09:19 PM



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