Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Hallicrafters SX-62 - low volume
#16

This is coming along. Found a misplaced wire and a capacitor. Still need to go through and finish cleaning this up, but I think it’s much better. A new side cutting pair of snips has helped. I’ve put in two Sprague electrolytic caps. Very nice solid units if expensive. 
Just waiting for my NOS 5U4GB tubes to arrive. 
I think it will be ready this weekend to bring up with just the rectifier tube and see how it goes. It is unclear to me how much current it should be pulling with just a rectifier in place.


Attached Files Image(s)
               
#17

Quote:I think it will be ready this weekend to bring up with just the rectifier tube and see how it goes.
The B+ can soar without a load, possibly taking out the filter caps...

Set OFF, measure the DC resistance of B+ to B- at the power supply. That resistance will dictate the load current based on the highest published voltage in the schematic, usually at the screen of the output tube, if no rating the plate voltage figure would apply also. If the calculation exceeds 80ma recheck measurements and calcs. If consistent, check all B+ paths for miss-connections or shorts...

A resistance of from 15k and higher is good...

Any resistor/inductor in the main B+ line or B- can be used as a shunt to determine real-time current. Measure the devices resistance and record. Place a voltmeter across that device and power the set. the voltage measured calculates to the milliamps flowing in the B circuit...

Caution meter leads are live, avoid handling the meter...

The greatest consumption of B current is the output tube(s). Controlled by the grid voltage.

It is possible to alter the grid bias voltage as long as distortion is not introduced, doing so can save both tubes, output transformer and overall B current as well as a cooler operating receiver.

GL

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Shadow Meter Bulb
I think after all has been said, I will use the same bulb that is specified for the dial pilot light which is a #55. I ...georgetownjohn — 07:31 PM
12' Philco
There was also this Philco! klondike98 — 07:25 PM
HiFi (Chifi) tube amp build - but my own design.
I expected a challenge and this is just part of it. But, it's also supposed to be fun, entertaining, informative and enj...TV MAN — 07:12 PM
Shadow Meter Bulb
Butting in here with a question. Since the shadow meter is connected directly to the 1st and 2nd I.F.'s wouldn't the met...RossH — 06:43 PM
HiFi (Chifi) tube amp build - but my own design.
Mike, Tim; you are about to enter the twilight zone. Doo doo doo doo, doo doo doo doo This is something alright. I'm go...RodB — 06:26 PM
HiFi (Chifi) tube amp build - but my own design.
:lol: We need to start a singing radio group! I play the guitar, so maybe get a few vocals? Anyways, Mike, I did try mou...TV MAN — 05:56 PM
HiFi (Chifi) tube amp build - but my own design.
And so does a barber shop quartet. mmmmmmRodB — 03:54 PM
Shadow Meter Bulb
I did try an LED bulb in place of the original but wasn't impressed with the amount of light on the dial. Seems like it ...RodB — 03:51 PM
HiFi (Chifi) tube amp build - but my own design.
Tim Would mounting he transformer vertically change the hum, if used without additional parts? Also, in these amps...morzh — 02:25 PM
Shadow Meter Bulb
Gary I doubt it would introduce any noise. We use similar lamps for the panel indication, 12V AC lamps: they are LEDs...morzh — 02:15 PM

[-]
Who's Online
There are currently no members online.

>