Back To The Future, Toward The Past: EAGLE 515

[357]

Right, that is pin 3 (not pin 5) so it should have plus volts on it.

Read the voltage on pin 5 to see if you have any bias volts on your tubes, it will be in the 15 to 20 volt negative range (put your plus probe on ground and your black probe on pin 5).

.

21V on the drives, 0V on the finals, on stand by.
Should I be on operate?

 

[357]

FINALS

DRIVERS
Pin

1 0V
2 18V
3 37V
4 0V
5 -21V
6,7,8 N/C
9 -21V
10 0V
11 37V
12 0V

 

[357]

What about this socket?

Maybe there should be a tube here for filiment load?

:headbang

Heater Voltage ................................ 10.6 VHeater Current ................................ 0.45 A

That would be about right....

 

[357]

I'm almost positive this missing tube is the problem.

I can't believe that, I guess I need that tube.

And probably 2 20lf6 drivers now too.

:bdh:

I followed a yellow wire from the 40V tap to "B" and traced to pin 4 on the 10BQ5, then pin 5 is terminated to ground.
So this is why the drivers are 32V !!

So now I will wait for a 10BQ5 but the drivers took a beating.

FFS

 

[357]

That must be wrong

 

[357]

 

[357]

There must be a flaw in the driver circut.
I think the drivers are wired in parallel and they are supposed to be series.

Or that a 20V tap.

I need sleep, I'm stumped.

 

[357]

You fellas that have done the 515, do you put a resistor in 10BQ5 ?
There must be something that needs to be done.

 

[357]

What if I do this?

BEFORE

After

 

[357]

What if I do this?

BEFORE

After

OK I did this and the drivers are in series, only 16V though, they look alot dimmer.
Will it hurt to be dimmer?

Running out of ideas here.

 

[357]

I tested this and spread the coil to get twin peaks on the tune.
the tubes no longer flash up and the drivers are quite a bit dimmer.

Please chime in anytime to let me know if i did wrong,
thanks.

 

[Slam Dunk]

How's the amp running now? Four volts low is better than 12 volts too high. I think the drivers may have been toasted by the excess volts.

.

 

[357]

It was working but not very well.
Also the voltage was just too low and it would kill the tubes the same as being too high.
I think if I put in the 30KD6's like you mentioned, it will be much better.

 

[liquidh8]

How did you ever make out with this amp? I just got one today, cheap, and 2 sets of NOS unused tubes, one used set. There isn't a 10bq6 in it either, and a few things looks to be changed. Just trying to find someone who still has one.

Thank you

 

[kc8adu]

that was the crystal osc that was removed to make it an amplifier.
these were sold as cw transmitters to dodge laws against linear amps.was always meant to be a cb amp.you got the mod sheet in the mail a few days after the amp.
and the made in holland tubes all flash like that on cold start.they will be fine.
my fisher 400's 12ax7's all do that.
26lx6 are a sub for the 20lf6.not well known and can often be gotten cheap.