I was looking over the chassis to my Zenith H511 and found that one of the IFs wasn't original. Also where a 12BA6 tube was supposed to be there is a 6BE6. Is this ok?

Nostalgiaair has the schematic and shows a 12BE6 as the converter and not the 6BE6 you have. Since the 6BE6 draws 0.3 amps, the other tubes are under stress with their 0.15 amp draw. The extra six volts doesn't matter, but the current difference does. Did you power it up? Where's the loop or (probably) the rod antenna?

It does have a 12BE6 on it but the socket I am referring to is supposed to have a 12BA6.

The loop is built into the back panel. I did plug it up but only for a few seconds. All I got was the bulb that lights up the Zenith logo came on dimly.

A classic example of a set that I would not bother to power up (and I do that a lot). When it has been assessed visually as being "hacked" & things are clearly wrong. It is really pointless and not worth the risk of damage, or injury, to it, or oneself by plugging it to see if it works, when alarm bells, & experience say... it won't.

It has paper caps and probably crook electrolytics from sitting for a long period. Also with the 6BE6 and 6BA6 being pin not interchangeable that also risks damage. It may have been someone with a visual handicap that put the wrong tube in, but irrespective you are going to have to check the pin wiring. The IF transformer may be OK and was a sub for a fail. Pins 6BA6. 1, g1; 2, g2 IS; 3 & 4, Heaters; 5, anode; 6, Screen G2; 7, Cathode & its a pentode not a pentagrid.

Marc

The substitution is wrong two ways: the filament voltage/current and the basic nature of the two tubes: however, I'd bet my bottom dollar it works, maybe badly. The pinouts are so similar that the pentagrid converter will work as a pentode.

I don't call pin 2, 6BE6 cathode compared to Pin2, screen on 6BA6 exactly ideal.

Marc

Thanks for the insight. I've been buying parts radios here and there so I've built up a small selection of replacement tubes. How hard would it be to find the proper IF?

Check it more closely. Pin 2 is the suppressor grid on both tubes. In one case, it's connected to the cathode as is usual. I made that substitution once in an emergency.

I did check it again

The original post said that there was a 6BE6 in the 12BA6 hole, so much for the heaters The pinouts of the 12V tubes & 6V tubes appear to be the same.
According to: both of my tube manuals;

12BA6 1, g1; 2, g3 IS: 3&4 H: 5, Anode; 6, Screen 7, cathode

12BE6 1, g1; 2, K: 3 & 4, H: 5 Anode: 6, g2 g4: 7, Screen

So apart from cooking the heaters by sticking a 6V tube in a 12V hole. I reaaly fail to see thae whole show working at all well, if at all.

So I still would be getting out the "tooth pick, comb & circuit"

Marc

Pin 7 for 6/12BE6 is not a screen grid, but a control grid: the RF signal usually goes there, the oscillator working off grid 1, another control grid. Grids 2 and 4 are screens.

Awhile back I found I could use a 6BE6 instead of a 6BA6 as a regenerative detector by putting the signal on grid 1 and grounding grid 3 (grid 3 had to be grounded or else there was strong hum). Worked very nicely, btw.

So, putting aside the difference in heater voltage and current, if a 6BE6 was plugged into the AA5 12BA6 socket:

-the IF signal would go to control grid 1: that's OK.
-control grid 3 would be at RF ground, and close to DC ground: that's maybe OK (acts like a midway position suppressor?)
-the plate and screen would be connected properly: that's OK.
-the cathode and suppressor would be grounded: no bias, so that's not OK. Unless, somehow grid 1 develops contact bias. Grid 1 is connected to the AVC line through the IFT. The AVC line has a 3M resistor and eventually finds its way to ground through the volume control pot. That might be enough resistance for control grid 1 to develop contact bias!

It might work!

Rob

So the radio has been re-wired? I may be putting this one away until I get better with schematics.

How can you tell that the IF in question is not original to the set? Sometimes manufacturers had to sub components when standard was not available. Or a shop may have installed it properly in the past as a repair. I'd try to scope out the schematic and see if I could get the set working with a few changes before diving into a new IF.

You can see the tool marks from where the original was mounted. Thanks again for the help guys.

looks like one IF is slug tuning while the replacement is capacitor trimmer type. if it is the right frequency should be OK unless you are looking at a restoration job. seems unlikely to me. you should get the correct tube and check the wiring against a schematic. there are many models using this same tube configuration. very popular right before solid state radio designs. here is Zenith H511
http://www.nostalgiaair.org/PagesByMode ... 025551.pdf
you can sub a 12AV6 for the 12AT6 if you want more power output. more volume

It looks like there is a Philco part number on that replacement IF transformer.

This is an ideal set with which to learn how to read a schematic, and then proceed to wire it correctly.

Good point, I suppose I'll be cutting my teeth on this one.

That IF transformer if it is the proper frequency will work. I had to replace an IF transformer in a 1950's Zenith console with one pulled one from a junk radio chassis (forget make and model) and it works very good. I would rather prefer the IF transformers with the variable capacitors as they do not have the dreaded silver mica disease.

Previous thoughtful analysis notwithstanding, my opinion regarding the 6BE6 is that some idiot jammed in whatever fit the socket. A good set to learn on, if approached with the right attitude.

Dave Wise