[Jamie]

I am working on a Wards Airline 62-418. The radio has been recapped and it plays fine. The problem is that the tuning eye does not open or close. It lights up about 3/4 of the way around and stays in that position no matter how strong the signal is. I have traced the schematic, following the control grid, plate, target and cathode. I found that R20 was open and replaced it, but it didn't help. Someone has previously been inside this set and they had replaced R22 with an 8M ohm resistor. I also corrected that by installing a 22M ohm (according to schematic).

Here is a link to the schematic - http://www.nostalgiaair.org/PagesByModel...011523.pdf

Any ideas would be appreciated! Thanks.

[Mondial]

What is the value of R22? It just says "meg" on the schematic.

Do you have negative AVC voltage at the junction of R9 and R21 when you tune in a station? If there is no negative voltage there, there will be no movement of the eye pattern and it will stay wide open.

[Jamie]

The value of R22? ... Good catch! .. I does not specify a value, neither does the parts list. I mistakenly looked at it and saw "22 Meg", which is wrong. It is R22. The one I replaced was 8M Ohm, so I will put that back in.

After replacing R22 with an 8M resistor, the voltage at R9 and R21 is 42mv dc.

[Mondial]

Does the voltage you measured change when you tune in a strong station? That seems to be the problem as you should have 10 to 20V negative there when receiving a strong station.

How about on the other side of R9, do you get any voltage reading there? Its possible R9 is open and voltage is not getting to the other side.

[morzh]

The grid voltage should change 0-20V or so.

[Jamie]

Voltage change is minimal tuning a station. I measured everything again, these are the results..

Junction of R21 and R22 is -.841v (when on station) -.790 (off station)
Junction of R21 and R9 is .9v
Junction of R9 and R10 is .7v

All of these resistors have been checked. The radio has not been aligned, but gets decent reception now.

[morzh]

Well, your AVC ain't functioning properly then.
Have you checked the resistors also (you did the recap)?
Have you checked all your tubes ?
Also: the 6K7 RF tube: check what seems to be C5 or C6 (grid return) - connects to G3 tube pin and R1 220 Ohm resistor.
And check the tube as well. Check them all.

[Mondial]

Jamie, if everything else checks out, do a full alignment. The AVC voltage is dependent on having enough gain in each stage to produce the rectified IF signal voltage at the detector. If the gain is low you may get some reception but not enough to generate sufficient AVC voltage.

So anything that reduces the reserve gain of the receiver like weak tubes, off value resistors, or misalignment will cause what you are experiencing.

[Jamie]

Thanks guys. I didn't follow my normal procedure of things with this radio. I guess I was too excited about working on the movie dial. I recapped it first, got it playing and checked voltages. Voltages were not perfect, but not dangerous levels either, so then I began working on the dial. Once that was fixed, I started on the tuning eye.

So, I haven't checked the tubes, gone through all the resistors or aligned it yet. I guess I put the cart before the horse...

[morzh]

There's nothing wrong with putting the cart before the horse: if the horse decided to fart, you are not gonna smell it.
(Like when you feed the horse beefaronie as they did it in "Seinfeld").

[Jamie]

Ok, update. I checked the tubes, and resistors, then did a full alignment. Success!! The tuning eye is now working. The alignment is what brought it to life. Thanks you guys!

Now, a question - I am not happy with the sensitivity of the tuning eye. I think this set was designed for use with a long wire antenna. It gets fine reception, actually very good, without an antenna. But the eye only closes all the way on the absolute strongest station, unless I connect an external antenna. Is there anything I can change to increase the sensitivity of the eye tube? Maybe a different value of a resistor? ... I would just like it better if the eye closed on weaker stations.

[morzh]

Basically the voltage of 0-20V moves the sector from 90 to 0 degrees.

You could possibly use a more sensitive tube. Like 6E5. It is pin-for-pin compatible but more sensitive, about twice - the voltage required to close the eye is 8V vs 20V at 250V plate voltage.

[Jamie]

Thank you. I will check my tube stash. I don't think I have a 6E5, but I will not know for sure unless I look. Just judging from performance on the bench, this radio is an excellent player. It really gets good reception. It played well before I aligned it, so I was very surprised to see it was so far out of alignment. Someone had screwed the adjustment screws all the way tight on the 2nd IF transformer. I finished up the cabinet today, so I will post a couple of photos when I put it all back together.

[Mondial]

Jamie, keep in mind that the eye tube acts a signal strength meter, not an absolute tuning indicator, so only the strongest stations should close the eye. If you make it too sensitive, the pattern will overlap and you loose the ability to use it as a tuning aid.

The 6U5/6G5 was specifically designed with a extended cutoff grid, so the pattern would not close or overlap on strong signals. You can make the tuning action somewhat more sensitive by removing the 8 meg resistor R22 and leaving it out or replacing it with the 22 meg that you previously installed.

[Jamie]

Thanks Mike!.. That's exactly what I needed to know. The tuning eye on this radio works perfectly when I hook up my external antenna, but the movement is minimal without it. On the other hand, the radio's reception is more than acceptable without the antenna hooked up. It's kind of like the eye tube needs the antenna, but the radio doesn't... I will try your modification tomorrow!