PHANTOM 10 TUBE OR 9?

[Sonar]

After watching a couple of YouTube clips on the Phantom 10 tube, I actually noticed that there are 10 6lq6's, and the smaller tube that from my research convinces me is just there to either complete the circuit, or has something to do with the "CW" operation of the amp.
My Phantom only has 9 6lq6's, and the small peanut tube that as I mentioned completes the circuit, or has something to do with the supposed "CW" operation.
So is my triple stage tan colored d&a Phantom actually a 9 tube amplifier?
I've never heard anyone refer to the 10 tube Phantom as an 11 tube amplifier. So I'm assuming everyone that owns any of these Phantoms leaves out the small 10th, 11th, or 13th (if it's the 12 tube version) tube. For obvious reasons. This tube is not driving anything. I did at one time recall the number of that small tube, but it currently escapes me, and I didn't research it before I decided to ask the question about which amp I actually own.
Mine is a triple stage yet has three 6LQ6's driving 6 of the same.
The three or four 10 tube Phantoms I saw on YouTube actually had four 6LQ6's driving six of the same truly making it a 10 (ten) tuber.
Is the fact that mine has only nine 6lq6's make it an anomaly?
It does have other what I think to be deleted functions that mostly every one of the Phantom's I've ever seen have.
No preamp switch (BTL) or the switch for 10-20 (plastic plug in place) meter use on the reare. No band switch (plastic plug also.) 73

 

[nomadradio]

Okay, so around the time D&A changed their cabinet paint to brown, the noose, er, FCC rules were tightening around Ed Dulaney's neck.

The fiction that his stuff would work on the ham bands was a fig leaf over the private parts, so to speak. The band switch on the front wasn't connected to the amplifier's input side. That was still wired for 11 meters only.

When the 1979 rules took effect, he reworked his Maverick and Phantom as "MDX" and "PDX" CW-only ham transmitters. Instead of a "SSB" switch it had a socket for a crystal. And it had a socket for your morse-code key.

The rules that outlawed his linears did not apply to ham CW transmitters.

Once you bought one of these, an instruction sheet to convert it back to a CB linear would arrive in the mail a day or so later.

But to do this, one of the four driver tubes was re-purposed as the crystal oscillator, connected to that crystal socket. It was connected to drive the three remaining driver tubes. Early models still had four socket holes where you would expect them to be, but only three tube sockets. The "oscillator" tube had its own socket off nearer the center of the chassis.

The conversion would get you a three-driving six amplifier. That tenth "oscillator" tube still had to be in that socket. The Phantom splits 12.6 Volts between series-connected pairs of tube heaters. Can't run it with an odd number of tubes. The oscillator tube had to be in place so that all three heaters in the driver stage would light up.

It seems that this "fig leaf over the private parts" setup evolved, and later units had the tube-socket holes punched with only three socket holes where the driver tubes go.

But I don't know how many different intermediate "production change" versions are out there. Biggest pain was that they would leave out the input-matching circuit between the relay and the three driver tubes. The input-side SWR would be really high unless you added this function back to the amplifier in one way or another.

But it does have to have ten tubes in it, even though one of them does nothing more than light up its heater. It would probably work okay with only two driver tubes, but none of my customers ever liked that option.

Then again, maybe yours has a unique modification to get around this.

Pictures might help, might not.

73

 

[Sonar]

Okay, so around the time D&A changed their cabinet paint to brown, the noose, er, FCC rules were tightening around Ed Dulaney's neck.

The fiction that his stuff would work on the ham bands was a fig leaf over the private parts, so to speak. The band switch on the front wasn't connected to the amplifier's input side. That was still wired for 11 meters only.

When the 1979 rules took effect, he reworked his Maverick and Phantom as "MDX" and "PDX" CW-only ham transmitters. Instead of a "SSB" switch it had a socket for a crystal. And it had a socket for your morse-code key.

The rules that outlawed his linears did not apply to ham CW transmitters.

Once you bought one of these, an instruction sheet to convert it back to a CB linear would arrive in the mail a day or so later.

But to do this, one of the four driver tubes was re-purposed as the crystal oscillator, connected to that crystal socket. It was connected to drive the three remaining driver tubes. Early models still had four socket holes where you would expect them to be, but only three tube sockets. The "oscillator" tube had its own socket off nearer the center of the chassis.

The conversion would get you a three-driving six amplifier. That tenth "oscillator" tube still had to be in that socket. The Phantom splits 12.6 Volts between series-connected pairs of tube heaters. Can't run it with an odd number of tubes. The oscillator tube had to be in place so that all three heaters in the driver stage would light up.

It seems that this "fig leaf over the private parts" setup evolved, and later units had the tube-socket holes punched with only three socket holes where the driver tubes go.

But I don't know how many different intermediate "production change" versions are out there. Biggest pain was that they would leave out the input-matching circuit between the relay and the three driver tubes. The input-side SWR would be really high unless you added this function back to the amplifier in one way or another.

But it does have to have ten tubes in it, even though one of them does nothing more than light up its heater. It would probably work okay with only two driver tubes, but none of my customers ever liked that option.

Then again, maybe yours has a unique modification to get around this.

Pictures might help, might not.

73

Nomadd. Your knowledge never ceases to amaze me. The final pic is after recap.

 

[nomadradio]

Nice job, with one reservation.

We learned to put an equalizing/bleeder resistor across each HV filter cap when we replace them. You don't need six of them for the high-side filter caps.

A wire from where the top cap '-' side meets the middle cap's '+' side, and one from the bottom cap's +' side on each string of three to the other will put the two series strings of three caps in parallel with each other. Makes only three bleeders necessary, and two jumper wires.

A little easier than six bleeders on six capacitors.

We use a 220k 2 Watt, but the value is not critical. Just so all three in a string have the same resistance value. They serve both to divide up the HV equally three ways across the three series-connected caps, and to bleed them down when powered down.

73

 

[Sonar]

Nice job, with one reservation.

We learned to put an equalizing/bleeder resistor across each HV filter cap when we replace them. You don't need six of them for the high-side filter caps.

A wire from where the top cap '-' side meets the middle cap's '+' side, and one from the bottom cap's +' side on each string of three to the other will put the two series strings of three caps in parallel with each other. Makes only three bleeders necessary, and two jumper wires.

A little easier than six bleeders on six capacitors.

We use a 220k 2 Watt, but the value is not critical. Just so all three in a string have the same resistance value. They serve both to divide up the HV equally three ways across the three series-connected caps, and to bleed them down when powered down.

73

With the recommended Drive for this amplifier (4 DK 15(?) Pep) what would you say the output should be (in the high stage?)
For argument's sake let's say the tubes are brand new.
I'm trying not to be verbose, but I guess the best way to ask this question would probably be, what did this amp do out of the box (with proper drive?) 73 PS I haven't been using it for about three and a half months now, but when I did I always drove it with 11/2 dk 15 (AM) 12 SSB.

 

[nomadradio]

The pictures reveal that the driver stage is set up for zero bias. This is the factory-stock setup. It presents a dilemma for the driver tubes. If you reduce the radio's carrier too low, the plate current in those tubes will rise, cherry the tubes and fry the plate choke.


Like this one.

If you use enough carrier to keep the driver tubes happy, you'll hammer the final tubes with excess carrier power.

The fix for this is to lift pins 2 and 6 from ground. This can be tricky, if the lugs were bent over too sharply. Lifting them back up from the grounded metal saddle on the socket may break off the lug.

A .01uf disc cap goes to ground from each of the two grid pins on each socket. A wire is strung between the sockets to join the grids of the driver tubes to each other.

A 1k 5W (wirewound is okay) resistor goes to ground on one of the tube socket's grid pins. A 1N5408 or suitable rectifier gets its cathode (banded end) connected to a 6.3VAC heater pin. The anode end (no band) goes to the negative side of a 1000uf filter cap, with its positive end grounded. A second rectifier now gets the banded end to this junction of the first diode and filter cap. The anode end of this second rectifier goes to the nearest grid pin of the driver tubes. This second diode prevents the "grid leak" voltage that's rectified on the grids by your modulation peaks from charging up that filter cap. Without that second diode, this would charge that filter up to a bias voltage that cuts off the driver tubes until that charge bleeds off. Causes the carrier to "dive" during the pauses between words. Doesn't do the audio any favors, either.

This "dive" problem is why the bias filter cap will be too small in many old amplifiers, causing rectifier ripple to modulate your carrier when it's turned down. They made the filter small enough to prevent this behavior, but not large enough to filter out the "hum" sufficiently.

You may find that the input impedance of the driver tubes is now higher than it was before. If the input-side SWR is now too high, the tap point on the input coil that feeds the cathodes of the driver tubes might need to be moved upwards away from ground by one turn. That's usually enough to get the input-side SWR back below 1.5 or so.

This "roasted driver choke" problem also occurs when someone tries to use a Maverick or Phantom on sideband. The tubes just are not biased for SSB and want to overheat when they're keyed with no drive.

Of course there is a much-easier and cheaper answer to this issue. Simply connect the driver plate choke to the low-side B+ voltage full-time. So long as the driver tubes are always on "Low" side, they won't overheat.

But none of my customers was ever interested in reducing the peak power on High side just to keep their tubes from roasting. Doesn't reduce it more than 20 or 30 percent, as a rule.

But that will fix the problem just by moving a wire from the High/Low switch directly to the Low-side filter caps.

D&A could have included this feature, but nobody had a radio with a carrier control when this box was designed. And if adding more parts won't make it sell better, they get left out.


With reasonably-fresh 6MJ6 tubes in a Phantom, you might see upwards of 800 Watt peaks. ShouId see 500 or 600 at least. I never recommend more than one-quarter of the amplifier's PEP for the carrier-power level. Setting the radio's carrier to keep the High-side carrier output below 200 Watts is what I would recommend.

Whether that will be 2.5 Watts, 1.75 or 2.01367 Watts is anybody's guess. The exact radio drive power is not what's important. The amplifier's output carrier is what you need to use as a target for setting the radio's carrier drive.


73

 

[Sonar]

The pictures reveal that the driver stage is set up for zero bias. This is the factory-stock setup. It presents a dilemma for the driver tubes. If you reduce the radio's carrier too low, the plate current in those tubes will rise, cherry the tubes and fry the plate choke.


Like this one.

If you use enough carrier to keep the driver tubes happy, you'll hammer the final tubes with excess carrier power.

The fix for this is to lift pins 2 and 6 from ground. This can be tricky, if the lugs were bent over too sharply. Lifting them back up from the grounded metal saddle on the socket may break off the lug.

A .01uf disc cap goes to ground from each of the two grid pins on each socket. A wire is strung between the sockets to join the grids of the driver tubes to each other.

A 1k 5W (wirewound is okay) resistor goes to ground on one of the tube socket's grid pins. A 1N5408 or suitable rectifier gets its cathode (banded end) connected to a 6.3VAC heater pin. The anode end (no band) goes to the negative side of a 1000uf filter cap, with its positive end grounded. A second rectifier now gets the banded end to this junction of the first diode and filter cap. The anode end of this second rectifier goes to the nearest grid pin of the driver tubes. This second diode prevents the "grid leak" voltage that's rectified on the grids by your modulation peaks from charging up that filter cap. Without that second diode, this would charge that filter up to a bias voltage that cuts off the driver tubes until that charge bleeds off. Causes the carrier to "dive" during the pauses between words. Doesn't to the audio any favors, either.

This "dive" problem is why the bias filter cap will be too small in many old amplifiers, causing rectifier ripple to modulate your carrier when it's turned down. They made the filter small enough to prevent this behavior, but not large enough to filter out the "hum" sufficiently.

You may find that the input impedance of the driver tubes is now higher than it was before. If the input-side SWR is now too high, the tap point on the input coil that feeds the cathodes of the driver tubes might need to be moved upwards away from ground by one turn. That's usually enough to get the input-side SWR back below 1.5 or so.

This "roasted driver choke" problem also occurs when someone tries to use a Maverick or Phantom on sideband. The tubes just are not biased for SSB and want to overheat when they're keyed with no drive.

Of course there is a much-easier and cheaper answer to this issue. Simply connect the driver plate choke to the low-side B+ voltage full-time. So long as the driver tubes are always on "Low" side, they won't overheat.

But none of my customers was ever interested in reducing the peak power on High side just to keep their tubes from roasting. Doesn't reduce it more than 20 or 30 percent, as a rule.

But that will fix the problem just by moving a wire from the High/Low switch directly to the Low-side filter caps.

D&A could have included this feature, but nobody had a radio with a carrier control when this box was designed. And if adding more parts won't make it sell better, they get left out.


With reasoably-fresh 6MJ6 tubes in a Phantom, you might see upwards of 800 Watt peaks. ShouId see 500 or 600 at least. I never recommend more than one-quarter of the amplifier's PEP for the carrier-power level. Setting the radio's carrier to keep the High-side carrier output below 200 Watts is what I would recommend.

Whether that will be 2.5 Watts, 1.75 or 2.01367 Watts is anybody's guess. The exact radio drive power is not what's important. The amplifier's output carrier is what you need to use as a target for setting the radio's carrier drive.


73

Sounds good. With 11/2 dk I see about 170 and 630 pep on both the autek WM1's I own.
Next time I use it I'll exsperiment with a DK between 2 and 4 Watts.
I can say that I've checked the tubes even after being a bit long-winded (on AM and SSB) and no sign of that cherry color did I ever see from the original d&a stamped 6lq6's.
After getting some advice about the coil not being messed properly I decided to put the amp away until I had the chance to box it up and send it out. The guy who did the restoration on it is totally qualified. On the other hand I think that you may have some more knowledge about the way these particular amplifiers should be restored. That's not to say that the person who works on all my equipment doesn't know what he's doing. He's absolutely top-notch. But it seems as if you obviously have a long-lived relationship with these amplifiers that he may not, and I will print and forward all your above replies to him. After that it's in his hands and I totally trust what he does. Thanks for your time nomad. 73 my friend
PS I sent you a p.m. a while back asking if you would consider taking this in and working your magic on it. I have since learned that you do not do mail in work. If by some chance you would consider working your magic on my Phantom it would be my pleasure to send it to you.

 

[Ronnie Hatfield]

hello i have a 10 tube D &a phantom i have 2 resistor thats bad what is the watt on them? the color is tan black red silver one is located where the ac cord comes in and the other one on the other side of the caps thanks

 

[nomadradio]

Sounds like the grid-return resistors. One set for the driver tubes, another for the final tubes. Brown-black-red indicates a resistance of 1000 ohms, often abbreviated to "1k". The silver band indicates a ten-percent tolerance. Means the part can measure anywhere between 900 and 1100 ohms and still meet its specification.

The original ones are rated at 2 Watts.

I hope you don't anticipate this will be the sole, solitary only thing you find that's wrong.

An amplifier that's 45 or more years old tends to have a laundry list of stuff that's either worn out or deteriorated from age alone.

Unless it's a barn find with 500 original miles. Then all you have to worry about are the age issues.

73