PHANTOM RETUBED

[Sonar]

I retubed and gave the phantom a dusting. Paid $120 for 10 6LQ6's.
With 1 watt dk and 20 pep I'm showing 175 dk 800 pep on my Autek wm 1.
I'm driving the phantom with a sonar fs 2340, unamplified d104 and a Demco modulator. I think I got a great deal on the tubes. The ones I removed are original d&a stamped 6lq6's. I will eventually get them checked out as I'm sure most of them are good.
Unlike the old tubes the output doesn't drop after about 10 minutes of use and the watt meter seems to be more active. Thanks to all who advised me on how to change the tubes without getting myself electrocuted. p.s. even though I purchased a nos tube that is only there to complete the circuit I didn't put it in as the old one still lights up and is obviously doing what it's supposed to. Should I replace it? 73

 

[357]

The picture looks like the predriver is actually hooked up to me now....I think I made a mistake there saying it wasn't.

Those D&A tubes looked brand new compared to these

 

[Sonar]

The picture looks like the predriver is actually hooked up to me now....I think I made a mistake there saying it wasn't.

Those D&A tubes looked brand new compared to these

If it is indeed a driver I will replace it with the nos (tested) one I purchased. I was tempted to drop the new one in but after reading a couple of responses that it was there just to complete the circuit I thought it lights so it's doing its job.
I guess I should've went with my first intuition.
If it is indeed a driver the new one might be the way to go. I hope others weigh in.
I agree the original tubes look much better but one or more are obviously soft. I see it in the output.
I'm going to keep the old ones. I'm going to send them to Mikesradiorepair.
He will test them. If no body else weighs in on wheather that tube is a driver or not I might just put the new one in anyway.
The amps working excellent at the moment. I purposely left it on for about 8 hours after I put the tubes in and transmitted for a total of 45 minutes give or take a few.
The person I bought them from said he'd take them back at anytime if they didn't work out. So far so good. I'm thinking about hooking it up to the madison and hope there's some skip over the weekend. I use a Palomar 300a on the madison and it gets so much more use than the AM (phantom sonar) setup. Thanks for all your input. 73 p.s. I cropped a photo of that section of the circuit. I hope it helps someone figure out if that tube is a driver or not.

 

[ExitThirteen]

That little 6JG6A tube definitely looks like it's toast, replace that when you can. If you can't get a 6JG6A reasonable, you can substitute in a 6KV6A. It's a direct drop-in.

357, in the case of this particular model of Phantom, the 6JG6A tube is the "predriver" tube or the 1st stage in the "Triple Stage".

 

[Sonar]

That little 6JG6A tube definitely looks like it's toast, replace that when you can. If you can't get a 6JG6A reasonable, you can substitute in a 6KV6A. It's a direct drop-in.

357, in the case of this particular model of Phantom, the 6JG6A tube is the "predriver" tube or the 1st stage in the "Triple Stage".

I purchased a 6jg6a but a few people said it wasn't a driver. I should've dropped it in. I will do so tomorrow afternoon. I purchased it because I wasn't sure at that time if it just needed to be there in order to complete the circuit or it actually was a driver.
I've a feeling the phantoms going to hit the 1kw it once did.
I'm beginning to believe if I'd replaced that single tube first I probably wouldn't have needed the 6lq6's 'i purchased but I'm glad I got them anyway because they made a difference..
Can you tell me what Leeds you to believe the 6jg6a is toast? I'm not questioning you because I absolutely believe you're correct. I'd just like to know what I should look for as I've quite a bit of tube gear but no way to test tubes. I'm looking forward the results. I'll post them tomorrow evening. Big up's!! Thanks again. 73

 

[Tallman]

Are you sure that those electrolytic capacitors are wired correctly? I can't think of any applications in which that would be feasible. If those are supposed to be wired in series to increase the voltage rating, be prepared for some smoke some where in time.
If I'm wrong please educate me! Check page two of the link to the schematic.



http://www.cbtricks.com/Amp/d_and_a/phantom_triple_stage/graphics/phanton_triple_stage_sch_8-11.pdf

 

[Sonar]

Are you sure that those electrolytic capacitors are wired correctly? I can't think of any applications in which that would be feasible. If those are supposed to be wired in series to increase the voltage rating, be prepared for some smoke some where in time.
If I'm wrong please educate me!

View attachment 19419
View attachment 19423

Tallman. I've absolutely no idea. Like all my equipment, when it fails or needs repair I send it out.
I wish I could answer your question . I hope you're wrong. Nobody likes smoke. This amp was recapped about a year ago and it's worked very well since. No smoke!! I will forward your question to Mike of Mike's radio repair. He did the the refurb. Thanks 73

 

[Tallman]

I can't see the other side of the capacitors or enough detail to be sure, it just looks wrong. It probably is okay if the terminal it attaches to is isolated from ground.
Can you get some more photos? Just the area I cropped and both ends of the caps?

 

[Sonar]

I can't see the other side of the capacitors or enough detail to be sure, it just looks wrong. It probably is okay if the terminal it attaches to is isolated from ground.
Can you get some more photos? Just the area I cropped and both ends of the caps?

I'm going to drop a nos 6jg6a in sometime today. I'll take a better picture of those capacitors. For now this is the only picture.

 

[357]

Something looks odd.
Supposed to be 8 caps, 3 in series x2 parallel and 2 in series

 

[ExitThirteen]

The person that refurbished the amp used 600V capacitors, that's why there's only 6 capacitors instead 8. The idea of using 8 originally is because the original caps were rated at 350V apiece. Since it generates about 900V on on the high setting, it needs 3 x 350V caps to prevent the caps from blowing up from over-voltage, since 3 x 350V = 1050V. He uses 2 x 600V caps in this case, so 2 x 600V = 1200V. Substantially more headroom.

The original setup of 3/3/2 allows for a max of 1050V@33uf/1050V@33uf/700V@50uf.

What's required is 900V/450V per the schematic.

The current setup allows a max of 1200V@50uf/1200V@50uf/1200V@50uf, so with that being said, the current setup is a nice upgrade and will provide many years of service with no problems.

~Cheers~

 

[Sonar]

The person that refurbished the amp used 600V capacitors, that's why there's only 6 capacitors instead 8. The idea of using 8 originally is because the original caps were rated at 350V apiece. Since it generates about 900V on on the high setting, it needs 3 x 350V caps to prevent the caps from blowing up from over-voltage, since 3 x 350V = 1050V. He uses 2 x 600V caps in this case, so 2 x 600V = 1200V. Substantially more headroom.

The original setup of 3/3/2 allows for a max of 1050V@33uf/1050V@33uf/700V@50uf.

What's required is 900V/450V per the schematic.

The current setup allows a max of 1200V@50uf/1200V@50uf/1200V@50uf, so with that being said, the current setup is a nice upgrade and will provide many years of service with no problems.

~Cheers~

I actually recall Mike saying he upgraded the caps that.were in there but my knowledge is lacking to say the least so I really didn't know what he meant.
I was beginning to worry about using the amp until I heard back from Mike. It was baffling me because the refurbish was done about a year ago and it's been working fine. Thanks very much for clearing things up.
I did drop the nos 6jg6a in and it made no difference.
With 11/2 dk and (after a second look) about 17 pep I'm seeing 800. I'm happy with the amp and the way it's operating. Hopefully I won't need to do anything but turn it on and key it up.
Thanks again for clearing things up. 73.

 

[357]

The person that refurbished the amp used 600V capacitors, that's why there's only 6 capacitors instead 8. The idea of using 8 originally is because the original caps were rated at 350V apiece. Since it generates about 900V on on the high setting, it needs 3 x 350V caps to prevent the caps from blowing up from over-voltage, since 3 x 350V = 1050V. He uses 2 x 600V caps in this case, so 2 x 600V = 1200V. Substantially more headroom.

The original setup of 3/3/2 allows for a max of 1050V@33uf/1050V@33uf/700V@50uf.

What's required is 900V/450V per the schematic.

The current setup allows a max of 1200V@50uf/1200V@50uf/1200V@50uf, so with that being said, the current setup is a nice upgrade and will provide many years of service with no problems.

~Cheers~

That makes sense, thank you for taking the time to explain it.

 

[ExitThirteen]

No problem at all!

~Cheers~

 

[Robb]

This restoration of Sonar's amp is a fine example of solid workmanship and re-engineering.
Nice.

I don't know why the diode bridges/rectifiers are still set up that way, other than to keep it original.
Think I would have used a couple of large pre-fabbed rectifier blocks, so as allow some heat sinking to the chassis. Should do well enough - as is.