Phantom 12 tube uf changes

[Jimbo165]

I was talking to a phantom 12 tube owner and he said he got even more out of D&A 12 tube amp when he changed 100uf 350v capacitors to 220uf 450v , amplifier had alot more audio and more pep has anyone else made this type of changes. Owner said tubes got a little warmer and he did not drive amp as much but it had increased power and audio increase was real noticeable. Thanks 165 from the Great Lakes

 

[W5LZ]

Just from your description it sounds like those capacitors are in the power supply. I'm not too sure I'd put a lot of 'faith' in that having much affect on signal quality or power output levels. It could have, but...
- 'Doc

 

[wavrider]

hi microfarad rating caps will stabilize the HV ps some what.

More audio?

It only amplifies what is put in.

There might have been a noticeable difference if the older caps were weak allowing the HV to sag under load.

 

[Wiskey Delta-40]

There might have been a noticeable difference if the older caps were weak allowing the HV to sag under load.

I will agree here.. If there was some bad caps, yes new ones would make a difference.

Other wise changing the HV caps just because, you are waisting your time and $$

 

[psycho]

I was talking to a phantom 12 tube owner and he said he got even more out of D&A 12 tube amp when he changed 100uf 350v capacitors to 220uf 450v , amplifier had alot more audio and more pep has anyone else made this type of changes. Owner said tubes got a little warmer and he did not drive amp as much but it had increased power and audio increase was real noticeable. Thanks 165 from the Great Lakes

What does he claim the 12 tuber does in output now?

 

[Jimbo165]

Psycho I am running 6km6 tubes in amp and radio 3w to 12w swing does not drive amp. I am getting 600 pep watts out of amp but have tryed a different radio that swings 2w to 30w and amp goes 750+ put a jb150 in front of amp using my radio and watts go to 800 to 900w. I have already put new 100uf 450v capacitors in amp already but another gentleman had told me about him using the 220uf 450v caps and he got 200w more and greatly increased audio I was just asking if anyone else had done this and did they get same results. I have another 12 tube on bench now that needs caps. Maybe I will try them and compare 12 tubes on watts and audio results. I have had 7 phantom amps come across my bench in last 1 1/2 years and have never seen a 3w to 12w radio of mine take any of those amps to 750 to 850w that everyone says they do but maybe I just have a tight meter or ? who knows? Thanks for your comments and info.

 

[n0zna]

I would never put a JB12 into a phantom...to much swing and dk...I have a phantom i run everyday on 10 and 12mtrs...and run a rci2950dx or a rci2980wx at 5 pep and have changed the caps in pwr supply to 220 500v and stability on voltage is great...and also there is no s meter streght gain between 500 and 800 pep its a joke...200 to 500,500 too 1k double pwr for s meter ratings...

 

[Jimbo165]

12 tube uf changes

n0zna
I can turn deadkey on my jb150 from 1w to 20w but I run a deadkey of 3w swinging to 100w into 12 tuber as of right now I do this because I do not have a radio that puts out wattage like your RCIs that can drive amplifier. I see that you did change caps to a 220uf 500v this is what I was asking about at start of post. You said you have more voltage stability but did it also increase your audio? I was told that this change would increase it enough that people could hear difference also did it increase the heat output of tubes any? I agree that pep watts are not most important thing I have people around me putting out more watts but donot get near the contacts I do or the ease of talking to skipland but it is always better to have more than enough than not enough. I thank you very much for your info and hope to get more about capacitor changes.

 

[n0zna]

Thats to much swing into the amp is what im saying...

 

[Shockwave]

Thats to much swing into the amp is what im saying...

I thought the same thing too. Then I considered how many sweep tube amps used 1 driving 3 driving 6 tubes. The 12 tube Phantom has 4 driving 8. This tube configuration can easily handle one more tube to drive the first four. That is not to say the power supply and output tank circuit are up to the job or that the tubes will last nearly as long as they would without the driver. It does suggest this particular amp may not be as grossly over driven by the JB-150 as it might first appear.

At least he is keeping the carrier at the stock level and this greatly reduces the demand on the amp by only having to reproduce larger positive peaks. Make sure the fan is not restricted because this level of PEP drive will increase the heat dissipated by the tubes but not nearly as much as increasing the carrier by a proportional amount. Since the small power supply caps would be the first noticeable weak link in terms of producing this peak power, it makes sense to upgrade them.

I'd also replace the 40+ year old rectifier diodes because they are going to be stressed a lot more on power up with the larger filter caps. Upgrading power supply caps in a situation where we are only increasing the peak demand on the power supply can make an increase in the audio. This is simply because the larger filter caps can provide the current needed to reproduce the positive peaks that have a short duration which allows them to recharge during reduced carrier and negative peak conditions.