Larry's Phase Linear 700B

I have a $550 order coming from Mouser and I have another $250 order in the works. Everytime I send an order I remember 15 items immediately after I hit the "Order" button...

I measured the front end transistors using your method and the ones that matched on my meter, matched again, so the BE / BC process works for me too, it just takes a little longer. I still have a few out-liers at the top and bottom of the spectrum. If you want to send me your unmatched TIS97's I will try to match them and send you back matched pairs.
 
well i really don't have unmtched pairs separated. When I need some i throw a couple dozen on the bench and when I get 4 I like i put the rest back.
 
I take a more anal approach, wait - that didn't sound right... Anyway, I test all of mine at once and use Joe's styrofoam block to sort them based on hFE, low (400) to high (700). I stack the matched pairs together, that way I only have to test the transistors once. It saves time in the long run.

Hey, another thing - I was replacing the four original carbon composition (cc) 180 Ohm driver bias resistors in the 700B as I wait for my DC relay transformer from Mouser. Here is what I found:
Resistor (value)
1 - (185.3 Ohms)
2 - (182.3 Ohms)
3 - (178.9 Ohms)
4 - (234.2 Ohms) !!!!!!!!!!!!!!!!!!!!

These are the out of circuit measurements but the venerable Fluke 77 measured the same values in-circuit. So, I recommend change them all, the 180 Ohm metal film 1/2 Watt resistors are so cheap.

In the process, I used some aligator clip cables to facilitate holding the resistor carcasses. I found one of my 1 foot long clip cables was adding about 200 Ohms (more !!!!!!!!!!!!!!!!!!). So I tossed it and checked ALL my other cables, I have about 50 of 'em. They are all good. We can't afford to introduce errors like this. So my second recommendation is to check all your cables with a good digital VOM.

Lastly, I added some new volume pots to the 700B (I told you I was bored waiting for my Mouser order):
[attachment=0:1zxvtfn6]New Vol Pots.JPG[/attachment:1zxvtfn6]
 

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I have a set of alligator clip cables thbnat came with my Simpson 260 years ago. Every once in awhile I have to cut off an inch and resolder the clip to the leads. They started out 4 feet long. They are now just a wee bit longer than 2 feet. Still use em in my 179. On Suttopn's second 400 I had to replace all 4 also. One was in the megohm range.
 
speakerman1 said:
Makes me nervous you guys using my thread to experiment. LOL

Larry
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If that's all it takes to make you nervous, how did you live this long??
 
You have a Simpson 260! That makes me smile (grin). I used a Simpson 260 in the Navy and they were burret-proof and sailor-proof. Although it is possible to blow it up if you get across an 80 VDC 3000 A power supply. My current (no pun intended) analog meter is a Triplett Model 630-PLK and it is a Simpson 260 clone. I used one like it in high school shop and just fell in love with it. The back of the case is clear plastic, so cool.
 
I have 3 -260's all in various stages of blown up. They don't like voltage measurements in ohms mode.
 
Ya know Larrt.......that's possible!!!! I seem to have done the same thing, besides being shitass lucky!!!
 
The firstborn has made it back to the mancave. This is the project that got me registered at Phoenix. Didn't seem right not to post here, after all it was Larrt's amp.
It came back for some meters and the White Oak upgrade. I listened to it for a good ten hours Larrt. It sounds better than when it left, caps must have finally burned in. I'm gonna throw the newest White Oak board in, this can sound better.
 
How bout some Frequency response and some THD & N before we tear it down??
 

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laatsch55 said:
The firstborn has made it back to the mancave. This is the project that got me registered at Phoenix. Didn't seem right not to post here, after all it was Larrt's amp.
It came back for some meters and the White Oak upgrade. I listened to it for a good ten hours Larrt. It sounds better than when it left, caps must have finally burned in. I'm gonna throw the newest White Oak board in, this can sound better.
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LOL Who's amp is it now? LOL Are you going to swap the BGs? Is it still pushing 525 WPC?

Larry
 
Well it's your's of course. You said White Oak it if I thought it would improve it, it will improve it.Yep all the BG's will go on the White Oak board Larrt. Oh yeah, well above 500. Kept blowing 5 amp fuses, so we'll do some serious testing after Joe's board gets in it. Populating one tonight.
 
No, you weren't bumping up against a clip for 5 minutes either!!
 
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