[Patrick Turner]

On Wednesday, October 28, 2015 at 2:37:11 AM UTC-4, John L Stewart wrote:
Pink Floyd


A few, those of us that still dabble anyway. The long, cold winter is about to begin and I have half-a-dozen projects in the queue - mostly restorations.


Peter Wieck
Melrose Park, PA

Summer has just started here, with high probability we'll have a record number of days over 35C. ( 95F )

It won't be because every dude has an extra beer, and dozes off, leaving their tube amp on all night.

Anyway, I'm totally re-building an RF gene with tubes which I first made in 1997. This time I've armed my brain with Secret Knowledge known only by well paid HP boffins of 1955 who designed the HP606A RF gene. I'm at my limit, and I won't be trying to make an oscilloscope like the Tektronics 55 which starred in a video I watched recently. That Beast was reviewed by an oscilloscope collector, the truly compulsive collector of insanely complex old junk. All the other gathered oscilloscopes which sat around watching while this bloke told us all about the 55 all looked insanely jealous 'cos they were not getting the attention. Anyway, bloke rattled on and on and about the 110 tubes it had in two large boxes. He finally turned the darn Old Girl 55 ON, and it all came to life OK, and this sort of thing is the American Solution to Lonely Farnarkling in the Shed during your freezing winters which de-nuggets brass monkeys! Once the 55 runs, its T-shirt time while its -20C outside. Amazing what still lurks in countless basements and garages right across the USA. You can get every thing you want at the E lek Tronic resto ront.

My humble little gadget sure has tubes, but only about 8, plus a few bjts, because I'mm tryna combine benefits of tuned circuits with cathode modulation of a PP pair of 6EJ7 - or maybe EL86, and I should get a BD139 to do what one of a few 6B4 do in 606A, hopefully better, less THD in envelope shape..

I dunno how they'd do AM now, lots and lots and lots of utterly incomprehensible didgets & bizibots I guess.

I tried untuned circuitry with all SS, and frankly, the outcome compared to HP606A was quite appalling. Bandwidth stopped at 4MHz, and AM waves looked horrid above 2MHz, and probably, BF469 are NOT the ideal device to use for the modulator pair. NFB loops just would not work. I know - you don't have yell "Ain't ya heard about the latest HP function gene?" Much about HP I do like, but hasn't it all gone Chinese? Agilent stuff seems to have gone to China. I bought a new 117 Fluke DMM, better than oldun I had since '93. BUT, there's a bother with Vac reading, reads no lower than 22mV, and in mV range no lower than 4mV. BUT, another I tried at same shop reads down to zero with leads shorted OK. To get that Fluke fixed, its a pile of trouble I guess, or Sum Wonk in the Chines factory forgot to calibrate a pot properly.
so......... I was asked, "what do you think about Chinese Quality Control?"
and I answered "I was told they were to begin trials with that novel concept during next five year plan".

Oh, and if there's a whiff of Vdc while tryna read mVac with 117, she won't read properly, so I have to use an adapter I made for putting in 0.33uF and 330k to block the Vdc, then she's OK. Oldun read Vac OK regardless of presence of Vdc. Musta been a male voltmeter.

The Whirled won't disintegrate because of such trifling complaints.....

Patrick Turner.