Mine worked also with no resistor changes and around 13.5 mA. But the voltages around the cascode were much lower because of that (around 4V) and IIRC also Vc>Vb>Ve did not hold up anymore. I don't know if it makes a difference if the drain voltage for the jfets is 4V in stead of 6V. Less gain? More noise? Working outside of their most linear region? With my ear to the speaker I thought the version with lower R1 value had less hiss, but that is not scientific, because the gain might have been be slightly different, and some time had passed between the 2 versions.
The reason I asked about cascode saturation in the first place is something I observed on LTspice. As I understand it, one of the objects of a cascode is to provide a constant voltage to the drain of the lower transistor.
The first pic shows Vq5c and Vq5e with Vce ~ 300mV, then ~150mV, ~70mV. The cascode performance seems to be compromised as Q5 saturates.
The first pic shows Vq5c and Vq5e with Vce ~ 300mV, then ~150mV, ~70mV. The cascode performance seems to be compromised as Q5 saturates.
If you don't have a socket and need to test some SOT-23 devices immediately, I found that coating the eraser of an ordinary yellow pencil with rubber cement and letting that dry completely, gives you a nicely adhesive piston. It will both pick and place and hold the Device Under Test in steady contact with the PCB footprint lands, while you perform your electrical measurement(s). Sure, it's a cheap kludge. But you can use it right now, today, while you wait for your fancy Zero Insertion Force test sockets to arrive from Switzerland or Singapore. And it actually works.
Some brands of rubber cement prefer to call their product "contact cement", including my favorite: Weldwood.
Some brands of rubber cement prefer to call their product "contact cement", including my favorite: Weldwood.
I used a fancy zero insertion force socket (I think I bought it from Alltronics), but it was not as easy to position as I had hoped. Perhaps due to my ham fists and maybe I need to update the prescription on my reading glasses 
One tip I found on the DCA75 is to take 3 readings and average, I observed some variance in the last digit for the Idss.
One tip I found on the DCA75 is to take 3 readings and average, I observed some variance in the last digit for the Idss.
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Hello All,
AT Burning Amp last fall I got the impression that the lifetime purchases of 2sk170 are nearing depletion, we are living longer than expected. As a result we will need to get used to our little surface mount friends and learn to solder and test them.
For my learning process I like to build breadboards. A few weeks back I bought 100 2SK209 that were already soldered to small bits of copper clad adaptor boards. I have soldered leads to these little 2SK209 adaptor boards. I have some of these ready to plug into sockets on the test Pearl 3 on my bench. The 2SK170 will unplug and the 2SK209 will take their place to see how they compare plugged into the exact same test Pearl 3; gain, distortion and noise kind of stuff.
I have been fiddling with the PEAK test socket. All that touching and placing the 2SK209 in the socket is a lot of effort. Plus all the touching adds a lot of heat to confuse the measurements.
Similar to Mark's method I have placed the surface mount jfets on the test PCB pads and held them down for the duration of the idss test with the pointed end of a cuticle orange stick. *
Thanks DT
* https://www.amazon.com/Orange-Cuticle-Remover-Manicure-Pedicure/dp/B01GLSY71W
I agree avoiding saturation is best or starting to pull current out of the base emitter junction.
My beloved SL-1100 went on the fritz last night for an undiscovered reason. No output.
Swapped in my backup deck. An SL-1300 that hasn’t been powered on in 14 years! Popped in the cart and head shell from the SL-1100. Works wonderfully with the P3. Auto start and return still work!
All Good.
Swapped in my backup deck. An SL-1300 that hasn’t been powered on in 14 years! Popped in the cart and head shell from the SL-1100. Works wonderfully with the P3. Auto start and return still work!
All Good.
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Running with the LME49702 today.
I'm taking a pre employement drug test next week ( I thought I was retired but... )
So, can I fail the drug test by listening to Pink Floyd, Meddle, Echoes? Will I test positive for psychedelics?
I mean, you wanna go DO the 70s?
You got your Gong Show in there and all the Whale Sounds you can ever want and need.
The P3 is fascinating. Not only is the bass kit fast... (And no, I wasn't listening to the Maggies) but the steeliness and metallic decay of the gong is astounding. It's real. You can hear the decay of the gong while it is hit again. Hard to explain (1), I might want to meditate with this preamp.
The drum kit is also amazing. You can hear the skin.... and the bass drum is ALIVE. It's really there.
This preamp has no mushiness at all: it's sharp without overhanging; the midrange is NOT overripe, just spot on; treble sounds tight and extended, with no smearing.
This from an LP I bought back in '75 or so. (Always kept clean).
How much does a hit of LSD run nowadays?
I miss the old Gong Show.
(1) We have a Japanese altar at home, with a gong. You gotta hit the gong twice - unless you're at the Temple.... the gong sounds just climb into a combo of decay and initial attack. It's a superposition of sounds. The monks can keep it up for a minute - and then they segue into an Amada Buddha chant. I need a record of a Buddhist Temple.
I'm taking a pre employement drug test next week ( I thought I was retired but... )
So, can I fail the drug test by listening to Pink Floyd, Meddle, Echoes? Will I test positive for psychedelics?
I mean, you wanna go DO the 70s?
You got your Gong Show in there and all the Whale Sounds you can ever want and need.
The P3 is fascinating. Not only is the bass kit fast... (And no, I wasn't listening to the Maggies) but the steeliness and metallic decay of the gong is astounding. It's real. You can hear the decay of the gong while it is hit again. Hard to explain (1), I might want to meditate with this preamp.
The drum kit is also amazing. You can hear the skin.... and the bass drum is ALIVE. It's really there.
This preamp has no mushiness at all: it's sharp without overhanging; the midrange is NOT overripe, just spot on; treble sounds tight and extended, with no smearing.
This from an LP I bought back in '75 or so. (Always kept clean).
How much does a hit of LSD run nowadays?
I miss the old Gong Show.
(1) We have a Japanese altar at home, with a gong. You gotta hit the gong twice - unless you're at the Temple.... the gong sounds just climb into a combo of decay and initial attack. It's a superposition of sounds. The monks can keep it up for a minute - and then they segue into an Amada Buddha chant. I need a record of a Buddhist Temple.
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I made it through my career without a drug test.
One time I showed up to the construction site with my laptop and roll of construction documents in hand. The contractor pointed to the trailer for drug testing. I thanked them and headed back to my truck.
They followed me out and said Okay you can come on site if they walked with me, what I was expecting in the first place.
^ Well.... in my field they require them pretty often.
Which doesn't bother me much I guess.
The first time was in '90 (or so). I was wearing a nice shirt, slacks and jacket at the interview and they offered me the contract on the spot, I was asked to go down to the Company Nurse and "donate".
So I went down and met Brunhilda... German American Tank: The Panzer Of Nurses.
She told me to strip to my underwear and go into a bathroom and fill the cup. Huh? I was wearing clean boxers, so it wasn't too bad. In I went and when done I tried to wash my hands. Water had been shut down.
I went outside and told her the water wasn't running... she told me that was done on purpose.
OK, I handed her my specimen and told her: "Well, I sort of spilled some around it so I tried to wipe it down".
LOLOLOLOL
Which doesn't bother me much I guess.
The first time was in '90 (or so). I was wearing a nice shirt, slacks and jacket at the interview and they offered me the contract on the spot, I was asked to go down to the Company Nurse and "donate".
So I went down and met Brunhilda... German American Tank: The Panzer Of Nurses.
She told me to strip to my underwear and go into a bathroom and fill the cup. Huh? I was wearing clean boxers, so it wasn't too bad. In I went and when done I tried to wash my hands. Water had been shut down.
I went outside and told her the water wasn't running... she told me that was done on purpose.
OK, I handed her my specimen and told her: "Well, I sort of spilled some around it so I tried to wipe it down".
LOLOLOLOL
yeah, I'm running way too much gain in my system.
The Macho 252 SIT has a lot of gain (28db)... and the CJ preamp drives the F4 perfectly (25db gain, 20Vrms output)...so you can figure that... The Grado outputs 1mV so the P3 is set for "medium gain"....
For sure, my current setup doesn't lack in dynamics.
... Cloudless everyday
You fall upon my waking eyes
Inviting and inciting me to rise
And through the window in the wall
Come streaming in on sunlight wings
A million bright ambassadors of morning
And no one sings me lullabies
And no one makes me close my eyes
So I throw the windows wide
And call to you across the sky ...
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Kit update -
There’s a good number of kits enroute to the fulfillment company and should be ready to sell sometime next week.
No idea how fast they will sell out, if they sell at the same rate as the previous batch, it will be about 2hr.
Many more will be made, everybody will have a chance to build this incredible project. Might have to wait a bit, bit we’ll get it done.
There’s a good number of kits enroute to the fulfillment company and should be ready to sell sometime next week.
No idea how fast they will sell out, if they sell at the same rate as the previous batch, it will be about 2hr.
Many more will be made, everybody will have a chance to build this incredible project. Might have to wait a bit, bit we’ll get it done.