First sets of PCB arrived today. Thanks to Tom Browne for the great PCB work, and it worked first time round. The PCB can accommodate different FETs like 2SK170, BF862 and J310 to suit most of the requirements
If you’re interested in the final PCB let me know, production run shortly due to large number of request for this circuit for DHT preamps and drivers
Ale
Hi Ale,
Do you have protection zeners across the TO220? I think back to back (or face to face) are required for depletion FETS.
That’s the top device of the cascoded pair. Unless you’re screwing things up big time, the lower FET needs protection which Zener is provided
Hi Ale
looks like a nice job Tom has done. I use gyrator supply for the bias supply on my 211 amp. The boards were supplied by Rod Coleman. What is the voltage range and current they can deliver?
Hi Paul
Yes, its first prototype. I’ll probably make some adjustments to provide further flexibility on the capacitor sizes. This is my gyrator design for anode load use in a hybrid mu-follower. I use it in most of my DHT preamplifiers and drivers as it sounds amazing and provides a low output impedance and minimise distortion. It can be modified easily to be used as CCS anode load if desired.
The bottom jFET provides great HF response thanks to the low capacitance of the FET used instead of DN2540. In this PCB you have the flexibility of using TO-92 devices (e.g. J310 for high current or 2SK170 for low currents) as well as SMD device like the great BF862. Plenty of choices!
I have already received several requests over night and I have a handful of prototype PCBs at the moment 🙁
Cheers
Ale
Definitely sign me up for some, at least 4
Hi Ale,
I am interested to evaluate this design as load for a DHT linestage.
Send me details ho to get a couple of this boards.
Thanks
I would like to have 4 PCB’s if possilble !
I would also like to have some pcb’s (6) if/when possible
I would buy 4-6 of them.
Hi Ale,
I would be interested in four boards if possible
Hi Ale,
I would also like to have one pair Pcb’s if possible
Cheers
Nedim
I’d be interested in 4-6 boards also.
-Nick F
That looks really promising, good work !. I’d like to have 6 boards. Happy Christmas!
Günther
Hi Ale,
Nice work!
Count me in for 4 boards.
Regards,
Danny
Hi Ale,
I would like 4 PCB’s.
Best regards,
Kees.
Hi all,
Many thanks for the requests. There has been a lot of interest on these boards!
I will finalise the testing of the prototype PCB and will let you know when the updated PCB is going to production. I will get back to all the requests in due course.
Happy New Year to all!
Ale
Ale,
This is awesome….I’ll take 6.
Happy new year – and keep it up!
Steve
H Ale,
‘m plannng to build your 01A DHT preamp. May I have 4 sets please?
U’ve done great in the past, 2016 will be better! Keep it up!
Zekk