Hi huggygood,
For a MOSFET source follower it is important to use a MOSFET with lhe lowest Crss possible, today they are a lot
As an example the FQPF2N60C ( https://www.mouser.fr/datasheet/2/308/FQPF2N60C-1306298.pdf ) has 4.3 pF and the STU9HN65M2 ( https://www.st.com/resource/en/datasheet/stu9hn65m2.pdf ) has 0.85 pF
There are others, like the FQPF8N60CFT (12 pF), the STF2N80K5 (0.5 pF
) ( https://www.st.com/resource/en/datasheet/stf2n80k5.pdf ), and the STF7N60M2 (0.68 pF 
) ( https://www.st.com/resource/en/datasheet/stf7n60m2.pdf )
I have bought 10 pieces of each of them to make tests as they are not very expensive
Regards,
Marc
For a MOSFET source follower it is important to use a MOSFET with lhe lowest Crss possible, today they are a lot
As an example the FQPF2N60C ( https://www.mouser.fr/datasheet/2/308/FQPF2N60C-1306298.pdf ) has 4.3 pF and the STU9HN65M2 ( https://www.st.com/resource/en/datasheet/stu9hn65m2.pdf ) has 0.85 pF
There are others, like the FQPF8N60CFT (12 pF), the STF2N80K5 (0.5 pF
) ( https://www.st.com/resource/en/datasheet/stf2n80k5.pdf ), and the STF7N60M2 (0.68 pF ) ( https://www.st.com/resource/en/datasheet/stf7n60m2.pdf )I have bought 10 pieces of each of them to make tests as they are not very expensive
Regards,
Marc
Hi Vunce,
Yes you only need to put the jumper as indicated on the schema
As you are using DC I suggest to connect the GND to the input which is connected to pin 9 when using a 6N1P tube, but it is not critical...
Bye,
Marc
PS : I have squeezed the PCB in less than 10 cm, but to do that I removed the pot which was not very useful on board anyway
Yes you only need to put the jumper as indicated on the schema
As you are using DC I suggest to connect the GND to the input which is connected to pin 9 when using a 6N1P tube, but it is not critical...
Bye,
Marc
PS : I have squeezed the PCB in less than 10 cm, but to do that I removed the pot which was not very useful on board anyway
Hi All. I need to put all high and low voltage recitifer and low voltage regulator with AC power source into individual case. Due to my amp case not large enough and want less pay $ for my another tube amp (it can reuse this DC supply). I am not sure this arrangement, all DC given from seperated box will have any problem and concern that i need pay more attention in advance ?
Hi ckwong99,
For the EL34 Baby Huey, you can use DC or AC voltage for the high voltage (max 275 VAC or 385 VDC if using 400 V capacitors) and for the 6.3 V heater, BUT YOU MUST USE ONLY AC for the 50 V bias & driver supply because the positive AND the negative voltage are rectified on board from the AC input
The power supply for the preamplifier is serial type and fixed by 3 x 100V Zener, of course it is possible to use different Zener values
I have also made a variable one with a regulator, see picture...
Rgds,
Marc
For the EL34 Baby Huey, you can use DC or AC voltage for the high voltage (max 275 VAC or 385 VDC if using 400 V capacitors) and for the 6.3 V heater, BUT YOU MUST USE ONLY AC for the 50 V bias & driver supply because the positive AND the negative voltage are rectified on board from the AC input
The power supply for the preamplifier is serial type and fixed by 3 x 100V Zener, of course it is possible to use different Zener values
I have also made a variable one with a regulator, see picture...
Rgds,
Marc
Attachments
Updated BOM for EL34 & EL84 Baby Huey
Hi Happy Baby Huey Builders,
To make your DIY work easier, I have made a new updated BOM for both EL34 and EL84 Baby Huey PCB
I do not plan to make a separate thread for the EL84 Baby Huey because both versions are very similar and I think it is better to have all the information in only one thread.
For those who are interested by the history of the EL84 Baby Huey, they can read here EL84 Amp - Baby Huey the long thread started by Ian (gingertube) in 2006 !!! This is where all started for me in October 2016 (post 1670), 10 years after the first post, and at that time I would not have believed that more than 500 PCB that I have designed will be built, I didn't even know how to make a Group Buy and hopefully after the two first GB of 200 boards, Prasi accepted to continu the job and has produced 300 boards more
Now the Baby Huey story is finished for me and I hope to have the time in 2019 to make my long delayed Quad KT120 with Cathode feedback and autobias
Merry Christmas and Happy New year,
Marc
Hi Happy Baby Huey Builders,
To make your DIY work easier, I have made a new updated BOM for both EL34 and EL84 Baby Huey PCB
I do not plan to make a separate thread for the EL84 Baby Huey because both versions are very similar and I think it is better to have all the information in only one thread.
For those who are interested by the history of the EL84 Baby Huey, they can read here EL84 Amp - Baby Huey the long thread started by Ian (gingertube) in 2006 !!! This is where all started for me in October 2016 (post 1670), 10 years after the first post, and at that time I would not have believed that more than 500 PCB that I have designed will be built, I didn't even know how to make a Group Buy and hopefully after the two first GB of 200 boards, Prasi accepted to continu the job and has produced 300 boards more
Now the Baby Huey story is finished for me and I hope to have the time in 2019 to make my long delayed Quad KT120 with Cathode feedback and autobias
Merry Christmas and Happy New year,
Marc