Topics

Need Clarification on uBitx v. 4 Schematic

Mike
 

Regarding the new version 4 schematic:

Do new components Q942 and Q952 connect in parallel with the IRF510's as per schematic or
are the RD15HV's meant to be used as an alternative to the IRF510's?

Thanks,
Mike



-Mike

MVS Sarma
 

i suppose that RD16HHF1 are to be used.  Some people experiment with RD15HVF1 too. They feel that 21 and 28 mhz performance would improve.
but you might suffer poor performance at 80m band etc


Regards
MVS Sarma
 

On Thu, May 31, 2018 at 9:50 AM, Mike <msmith@...> wrote:
Regarding the new version 4 schematic:

Do new components Q942 and Q952 connect in parallel with the IRF510's as per schematic or
are the RD15HV's meant to be used as an alternative to the IRF510's?

Thanks,
Mike



-Mike


Jerry Gaffke
 

In answer to Mike's question, the RD15*/RD16* parts are an alternative to the IRF510's.
But they are not magical, just stuffing them into the uBitx will not improve things by much,
there are a number of mods required to make good use of them. 
And considerably more mods required to address the issue of getting sufficient gain
at 30mhz from the preceding  2n3904 stages.  

I suggest waiting for Allison and others to arrive at a good recipe 
before blindly butchering boards.

Jerry


On Wed, May 30, 2018 at 10:27 pm, Mvs Sarma wrote:
i suppose that RD16HHF1 are to be used.  Some people experiment with RD15HVF1 too. They feel that 21 and 28 mhz performance would improve.
but you might suffer poor performance at 80m band etc
 

Regards
MVS Sarma
 
. . .

 

On Thu, May 31, 2018 at 9:50 AM, Mike <msmith@...> wrote:
Regarding the new version 4 schematic:

Do new components Q942 and Q952 connect in parallel with the IRF510's as per schematic or
are the RD15HV's meant to be used as an alternative to the IRF510's?

Thanks,
Mike

Dexter N Muir
 

To my eye, it looks like parallel, though I'm left wondering how they'd mount. The RDs would have better 10/12m performance, the IRFs better at 80/40m. Not quite sure on biasing/static currents, but sure interested.

K9HZ <bill@...>
 

ALTERNATIVE

 

 

Dr. William J. Schmidt - K9HZ

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Mike
Sent: Wednesday, May 30, 2018 11:21 PM
To: BITX20@groups.io
Subject: [BITX20] Need Clarification on uBitx v. 4 Schematic

 

Regarding the new version 4 schematic:

Do new components Q942 and Q952 connect in parallel with the IRF510's as per schematic or
are the RD15HV's meant to be used as an alternative to the IRF510's?

Thanks,
Mike



-Mike

 

Virus-free. www.avg.com

Mike
 

Thanks for the replies . . . I figured they were meant to be options. May be better just to provide a text-box footnote in schematic.

I've made dozens of FT8 contacts with a scratch built ubitx(V3) using the 510's, typically 10W PEP,  minimal heatsink, no fan, no enclosure . . . . the 510's are actually quite rugged, stable, and predictable.

It's part of what makes it a fun build - they're cheap to replace when you drive them into oscillation and then *poof* !

Michael Shreeve
 

I believe Ashhar is using the RD15HV IN rV4 . he ha done major mods, A complete descrete direct coupled audio amplifier circuit, a pop eliminator, an AGC , Lots of stuff. He claimed it was a dollars worth of parts, but, the board is a massive change. The Finals section in the schematic is very confusing and looks like a direct coupled Mosfet circuit, but that's probably not the case. Hopefully he's reading this , I printed the schematic 10x17 today and the changes stood out like a "western sore thumb" . Very tempting to have a second board. 

On Thu, May 31, 2018 at 2:46 PM, Mike <msmith@...> wrote:
Thanks for the replies . . . I figured they were meant to be options. May be better just to provide a text-box footnote in schematic.

I've made dozens of FT8 contacts with a scratch built ubitx(V3) using the 510's, typically 10W PEP,  minimal heatsink, no fan, no enclosure . . . . the 510's are actually quite rugged, stable, and predictable.

It's part of what makes it a fun build - they're cheap to replace when you drive them into oscillation and then *poof* !




--
Michael Shreeve N6GRG

Michael Shreeve
 

Oh, and the pop eliminator looks like a 2n7000 board controlled by the T-R line. On a separate little board, much more simple than others I've seen. Five components total includes the mosfet. And a new test point TP1 ! And new jumpers where the little board connects. I haven't put the two 10X17 sheets side by side yet , and these still stand out.  A 1uf with a diode and resistor give the mute timing just enough time. 

On Thu, May 31, 2018 at 3:43 PM, Michael Shreeve <shreevester@...> wrote:
I believe Ashhar is using the RD15HV IN rV4 . he ha done major mods, A complete descrete direct coupled audio amplifier circuit, a pop eliminator, an AGC , Lots of stuff. He claimed it was a dollars worth of parts, but, the board is a massive change. The Finals section in the schematic is very confusing and looks like a direct coupled Mosfet circuit, but that's probably not the case. Hopefully he's reading this , I printed the schematic 10x17 today and the changes stood out like a "western sore thumb" . Very tempting to have a second board. 

On Thu, May 31, 2018 at 2:46 PM, Mike <msmith@...> wrote:
Thanks for the replies . . . I figured they were meant to be options. May be better just to provide a text-box footnote in schematic.

I've made dozens of FT8 contacts with a scratch built ubitx(V3) using the 510's, typically 10W PEP,  minimal heatsink, no fan, no enclosure . . . . the 510's are actually quite rugged, stable, and predictable.

It's part of what makes it a fun build - they're cheap to replace when you drive them into oscillation and then *poof* !




--
Michael Shreeve N6GRG




--
Michael Shreeve N6GRG

Michael Shreeve
 

Its looking like the 2n7000 mosfet board completely shuts off the tx to clear the pop. But, I cannot find a modification that would account for Ashhar's description of a AGC which has something to do with the IF. The little board isn't removed from the circuit and is in operation when strong signals audio go through, so perhaps it limits them ? Or perhaps the schematic at rfsignals.com doesn't include the AGC ? 

On Thu, May 31, 2018 at 3:51 PM, Michael Shreeve <shreevester@...> wrote:
Oh, and the pop eliminator looks like a 2n7000 board controlled by the T-R line. On a separate little board, much more simple than others I've seen. Five components total includes the mosfet. And a new test point TP1 ! And new jumpers where the little board connects. I haven't put the two 10X17 sheets side by side yet , and these still stand out.  A 1uf with a diode and resistor give the mute timing just enough time. 

On Thu, May 31, 2018 at 3:43 PM, Michael Shreeve <shreevester@...> wrote:
I believe Ashhar is using the RD15HV IN rV4 . he ha done major mods, A complete descrete direct coupled audio amplifier circuit, a pop eliminator, an AGC , Lots of stuff. He claimed it was a dollars worth of parts, but, the board is a massive change. The Finals section in the schematic is very confusing and looks like a direct coupled Mosfet circuit, but that's probably not the case. Hopefully he's reading this , I printed the schematic 10x17 today and the changes stood out like a "western sore thumb" . Very tempting to have a second board. 

On Thu, May 31, 2018 at 2:46 PM, Mike <msmith@...> wrote:
Thanks for the replies . . . I figured they were meant to be options. May be better just to provide a text-box footnote in schematic.

I've made dozens of FT8 contacts with a scratch built ubitx(V3) using the 510's, typically 10W PEP,  minimal heatsink, no fan, no enclosure . . . . the 510's are actually quite rugged, stable, and predictable.

It's part of what makes it a fun build - they're cheap to replace when you drive them into oscillation and then *poof* !




--
Michael Shreeve N6GRG




--
Michael Shreeve N6GRG




--
Michael Shreeve N6GRG

Jack, W8TEE
 

JackAl has both IF and audio AGC. This photo:

Inline image

was taken at the FDIM conference. If you look closely, the graph above the speech compressor shot (sort of column 3, row 2, going from left to right, top to bottom) shows the rolloff for the AGC. Unfortunately, Al's got the JPG's for the plots. Put it this way: It's pretty good.

Jack, W8TEE

On Thursday, May 31, 2018, 9:45:14 PM EDT, Michael Shreeve <shreevester@...> wrote:


Its looking like the 2n7000 mosfet board completely shuts off the tx to clear the pop. But, I cannot find a modification that would account for Ashhar's description of a AGC which has something to do with the IF. The little board isn't removed from the circuit and is in operation when strong signals audio go through, so perhaps it limits them ? Or perhaps the schematic at rfsignals.com doesn't include the AGC ? 

On Thu, May 31, 2018 at 3:51 PM, Michael Shreeve <shreevester@...> wrote:
Oh, and the pop eliminator looks like a 2n7000 board controlled by the T-R line. On a separate little board, much more simple than others I've seen. Five components total includes the mosfet. And a new test point TP1 ! And new jumpers where the little board connects. I haven't put the two 10X17 sheets side by side yet , and these still stand out.  A 1uf with a diode and resistor give the mute timing just enough time. 

On Thu, May 31, 2018 at 3:43 PM, Michael Shreeve <shreevester@...> wrote:
I believe Ashhar is using the RD15HV IN rV4 . he ha done major mods, A complete descrete direct coupled audio amplifier circuit, a pop eliminator, an AGC , Lots of stuff. He claimed it was a dollars worth of parts, but, the board is a massive change. The Finals section in the schematic is very confusing and looks like a direct coupled Mosfet circuit, but that's probably not the case. Hopefully he's reading this , I printed the schematic 10x17 today and the changes stood out like a "western sore thumb" . Very tempting to have a second board. 

On Thu, May 31, 2018 at 2:46 PM, Mike <msmith@...> wrote:
Thanks for the replies . . . I figured they were meant to be options. May be better just to provide a text-box footnote in schematic.

I've made dozens of FT8 contacts with a scratch built ubitx(V3) using the 510's, typically 10W PEP,  minimal heatsink, no fan, no enclosure . . . . the 510's are actually quite rugged, stable, and predictable.

It's part of what makes it a fun build - they're cheap to replace when you drive them into oscillation and then *poof* !




--
Michael Shreeve N6GRG




--
Michael Shreeve N6GRG




--
Michael Shreeve N6GRG