Topics

RD16HHF1 power curve flattening...some

M Garza <mgarza896@...>
 

Dr. Schmidt,
It looks like the KST10 is the surface mount version of the KSP10.  It has the same specs as the MPSH10.

Marco - KG5PRT

On Mon, Mar 12, 2018 at 10:01 AM, K9HZ <bill@...> wrote:
Perfect Glenn.  Now if we can find current SMD parts to replace the 3904’s in place, this is a very nice upgrade. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com


email:  bill@...

 


On Mar 11, 2018, at 11:02 PM, Glenn <glennp@...> wrote:

I completed my mockup of the PA driver stages.

as previous post:
  • used MPSH10's in all stages. 
  • Used FT37-43 toroids all wound with 10 turns 0.25mm wire either tri- or bi-filar according to original Sch.
  • Bypassed all emitter resistors with a 220pF cap.
  • swept from C80 input to T10 secondary (as wound)

Result is a very flat response. Better than 1db from 3Mhz to 54MHz.

glenn
vk3pe
<uBITX_PA_driver_stages_all emitter res bypassed with 220pF 120318.jpg>


K9HZ <bill@...>
 

Perfect.  Thanks for that.  I will confirm and order some today for mods as soon as they come in. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com


email:  bill@...

 


On Mar 12, 2018, at 10:24 AM, M Garza <mgarza896@...> wrote:

Dr. Schmidt,
It looks like the KST10 is the surface mount version of the KSP10.  It has the same specs as the MPSH10.

Marco - KG5PRT

On Mon, Mar 12, 2018 at 10:01 AM, K9HZ <bill@...> wrote:
Perfect Glenn.  Now if we can find current SMD parts to replace the 3904’s in place, this is a very nice upgrade. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com


email:  bill@...

 


On Mar 11, 2018, at 11:02 PM, Glenn <glennp@...> wrote:

I completed my mockup of the PA driver stages.

as previous post:
  • used MPSH10's in all stages. 
  • Used FT37-43 toroids all wound with 10 turns 0.25mm wire either tri- or bi-filar according to original Sch.
  • Bypassed all emitter resistors with a 220pF cap.
  • swept from C80 input to T10 secondary (as wound)

Result is a very flat response. Better than 1db from 3Mhz to 54MHz.

glenn
vk3pe
<uBITX_PA_driver_stages_all emitter res bypassed with 220pF 120318.jpg>


K9HZ <bill@...>
 

Yeah thats correct. I ordered to MPSH10 TO92 form on Saturday to try this.  Getting several of my projects mixed up while on the road. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com


email:  bill@...

 


On Mar 12, 2018, at 10:24 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

All the *3904's in the driver stages are through-hole, the to92's have
a much higher max dissipation rating than the sot23's.
Jerry

On Mon, Mar 12, 2018 at 08:04 am, K9HZ wrote:
Perfect Glenn.  Now if we can find current SMD parts to replace the 3904’s in place, this is a very nice upgrade. 

Tim Gorman
 

Nice work!

Sounds like I need to get some mpsh10's or equivalent.

tim ab0wr

On Sun, 11 Mar 2018 21:02:34 -0700
"Glenn" <glennp@...> wrote:

I completed my mockup of the PA driver stages.

as previous post:

* used MPSH10's in all stages. 
* Used FT37-43 toroids all wound with 10 turns 0.25mm wire either
tri- or bi-filar according to original Sch.
* Bypassed all emitter resistors with a 220pF cap.
* swept from C80 input to T10 secondary (as wound)

Result is a very flat response. Better than 1db from 3Mhz to 54MHz.

glenn
vk3pe

Ashhar Farhan
 

A simple trick to buck the lower frequency gain is to use a low value capacitor in the emitter bypass of the predriver. The emitter will see a 100 ohms resistor at low frequncies and as the reactance of the emitter bypass falls with higher frequencies, the gain will increase.
- f

On 13 Mar 2018 12:10 am, "Tim Gorman" <tgorman2@...> wrote:
Nice work!

Sounds like I need to get some mpsh10's or equivalent.

tim ab0wr

On Sun, 11 Mar 2018 21:02:34 -0700
"Glenn" <glennp@...> wrote:

> I completed my mockup of the PA driver stages.
>
> as previous post:
>
> * used MPSH10's in all stages. 
> * Used FT37-43 toroids all wound with 10 turns 0.25mm wire either
> tri- or bi-filar according to original Sch.
> * Bypassed all emitter resistors with a 220pF cap.
> * swept from C80 input to T10 secondary (as wound)
>
> Result is a very flat response. Better than 1db from 3Mhz to 54MHz.
>
> glenn
> vk3pe




Glenn
 

Hi Ashhar, this is precisely what i have done in the driver stages. Along with the MPSH10's.
glenn
vk3pe

John <passionfruit88@...>
 

Thanks for the measurements Glenn.

Have you connected your driver stages to the finals in the uBitx and re-measured, or are you going to duplicate the final stage outside of the unit, or replace the current driver components in place?

Cheers and 73, John (VK2ETA)

Glenn
 

Hi John, no not yet. Plan is do that asap, duplicate the final stage with RD16HHF1's and hook up to my driver section..

Depending on how it all works of course, then mod my uBITX.

glenn

Nick VK4PP
 

Nice work Glen.

I am still to solve my oscillation issue on 20m+, but I have also decided to upgrade the LPF toroids to T50-6, I am concerned that the T30 will be overwhelmed at 20W output... Maybe need to do all the emitter 220 caps... and play with the feedback loop on the RD16.

I did order a bunch of the MPSH10 too. They have a different pinout to the 3904s? so have to go in the place twisted, like the RD16.... ?

73 Nick,

K9HZ <bill@...>
 

Nick... no need to upgrade those T30s.  Remember they only have to dissipate the harmonic power not the primary. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com


email:  bill@...

 


On Mar 13, 2018, at 7:39 PM, Nik VK4PLN <nickpullen@...> wrote:

Nice work Glen.

I am still to solve my oscillation issue on 20m+, but I have also decided to upgrade the LPF toroids to T50-6, I am concerned that the T30 will be overwhelmed at 20W output... Maybe need to do all the emitter 220 caps... and play with the feedback loop on the RD16.

I did order a bunch of the MPSH10 too. They have a different pinout to the 3904s? so have to go in the place twisted, like the RD16.... ?

73 Nick,

Glenn
 

Nick, yes the pin-out is different so you need to twist it around a bit. Easy done.

K9HZ <bill@...>
 

Hey Nick… did you make any progress?  I’ve been dying to dig into this but work keeps getting in the way of playing with my radios.  That’s gotta stop!

 

Something is up.  You can actually put another secondary winding on the PA transformer for negative feedback… That’s actually preferred.

 

I ran a couple simulations and the whole thing is stable without the feedback though (slightly lower gain though).

 

I sure like the 20+ watts out of those RD16 HHF1’s though and they are bullet proof.  I’ve never blown one out, and I’ve designed a lot of amplifiers with them and made a lot of mistakes with the “ON” switch in the “GO” position.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Yahoo Group.

 

email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Nik VK4PLN
Sent: Sunday, March 11, 2018 6:55 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RD16HHF1 power curve flattening...some

 

Well, i have dont my mods and powered up. Results are mixed:
Here are the mods.
RD16 replace IRF510.
New output transformer 1:4 BN43-3321 with a 330pf cap on input.
feed back resistors. from 22ohm to 1 K ohm
piggy backed R87 and R88 with 220pf capacitor.
RV1 full drive.

So results.
80M - 20W + ( blew my 2 Amp fuse)
40M - 18W - Seems stable.
30M - 17W BUT I get BAD feedback/ oscillation by just going PPT with no voice. The watt meter goes up to 18W!
20M - 15W  -  Same feedback issue
15M -  Same feedback issue.
10M -  Same feedback issue.

I have been thinking ans looking at other RD16 schematics, in alot of cases they dont use the feedback on the finals?
Also could this issue be cuase in the driver stage?

THanks guys, I am in over my head here....

73
10M - Same feedback issue


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Glenn
 

Nik,

I have done  a bit more testing now using an RD16HHF1 pair in the final although expediency meant i used the final section of the G6ALU 20W pa design.

I also found oscillation problem (about 110MHz). It seemed to be coming from the 1st and maybe the 2nd stages of the MPSH10 stages.  I removed the 330pF from the 1st stage and it's now pretty tame.  BUT, the response is nothing like as flat as I had hoped it would be. I have no feedback on the RD16HHF1 stages as yet.  I don't run the drive control flat output though as looking at the output on a scope, it's severely flat topping with this level. Around 16-17W is about max. level.

 But I did plot the response of an original complete G6ALU amp and it falls away badly at the 80M end of the HF bands. In the PicaStar where this pa is used, it's no problem as Star has software drive control on each band since its DSP based.

Not much time to investigate further at this stage.

glenn
vk3pe


MSG:
Well, i have dont my mods and powered up. Results are mixed:
Here are the mods.
RD16 replace IRF510.
New output transformer 1:4 BN43-3321 with a 330pf cap on input.
feed back resistors. from 22ohm to 1 K ohm
piggy backed R87 and R88 with 220pf capacitor.
RV1 full drive.

So results.
80M - 20W + ( blew my 2 Amp fuse)
40M - 18W - Seems stable.
30M - 17W BUT I get BAD feedback/ oscillation by just going PPT with no voice. The watt meter goes up to 18W!
20M - 15W  -  Same feedback issue
15M -  Same feedback issue.
10M -  Same feedback issue.

I have been thinking ans looking at other RD16 schematics, in alot of cases they dont use the feedback on the finals?
Also could this issue be cuase in the driver stage?

THanks guys, I am in over my head here....

73
10M - Same feedback issue

Nick VK4PP
 

THanks Glen.

I am making progress, got it working on 80,40,20, but still feedback on 15m, and 10m.
I put 220pf across all 7 emitor resistors. tried with and without, definitly a flatter output with. no effect on the feebback issue.
Changed back to the BN42-202, but a 2:4 ratio winding giving 1:4 transformation. Runs cool at 20+w with 330pf Mica cap. 1K feedback reistor.

80M - 22W
40M - 20W
20m - 18W

I did remove the SSM2167 Mic preamp and the feedback went away, but the mic output was very low... I then put in a MAX9814 mic chip/board via a BS170(same as the TX-POP setup) connected to the T/R line, To mute MIC on RX(DRAIN to GND on mic board..). Worked sortof. Got rid of the feed back, but when exiting TX I got a LOUD pop which causes the uC to reset?!?! so i removed the charge capacitor between GATE and SOURCE, Now the BS170 Switched off straight away, BUT the feedback is back ON TX.

I am thinking that the feedback is being caused by some sort of frequency interaction with the mic preamps and their power supply. Might be related to the TX-POP BS170 that is in the Audio path too...

Basically, the RD16 mods work. BUT when I intorduce any mods to the Mic amp side I start getting feedback. Adjusting RV1 reduced the feedback relative to power. SO I dont thiink I am overdriving the PA. I did try all number of combos of FB resistors and output transformer CAPS, and none made any difference in the feedback issue.
Also of not, is that if i Key CW, not feedback happens. I get full power, 22,20,18,16,14W... So if I can get the FB issue sorted Ill just stick to 20M and below on SSB and use the CW on the upper bands..

So Im thinking of using some inductors(filtering) in series with 5V to the Mic mute, as well as on the D7 pin thats triggering the BS170...

Any other suggestions?

73 Nick.

MVS Sarma
 

I fear the coupling is thro power line.
Please try star mode power line distribution.if possible have a Inductor based "pi" filter for the independent stages in power feed.


Regards
MVS Sarma
 

On Sun, Mar 18, 2018 at 1:57 PM, Glenn <glennp@...> wrote:
Nik,

I have done  a bit more testing now using an RD16HHF1 pair in the final although expediency meant i used the final section of the G6ALU 20W pa design.

I also found oscillation problem (about 110MHz). It seemed to be coming from the 1st and maybe the 2nd stages of the MPSH10 stages.  I removed the 330pF from the 1st stage and it's now pretty tame.  BUT, the response is nothing like as flat as I had hoped it would be. I have no feedback on the RD16HHF1 stages as yet.  I don't run the drive control flat output though as looking at the output on a scope, it's severely flat topping with this level. Around 16-17W is about max. level.

 But I did plot the response of an original complete G6ALU amp and it falls away badly at the 80M end of the HF bands. In the PicaStar where this pa is used, it's no problem as Star has software drive control on each band since its DSP based.

Not much time to investigate further at this stage.

glenn
vk3pe


MSG:
Well, i have dont my mods and powered up. Results are mixed:
Here are the mods.
RD16 replace IRF510.
New output transformer 1:4 BN43-3321 with a 330pf cap on input.
feed back resistors. from 22ohm to 1 K ohm
piggy backed R87 and R88 with 220pf capacitor.
RV1 full drive.

So results.
80M - 20W + ( blew my 2 Amp fuse)
40M - 18W - Seems stable.
30M - 17W BUT I get BAD feedback/ oscillation by just going PPT with no voice. The watt meter goes up to 18W!
20M - 15W  -  Same feedback issue
15M -  Same feedback issue.
10M -  Same feedback issue.

I have been thinking ans looking at other RD16 schematics, in alot of cases they dont use the feedback on the finals?
Also could this issue be cuase in the driver stage?

THanks guys, I am in over my head here....

73
10M - Same feedback issue


Lawrence Galea
 

Any rf decoupling at mic input and amp output?

On Mon, Mar 19, 2018 at 12:06 AM, Nik VK4PLN <nickpullen@...> wrote:
THanks Glen.

I am making progress, got it working on 80,40,20, but still feedback on 15m, and 10m.
I put 220pf across all 7 emitor resistors. tried with and without, definitly a flatter output with. no effect on the feebback issue.
Changed back to the BN42-202, but a 2:4 ratio winding giving 1:4 transformation. Runs cool at 20+w with 330pf Mica cap. 1K feedback reistor.

80M - 22W
40M - 20W
20m - 18W

I did remove the SSM2167 Mic preamp and the feedback went away, but the mic output was very low... I then put in a MAX9814 mic chip/board via a BS170(same as the TX-POP setup) connected to the T/R line, To mute MIC on RX(DRAIN to GND on mic board..). Worked sortof. Got rid of the feed back, but when exiting TX I got a LOUD pop which causes the uC to reset?!?! so i removed the charge capacitor between GATE and SOURCE, Now the BS170 Switched off straight away, BUT the feedback is back ON TX.

I am thinking that the feedback is being caused by some sort of frequency interaction with the mic preamps and their power supply. Might be related to the TX-POP BS170 that is in the Audio path too...

Basically, the RD16 mods work. BUT when I intorduce any mods to the Mic amp side I start getting feedback. Adjusting RV1 reduced the feedback relative to power. SO I dont thiink I am overdriving the PA. I did try all number of combos of FB resistors and output transformer CAPS, and none made any difference in the feedback issue.
Also of not, is that if i Key CW, not feedback happens. I get full power, 22,20,18,16,14W... So if I can get the FB issue sorted Ill just stick to 20M and below on SSB and use the CW on the upper bands..

So Im thinking of using some inductors(filtering) in series with 5V to the Mic mute, as well as on the D7 pin thats triggering the BS170...

Any other suggestions?

73 Nick.


John <passionfruit88@...>
 

Nik,

Agree with Lawrence here as I had feedback issues too on the higher frequency bands. I could minimise the feedback by using a better shielded microphone, but the issue would still be there on some bands (24 and 28Mhz in particular).

I placed a 100uH inductor (a Jaycar LF1534)  and a 1nF cap to the ground on the input of the SSM2167 and the feedback disappeared.

The test for me was to remove the microphone plug and get the uBitx in TX (SSB) and check that there was no power at the antenna. Then simply placing a short wire on the mic pin would trigger the feedback, but removing it would remove the feedback too. So I concluded that it was not an internal oscillation, but linked to RF getting into the mic input. This test might not be 100% certain but is a good pointer IMO.

73, John (VK2ETA)

Nick VK4PP
 

John,
Thanks for this, It makes perfect sense now, matches up with what I am getting too.

I will implement your fix tonight and report on the result...
So the inductor and cap are on the MIC input of the SSM2167? Not power?

73, Nick.

John <passionfruit88@...>
 

Hi Nik,

Correct, on the input pin of the SSM2167.

I don't seem to be getting feebback through the 5V supply from the Raduino. But I have it de-coupled with a resistor and capacitor. So I get about 4.8V to the SSM2167 and the MAX9814.

The current consumption is quite low. It only add about 2mA for each module when I plug them in.

All the best,

73, John (VK2ETA)

K9HZ <bill@...>
 

More simulations, tests, and part substitutions…

 

C261 & C262 changed to 0.01.  R261 & R262 changed to 750 ohms each.  Capacitors at the junction of R261 & L9, and R262 & L8 to ground of 560 pf each.  Resistors of 3.3Kohms from the gates of each RD16HHF1 to ground (this stabilizes the parts).  Change R97 and R98 to 300 ohm.  I did a lot of work on the output to match the transformer at higher frequency and I’ll tell you about that in another note, but these changes make the output completely stable and give me an output power of about 22 watts on each band 160-10 meters.  One additional thing I’ve tried is putting an additional drive stage before the PA consisting of a single ended RD16HHF1 to get about 1.7 watts to drive the two RD15HHF1s.  That results in 37 watts out.

 

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Yahoo Group.

 

email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Nik VK4PLN
Sent: Sunday, March 18, 2018 6:06 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RD16HHF1 power curve flattening...some

 

THanks Glen.

I am making progress, got it working on 80,40,20, but still feedback on 15m, and 10m.
I put 220pf across all 7 emitor resistors. tried with and without, definitly a flatter output with. no effect on the feebback issue.
Changed back to the BN42-202, but a 2:4 ratio winding giving 1:4 transformation. Runs cool at 20+w with 330pf Mica cap. 1K feedback reistor.

80M - 22W
40M - 20W
20m - 18W

I did remove the SSM2167 Mic preamp and the feedback went away, but the mic output was very low... I then put in a MAX9814 mic chip/board via a BS170(same as the TX-POP setup) connected to the T/R line, To mute MIC on RX(DRAIN to GND on mic board..). Worked sortof. Got rid of the feed back, but when exiting TX I got a LOUD pop which causes the uC to reset?!?! so i removed the charge capacitor between GATE and SOURCE, Now the BS170 Switched off straight away, BUT the feedback is back ON TX.

I am thinking that the feedback is being caused by some sort of frequency interaction with the mic preamps and their power supply. Might be related to the TX-POP BS170 that is in the Audio path too...

Basically, the RD16 mods work. BUT when I intorduce any mods to the Mic amp side I start getting feedback. Adjusting RV1 reduced the feedback relative to power. SO I dont thiink I am overdriving the PA. I did try all number of combos of FB resistors and output transformer CAPS, and none made any difference in the feedback issue.
Also of not, is that if i Key CW, not feedback happens. I get full power, 22,20,18,16,14W... So if I can get the FB issue sorted Ill just stick to 20M and below on SSB and use the CW on the upper bands..

So Im thinking of using some inductors(filtering) in series with 5V to the Mic mute, as well as on the D7 pin thats triggering the BS170...

Any other suggestions?

73 Nick.


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