Re: RD16HHF1 in the uBITX
#ubitx
?The old fashioned solution for capacitive loading was simply to put an inductor in parallel tuned to the desired frequency, to cancel it out.? ?
In my ancient vacuum tube rigs, they do that in the driver and final amplifier stages, and I get about the same power all the way from 80 meters through 15 meters, and in some rigs through 10 meters.? ??
Maybe they were on to something?? ?Perhaps there is a way to take that technique and apply it to semiconductor systems with some semiconductor switches to adjust component choices?
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As reported here:??
an LTSpice model of Q90, Q911,Q912, Q92,Q93,Q96,Q97
shows that with the IRF510 gates clipped free of the circuit,
the signal available to the final in volts is about 77% at 30mhz what it is at 7mhz.
Power available is down by the square of the voltage, or about 60%.
LTSpice is probably assuming worst case 2n3904 parameters.
This result will not be fixed by going to RD16HHF1's.
With the IRF510 gates tied back in, the drop in signal became much more pronounced
due to capacitive loading by the IRF510's.? They need to be driven harder for good results at 30mhz.
Jerry, KE7ER
|
Advice on selling Bitx40 on EBay
I have an unbuilt Bitx40 and many accessories that I no longer have the time to build and am looking for advice about setting a price on EBay.?
It is one of the early versions, Serial Number 156, that came without a Raduino, which I purchased later and would be included.?
I also purchased a 10:1 potentiometer with a companion turns counter, a Buck Booster to boost the voltage for the final stage, a QRPguys Digital Dial Frequency Counter and two PLJ-6LED Frequency Displays (one in Red and one in Blue. Finally there is a nice square gold tone aluminum cookie tin measuring 6x6x2 3/4.?
Altogether I spend over $100 for all these items. My question is, if I ask $100 for all one EBay, is that too much or too little?
Any advice would be most appreciated.?
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Re: RD16HHF1 in the uBITX
#ubitx
As reported here:?? /g/BITX20/message/40938an LTSpice model of Q90, Q911,Q912, Q92,Q93,Q96,Q97 shows that with the IRF510 gates clipped free of the circuit, the signal available to the final in volts is about 77% at 30mhz what it is at 7mhz. Power available is down by the square of the voltage, or about 60%. LTSpice is probably assuming worst case 2n3904 parameters. This result will not be fixed by going to RD16HHF1's. With the IRF510 gates tied back in, the drop in signal became much more pronounced due to capacitive loading by the IRF510's.? They need to be driven harder for good results at 30mhz. Jerry, KE7ER
|
Re: RD16HHF1 in the uBITX
#ubitx
Thanks vk2eka. Very informative study of the rd16hhf1 in a microbitx!?
72/73 de Chas ai4ot
On Feb 15, 2018, at 9:16 AM, Gordon Gibby < ggibby@...> wrote:
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John, thank you for that extremely well documented information. Makes me much more interested in considering this. I wonder if the efficiency indicates that the circuit design could be improved?
I have done a strait replacement of the IRF510s with RD16HHF1s.?
?
Here are the before and after values I got.
?
All tests done with uBitx VR1 drive level in the same position of approx 60% of range.
?
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final.?
(For info, Rx currents: 164mA no volume, about 209mA "normal" volume).?
- At 7.1Mhz:? ?10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,? therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
?
?
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A.?
(For info, Rx currents: 188mA no volume, about 230mA "normal" volume).?
- At 7.1Mhz:? 19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A
?
?
I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements.
I will reset mine to probably the 400-450mA value I read from some articles.
?
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current).?
- At 7.1Mhz:? 10W,? PA current: 1.20A
- At 14.2Mhz: 9W,? ?PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
?
?
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current).?
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
?
?
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current).?
- At 7.1Mhz:? 13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,? ? PA current: 1.38A
- At 28.1Mhz: 9.5W,? PA current: 1.79A
?
?
?
Interesting observations:
?
A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band.
?
B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies.
?
C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume
a higher bias (within limits) is preferable? Any risk of thermal runaway?
?
D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency
seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s.
?
E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs.
?
F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive
feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity).
?
?
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1
and TDA2822).
?
To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place.
?
It would be interesting to compare these results with others who performed the finals swap on the stock uBitx.
?
Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.
This is a lot of fun.
?
All the best,
?
73, John (VK2ETA)
?
<IMG20180215233124.jpg>
|
Re: Toshiba Output Transistors for ubitx
#ubitx
|
I believe option #2 will work with 4 powerpoles?as well - at least that's how I used 'em. Cheaper, too.
To increase stiffness, you'll have to pin each of the sets together - I use the little black pin to lock each pair, although I understand you can use zipties too.
And yeah - works fine and looks better if the two clamps are on the interior.
Mike Yancey, KM5Z
Dallas, Texas
|
Re: RD16HHF1 in the uBITX
#ubitx
John,
Thanks for this great info!
I like your cross legged RDs :-)
Raj
At 15-02-2018, you wrote:
toggle quoted message
Show quoted text
I have done a strait replacement
of the IRF510s with RD16HHF1s.
?
Here are the before and after values I got.
?
All tests done with uBitx VR1 drive level in the same position of approx
60% of range.
?
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A
total (factory setting) so assume 100mA in each final.
(For info, Rx currents: 164mA no volume, about 209mA "normal"
volume).
- At 7.1Mhz:?? 10W, total current: 1.79A, of which PA current:
1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current:
1.0A,? therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A,
therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A,
therefore main board current 0.42A
?
?
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current
checked at 0.21A.
(For info, Rx currents: 188mA no volume, about 230mA "normal"
volume).
- At 7.1Mhz:? 19W, total current: 2.65A, of which PA current: 2.09A,
therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A,
therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A,
therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A,
therefore main board current 0.42A
?
?
I haven't found a definitive reference for the safe and optimum values of
the RD16HHF1s idle bias current but it seems to range from 200 to 500mA.
So I would not recommend long term usage of the 500mA bias I used for
these measurements.
I will reset mine to probably the 400-450mA value I read from some
articles.
?
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A
PA idle current).
- At 7.1Mhz:? 10W,? PA current: 1.20A
- At 14.2Mhz: 9W,?? PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
?
?
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA
idle current).
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
?
?
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA
idle current).
- At 7.1Mhz:? 13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,??? PA current: 1.38A
- At 28.1Mhz: 9.5W,? PA current: 1.79A
?
?
?
Interesting observations:
?
A. The RD16HHF1 produces a much flatter power curver over frequency (in
my device), although it shows a dip somewhere near the 15m band.
?
B. The IRF510 can produce some nice power in the lower frequencies when
increasing the PA supply voltage, but it comes at the price of a steep
power drop at higher frequencies.
?
C. The bias does not seem to influence the efficiency of the finals at
full power with RD16HHF1, since biasing at 250 and 500mA produces
essentially the same output for the same DC power input. Assuming
distortion reduces with higher bias, can we assume a higher bias (within
limits) is preferable? Any risk of thermal runaway?
?
D. The board main current (which includes the current in the driving
stages of the power amplifier) does not seem to change with frequency
from 20m onwards. Is this because the gain is pretty constant? If so,
most of the drop in power with increasing frequency seems to be in the
IRF510s, supporting the results obtained with the RD16HHF1s.
?
E. With the current uBitx PA circuit the RD16HHF1 seems limited in
output, although not having the proper test equipment I can't say where
the limitation occurs.
?
F. When I increased the drive through VR1 I noticed that at around 40%
for the lower frequencies and at around 60% for the top frequencies I get
a compression effect and the output does not increase much more from
there on. I left it at 60% and got a positive feedback on the voice
quality on my first QSO on 40m. Therefore I assume that the
compression/clipping is not significant at that level (but I can't
measure the sprectral purity).
?
?
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I
can say I have reached my goal just by changing the finals to RD16HHF1s
and supplying the board with 13.8VDC (below the 15.2/15V stated in the
respective datasheets of the RD16HHF1 and TDA2822).
?
To replace the finals I simply cut the legs of the IRF510s about 3mm
above the board and correspondingly cut and crossed over the drain and
source pins of the RD16s to match, then soldered in place.
?
It would be interesting to compare these results with others who
performed the finals swap on the stock uBitx.
?
Next is the installation of the TPA2016 audio amplifier with I2C
controllable AGC.
This is a lot of fun.
?
All the best,
?
73, John (VK2ETA)
?
![[]](/g/BITX20/attachment/41916/)
|
Re: Toshiba Output Transistors for ubitx
#ubitx
Do you have a link to the video?
Thanks
Marco - KG5PRT?
On Feb 15, 2018 8:17 AM, "Walter" < W9KJO@...> wrote: Recently on a youtube video it was suggested that Toshiba output transistors might provided a little more power out for the ubitx.
Does someone have the actual part number for the transistors being referred to??
What other changes would be required in the ubitx for this modification?
73, thanks
Walter
W9KJO
|
Re: RD16HHF1 in the uBITX
#ubitx
John,
thanks for the intensive research on the PA stage.
To my experience the RD16HFF1 really need a very high quiescent current of about 500 mA each--- not good for a QRP design.
The output transformer plays an important role in the design. Normally a 1 to 4 impedance transformation (12.5 ohms to 50 ohms) is suffficient. Each transistor "sees" half of the impedance i.e. 6.25 ohm. The windings of the tranformer must be capacitively compensated and for the windings the so called leakage inductance mimimized.
Another big issue is the choke for the supply voltage: the common used center tapped transformer without the choke is nor recommended.
Ashar Farhan uses two isolated chokes, to my experience a bifilar wound choke is the better choice.
I never reached output powers above 10 W on my designs, e.g. the G6ALU design useed in teh PIC A STAR and more or less copied by G6LBQ.
I tried a Guanella type transformer with 25 ohm coax cable plus a balun on its output, the result was disappointing.
I never got output powers above 10 W
For a good balanced design all even order harmonics (2nd, 4th etc) should be minimal.
Sorry folks, even after long and intensive experiments I can not give You THE optimal design!
Henning Weddig
DK5LV
Am 15.02.2018 um 15:15 schrieb Gordon Gibby:
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Show quoted text
John, thank you for that extremely well documented information. Makes me much more interested in considering this. I wonder if the efficiency indicates that the circuit design could be improved?
On Feb 15, 2018, at 08:39, John <passionfruit88@... <mailto:passionfruit88@...>> wrote:
I have done a strait replacement of the IRF510s with RD16HHF1s.
Here are the before and after values I got.
All tests done with uBitx VR1 drive level in the same position of approx 60% of range.
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final.
(For info, Rx currents: 164mA no volume, about 209mA "normal" volume).
- At 7.1Mhz:? ?10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,
therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A.
(For info, Rx currents: 188mA no volume, about 230mA "normal" volume).
- At 7.1Mhz:? 19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A
I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements.
I will reset mine to probably the 400-450mA value I read from some articles.
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current).
- At 7.1Mhz:? 10W,? PA current: 1.20A
- At 14.2Mhz: 9W,? ?PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current).
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current).
- At 7.1Mhz:? 13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,? ? PA current: 1.38A
- At 28.1Mhz: 9.5W,? PA current: 1.79A
Interesting observations:
A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band.
B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies.
C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume a higher bias (within limits) is preferable? Any risk of thermal runaway?
D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s.
E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs.
F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity).
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1 and TDA2822).
To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place.
It would be interesting to compare these results with others who performed the finals swap on the stock uBitx.
Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.
This is a lot of fun.
All the best,
73, John (VK2ETA)
<IMG20180215233124.jpg>
|
Re: RD16HHF1 in the uBITX
#ubitx
That¡¯s exactly what it means.? The efficiency is dropping as the frequency is increasing indicating that some of the components in the RF chain are not optimal.? Again what is needed here is for someone to scope the drive BEFORE the PA and report the voltage levels at each frequency.? I¡¯ve intended to do this for a while but am caught up on other build projects for the uBITx¡ ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Yahoo Group. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Thursday, February 15, 2018 8:16 AM
To: [email protected]
Subject: Re: [BITX20] RD16HHF1 in the uBITX #ubitx? John, thank you for that extremely well documented information. Makes me much more interested in considering this. I wonder if the efficiency indicates that the circuit design could be improved? I have done a strait replacement of the IRF510s with RD16HHF1s.? Here are the before and after values I got. All tests done with uBitx VR1 drive level in the same position of approx 60% of range. 1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final.? (For info, Rx currents: 164mA no volume, about 209mA "normal" volume).? - At 7.1Mhz:? ?10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A - At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,? therefore main board current 0.39A - At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A - At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A 2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A.? (For info, Rx currents: 188mA no volume, about 230mA "normal" volume).? - At 7.1Mhz:? 19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A - At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A - At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A - At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements. I will reset mine to probably the 400-450mA value I read from some articles. 3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current).? - At 7.1Mhz:? 10W,? PA current: 1.20A - At 14.2Mhz: 9W,? ?PA current: 1.21A - At 21.2Mhz: 4.5W, PA current: 0.65A - At 28.1Mhz: 5.5W, PA current: 0.95A 4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current).? - At 7.1Mhz: 10W, PA current: 1.18A - At 14.2Mhz: 9W, PA current: 1.26A - At 21.2Mhz: 5W, PA current: 0.71A - At 28.1Mhz: 6W, PA current: 1.11A 5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current).? - At 7.1Mhz:? 13.5W, PA current: 1.95A - At 14.2Mhz: 13.5W, PA current: 1.93A - At 21.2Mhz: 6W,? ? PA current: 1.38A - At 28.1Mhz: 9.5W,? PA current: 1.79A Interesting observations: A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band. B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies. C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume a higher bias (within limits) is preferable? Any risk of thermal runaway? D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s. E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs. F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity). So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1 and TDA2822). To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place. It would be interesting to compare these results with others who performed the finals swap on the stock uBitx. Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.
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Toshiba Output Transistors for ubitx
#ubitx
Recently on a youtube video it was suggested that Toshiba output transistors might provided a little more power out for the ubitx.
Does someone have the actual part number for the transistors being referred to??
What other changes would be required in the ubitx for this modification?
73, thanks
Walter
W9KJO
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Re: RD16HHF1 in the uBITX
#ubitx
John, thank you for that extremely well documented information. Makes me much more interested in considering this. I wonder if the efficiency indicates that the circuit design could be improved?
toggle quoted message
Show quoted text
I have done a strait replacement of the IRF510s with RD16HHF1s.?
?
Here are the before and after values I got.
?
All tests done with uBitx VR1 drive level in the same position of approx 60% of range.
?
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final.?
(For info, Rx currents: 164mA no volume, about 209mA "normal" volume).?
- At 7.1Mhz:? ?10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,? therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
?
?
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A.?
(For info, Rx currents: 188mA no volume, about 230mA "normal" volume).?
- At 7.1Mhz:? 19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A
?
?
I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements.
I will reset mine to probably the 400-450mA value I read from some articles.
?
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current).?
- At 7.1Mhz:? 10W,? PA current: 1.20A
- At 14.2Mhz: 9W,? ?PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
?
?
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current).?
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
?
?
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current).?
- At 7.1Mhz:? 13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,? ? PA current: 1.38A
- At 28.1Mhz: 9.5W,? PA current: 1.79A
?
?
?
Interesting observations:
?
A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band.
?
B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies.
?
C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume
a higher bias (within limits) is preferable? Any risk of thermal runaway?
?
D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency
seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s.
?
E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs.
?
F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive
feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity).
?
?
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1
and TDA2822).
?
To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place.
?
It would be interesting to compare these results with others who performed the finals swap on the stock uBitx.
?
Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.
This is a lot of fun.
?
All the best,
?
73, John (VK2ETA)
?
<IMG20180215233124.jpg>
|
Re: RD16HHF1 in the uBITX
#ubitx
I have done a strait replacement of the IRF510s with RD16HHF1s.?
?
Here are the before and after values I got.
?
All tests done with uBitx VR1 drive level in the same position of approx 60% of range.
?
1. IRF510s and main board at 12.1V. PA idle current checked at 0.20A total (factory setting) so assume 100mA in each final.?
(For info, Rx currents: 164mA no volume, about 209mA "normal" volume).?
- At 7.1Mhz:? ?10W, total current: 1.79A, of which PA current: 1.31A, therefore main board current 0.48A
- At 14.2Mhz: 5.5W, total current: 1.39A, of which PA current: 1.0A,? therefore main board current 0.39A
- At 21.2Mhz: 2.2W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
- At 28.1Mhz: 1.3W, total current: 0.95A, of which PA current: 0.53A, therefore main board current 0.42A
?
?
2. IRF510s with 16.5V, 13.8V for main board. PA total idle current checked at 0.21A.?
(For info, Rx currents: 188mA no volume, about 230mA "normal" volume).?
- At 7.1Mhz:? 19W, total current: 2.65A, of which PA current: 2.09A, therefore main board current 0.56A
- At 14.2Mhz: 11W, total current: 2.20A, of which PA current: 1.80A, therefore main board current 0.40A
- At 21.2Mhz: 5.5W, total current: 1.40A, of which PA current: 1.00A, therefore main board current 0.40A
- At 28.1Mhz: 2.2W, total current: 1.02A, of which PA current: 0.60A, therefore main board current 0.42A
?
?
I haven't found a definitive reference for the safe and optimum values of the RD16HHF1s idle bias current but it seems to range from 200 to 500mA. So I would not recommend long term usage of the 500mA bias I used for these measurements.
I will reset mine to probably the 400-450mA value I read from some articles.
?
3. RD16HHF1s and main board at 12.1VDC, 250mA idle bias each (Total 0.5A PA idle current).?
- At 7.1Mhz:? 10W,? PA current: 1.20A
- At 14.2Mhz: 9W,? ?PA current: 1.21A
- At 21.2Mhz: 4.5W, PA current: 0.65A
- At 28.1Mhz: 5.5W, PA current: 0.95A
?
?
4. RD16HHF1s and main board at 12.1VDC, 500mA idle bias each (Total 1A PA idle current).?
- At 7.1Mhz: 10W, PA current: 1.18A
- At 14.2Mhz: 9W, PA current: 1.26A
- At 21.2Mhz: 5W, PA current: 0.71A
- At 28.1Mhz: 6W, PA current: 1.11A
?
?
5. RD16HHF1s and main board at 13.8VDC, 500mA idle bias each (Total 1A PA idle current).?
- At 7.1Mhz:? 13.5W, PA current: 1.95A
- At 14.2Mhz: 13.5W, PA current: 1.93A
- At 21.2Mhz: 6W,? ? PA current: 1.38A
- At 28.1Mhz: 9.5W,? PA current: 1.79A
?
?
?
Interesting observations:
?
A. The RD16HHF1 produces a much flatter power curver over frequency (in my device), although it shows a dip somewhere near the 15m band.
?
B. The IRF510 can produce some nice power in the lower frequencies when increasing the PA supply voltage, but it comes at the price of a steep power drop at higher frequencies.
?
C. The bias does not seem to influence the efficiency of the finals at full power with RD16HHF1, since biasing at 250 and 500mA produces essentially the same output for the same DC power input. Assuming distortion reduces with higher bias, can we assume a higher bias (within limits) is preferable? Any risk of thermal runaway?
?
D. The board main current (which includes the current in the driving stages of the power amplifier) does not seem to change with frequency from 20m onwards. Is this because the gain is pretty constant? If so, most of the drop in power with increasing frequency seems to be in the IRF510s, supporting the results obtained with the RD16HHF1s.
?
E. With the current uBitx PA circuit the RD16HHF1 seems limited in output, although not having the proper test equipment I can't say where the limitation occurs.
?
F. When I increased the drive through VR1 I noticed that at around 40% for the lower frequencies and at around 60% for the top frequencies I get a compression effect and the output does not increase much more from there on. I left it at 60% and got a positive feedback on the voice quality on my first QSO on 40m. Therefore I assume that the compression/clipping is not significant at that level (but I can't measure the sprectral purity).
?
?
So since my target was around 10W on 10m and 10 to 15W on 40m minimum I can say I have reached my goal just by changing the finals to RD16HHF1s and supplying the board with 13.8VDC (below the 15.2/15V stated in the respective datasheets of the RD16HHF1 and TDA2822).
?
To replace the finals I simply cut the legs of the IRF510s about 3mm above the board and correspondingly cut and crossed over the drain and source pins of the RD16s to match, then soldered in place.
?
It would be interesting to compare these results with others who performed the finals swap on the stock uBitx.
?
Next is the installation of the TPA2016 audio amplifier with I2C controllable AGC.
This is a lot of fun.
?
All the best,
?
73, John (VK2ETA)
?
|
Thanks for that, I thought it might be something as simple as that
cheers and 73
WRS VE7CWS
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Re: uBitx LCD Viewing Angle and Replacement Hints Needed
A little change of contrast potentometer ( JUST 5 DEGREES ON? EITHER SIDE OF PRESENT ) would also help orientation.
?Please on't turn too much.
On Thu, Feb 15, 2018 at 8:39 AM, Mike Lichtman via Groups.Io <tchrme@...> wrote: Good evening. I have my uBitx mounted in a cabinet that working well with 12w on 75m and 9 on 40m. The only problem is
I went to put it on a shelf on my operating desk and the viewing angle made the display unreadable. While not?
a new to electronics, I am new to playing with digital and lcd displays. Can anyone recommend a plug and play blue/white or black/white display
without the viewing angle concerns that is as close to the current opening size as possible? 73 Mike KF6KXG
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Re: Raduino Replacemnt, COMING SOON!
OK
could also use longer header pins on the LCD if socketting the NANO.
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Re: Raduino Replacemnt, COMING SOON!
HI Glen,
That decision is up to the builder... If socketing I imagine I2C LCD is going to be needed and/or remote mounting the LCD.
73
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Re: Raduino Replacemnt, COMING SOON!
sorry, this was meant for Nic not Ian.
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Re: Raduino Replacemnt, COMING SOON!
Ian, did you plan to have the NANO board as a plug in rather than solder in??? If so I think you might have height issues once the LCD is fitted.
glenn
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The one supplied has a 4 mm shaft while the encoder has a 6 mm shaft. I found Mentor Knobs that had the same style for both shaft sizes.? See my photos posted or my QRZ page.
I ordered from Farnell in the UK (export site) and apparently they must ship a container to the US each day and then send by Mail as I paid a almost nothing to get them here in the US.
Dave WI6R
On Wed, Feb 14, 2018 at 4:02 AM, Robert Goodwin <bobgn1@...> wrote: What is the shaft size on the provided audio pot in the uBITx?? It was 0.16 in the BITx40 but pictures of the uBITx parts make me think it might be different in the the uBITx.? I'm trying to get all the parts that I have to provide together before the kit arrives, and this knob is of interest.
Bob, N4HCI
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Charles D. Smith
Raj vu2zap
K9HZ
Nick VK4PP