What is the best option to get 10-15 watts output?

[Don Solberg]

I use my HL2 with two homebrew solid state QRO amplfiiers: 1KW (4)SD2943's, and (2)BLF188XR's.  I have designed the input attenuators in these amplifiers for use with a 10-15 watt transceiver.  I have both an Elecraft KX3 and a K3/10. My goal is to be able to easily switch between the three radios.

I have the HL2 working with the SD2943 amplifier but I am limited to about 350 watts output.  I am measuring about 3.7 watts output from my HL2, but I am not sure of the accuracy of my WaveNode sensor at QRP levels, so it may be closer to 5 watts output.

To get full power out of this amplifier I need 10-15 watts depending on the band.

I am looking at two options for a "little" more output power: using (2) RD15HVF1 MOSFETs, or getting a HardRock 50 amplifier.  The first option would require some surgery on my HL2.  I have a lot of experience with high power MOSFET amplifiers and working with larger SMD devices.  I don't have any experience removing the small SMD's used in the HL2.  Based on what I have read on the forum, the higher power option can be done but there hasn't been much experience with this.

The Hard Rock 50 options gives me way more power than I need, and in fact I would have to be very careful not to overdrive my high power amplifiers, especially the BLF188XR.   This option also makes the automatic band changing a little more complicated because I would have to switch the LPF's on the Hard Rock 50 and on my home brew amplifiers. 

 I have built my own amplifier controller, using an Arduino Mega, and I poll the CAT port on the Elecraft radios to get the band data.  I can do something comparable with PowerSDR for the HL2. The Hard Rock 50 also supports a serial interface that I could use with PowerSDR.

I would appreciate any input from members of this forum who have experience replacing SMD devices on the HL2, and also anyone who has implemented the 15 watt option.

I am currently using my HL2 as a panadapter for my K3, so I will probably purchase another HL2 in the next group buy.  That is the HL2 that I would implement the higher power option in, if I end up going that route.

73,

Don

K9AQ

[Bob A. Booey]

Hi Don,

On my HL2, I have been working on a variation of Takashi K's modifications which allow the HL2 to control an HR-50 via a serial connection.  Personally, I think this is a good option (but may or may not be for you) since the HL2 with the HR-50 yields 50W or so making very reasonably powered TRX.  You could easily set the PA settings of the HL2 to limit the power out to whatever you want/need by band, the ability to do this is in the controller SW (PiHPSDR or PowerSDR in my case).

I think including the HR-50 part of Takashi's code in the current and future gateware would be a wonderful thing but at the current time you have to run Takashi's gateware in order to do this.  Takashi graciously went ahead and made a special gateware release for me which uses the current CW Key jack (which did not exist when he did his original work) for a CW keyer (in gateware) and provides HR-50 serial and PTT control signals on convenient HL2 DB1 pins of the current HL2 design.  These I am routing via MOSFET's to a DB-9 serial connector that will go on the HL2 rear end plate.

So that's my $0.02, for what it is worth.

73,

Robert, WA2T

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[Don Solberg]

Bob,

I have followed what you are doing with this interface.  For the way that I operate, using serial CAT commands from PowerSDR to communicate frequency data to one or more external amplifiers works well.  I have done a lot of CAT command programming with my amplifier controller so I am very comfortable with that.  I know that I can reduce the power output from the HL2 so that the output from the Hard Rock 50 stays below my amplifier drive limits.  I see the other option, increasing the power out of the HL2 as being the best for me.  I don't need more than 10-15 watts, and this would be very comparable to the output from my KX3 and my K3/10.

With all that said, the Hard Rock is a very simple way to get more power, and it is reasonably priced.

Don

K9AQ

[Christopher KB3CS]

would you consider not enabling the on-board PA on the HL2 and instead use the 10W Linear PA from QRP Labs to drive your QRO amplifiers?

  - 1x (base 39) -

On Sunday, August 25, 2019 at 6:19:42 PM UTC-4, Don Solberg wrote:

Bob,

I have followed what you are doing with this interface.  For the way that I operate, using serial CAT commands from PowerSDR to communicate frequency data to one or more external amplifiers works well.  I have done a lot of CAT command programming with my amplifier controller so I am very comfortable with that.  I know that I can reduce the power output from the HL2 so that the output from the Hard Rock 50 stays below my amplifier drive limits.  I see the other option, increasing the power out of the HL2 as being the best for me.  I don't need more than 10-15 watts, and this would be very comparable to the output from my KX3 and my K3/10.

With all that said, the Hard Rock is a very simple way to get more power, and it is reasonably priced.

Don

K9AQ

On Sunday, August 25, 2019 at 4:09:44 PM UTC-5, Don Solberg wrote:

I use my HL2 with two homebrew solid state QRO amplfiiers: 1KW (4)SD2943's, and (2)BLF188XR's.  I have designed the input attenuators in these amplifiers for use with a 10-15 watt transceiver.  I have both an Elecraft KX3 and a K3/10. My goal is to be able to easily switch between the three radios.

[...]

[dick_...@hotmail.com]

TAPR still has Pennywhistle kits  10 - 15 W out but no filters.

Dick K9IVB

[Steve Haynal]

Hi Don,

Your 3.7W seems low. Have you rewound your T3 as described on the wiki page?

You may be able to get a little more power out of the current PA. There are some resistor values you can change if you want to try this.

The PCB is designed to have an experimental "universal" PA. You can mount RD15HVF1 (more expensive) devices to the side of the enclosure, then bend the leads and use your existing PCB. There are some other higher power devices that will fit on the same LDMOS footrpint.

You can just not use the HL2 PA and instead use the low power output with another PA.

73,

Steve

kf7o

[John Williams]

These pages contain some of the research that was performed on the push pull designs for HL2.

https://www.qsl.net/in3otd/ham_radio/Hermes-Lite/Hermes-Lite.html

Discussion

https://groups.google.com/forum/#!searchin/hermes-lite/rd15hvf1%7Csort:date/hermes-lite/mDI7p0eWFys/a4zFoz2pAwAJ

John

W9JSW

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[Christopher KB3CS]

graphs in the "Standalone tests" section of https://www.qsl.net/in3otd/ham_radio/Hermes-Lite/RD15HVF1_PP_PA.html

seem to be missing. filesystem permissions at the server?

same problem in the same section of https://www.qsl.net/in3otd/ham_radio/Hermes-Lite/AFT05MS003N_PP_PA.html

  - 1c (base 61) -

On Monday, August 26, 2019 at 6:50:58 AM UTC-4, John Williams wrote:

These pages contain some of the research that was performed on the push pull designs for HL2.

https://www.qsl.net/in3otd/ham_radio/Hermes-Lite/Hermes-Lite.html

Discussion

https://groups.google.com/forum/#!searchin/hermes-lite/rd15hvf1%7Csort:date/hermes-lite/mDI7p0eWFys/a4zFoz2pAwAJ

John

W9JSW

[...]

[Don Solberg]

Steve,

I sent my HL2 to you for a firmware install and you made the PA improvements at that time. This is what you told me at that time. "I rewound T3 with better wire and shorter leads. I added the 150pF to C84 recommended by Claudio. I will include a 100 Ohm resistor in case you want to change R55, but that probably isn't necessary. (the 100 ohm resistor was not included) I see over 5W on all bands. The bias looks good." 

I suspect that my wattmeter isn't accurate at 5W.  The next time I am up my cabin, where the HL2 is, I will measure the output voltage with my scope and get an accurate measurement.  Even if it is 5 watts, I still need more output power to drive my amplifiers to full power.  

I am leaning toward buying another HL2 and making the "high" power option modifications.  

73,

Don

K9AQ

On Sunday, August 25, 2019 at 4:09:44 PM UTC-5, Don Solberg wrote:

[Steve Haynal]

Hi Group,

If anyone is experimenting with higher output, please also review the max voltage of the capacitors in the PA and the N2ADR filter board. They may need to be increased to handle higher power, especially when there is a mismatch.

73,

Steve

kf7o

[James Ahlstrom]

Hello Group,

Be sure to consider the power handling capability of both the inductors and capacitors on the N2ADR filter board. These are small surface mount parts. I did not test them at greater than 5 watts, and I doubt they will survive 15 watts. Increase the power gradually, and look for heating in the inductors.

Jim

N2ADR