Date   
Re: Weird things happening after upgrading U3S to V3.12

Kelly Keeton
 

Something got bumped in the reflash and your PPS and data lines and ground are not connected properly?

Sent from a mobile device. 

On Feb 5, 2017, at 9:53 AM, Hermann Wagner <dl8mcp@...> wrote:

Hi all,

after running the U3S successfully for over a year, I decided to upgrade from V3.08 to V3.12. So I burned the firmware to the chip, redid all the settings and everything seemed ok.

Except! The second line of the LCD was always empty - no matter what I selected in "GPS Info". The heart beat was always there. After some try-and-error I found out that it worked only when I switched "GPS check" to 0. GPS Module is VK2828U7G5LF. Ok I can live with that. Problem is: The time is never set. I get a 3D fix, coordinates and altitude But the time is never set.
So I let it run, hoping that maybe after the first transmit cycle (WSPR, 30m) it would change. Well it did. Big time!!
So first when it started transmitting, I could see on the SWR meter power going out but I could not hear anything in the control receiver. I am running the tests on a dummy load and until now I could hear a very clear signal in the FT817. I thought the frequency might be way off so I searched everything from 10 to 11MHz. Niente!
But after the transmit cycle was over things started to get really weird.

First there was no calibration.
Then - interestingly enough - the PPS LED on the GPS module went out for a while then it came back on.
The fix was gone although t=14 and s=20 and it did not come back.
On the second row of the LCD the first character in Lat. and Long. were replaced with a symbol similar to the one that shows during calibration.

After a power cycle everything was back and the whole thing started again.
Voltage is constant 5.13V, GPS module is new.

Any ideas what might have gone wrong?

vy 73 de Hermann AJ4ZS

Re: Transmitted signal gone all fuzzy

 

Thought so.

Oh well, maybe there's a first time for everything.

I'm grabbing your grabs here, most useful as always.

73 de Andy

Weird things happening after upgrading U3S to V3.12

Hermann Wagner
 

Hi all,

after running the U3S successfully for over a year, I decided to upgrade from V3.08 to V3.12. So I burned the firmware to the chip, redid all the settings and everything seemed ok.

Except! The second line of the LCD was always empty - no matter what I selected in "GPS Info". The heart beat was always there. After some try-and-error I found out that it worked only when I switched "GPS check" to 0. GPS Module is VK2828U7G5LF. Ok I can live with that. Problem is: The time is never set. I get a 3D fix, coordinates and altitude But the time is never set.
So I let it run, hoping that maybe after the first transmit cycle (WSPR, 30m) it would change. Well it did. Big time!!
So first when it started transmitting, I could see on the SWR meter power going out but I could not hear anything in the control receiver. I am running the tests on a dummy load and until now I could hear a very clear signal in the FT817. I thought the frequency might be way off so I searched everything from 10 to 11MHz. Niente!
But after the transmit cycle was over things started to get really weird.

First there was no calibration.
Then - interestingly enough - the PPS LED on the GPS module went out for a while then it came back on.
The fix was gone although t=14 and s=20 and it did not come back.
On the second row of the LCD the first character in Lat. and Long. were replaced with a symbol similar to the one that shows during calibration.

After a power cycle everything was back and the whole thing started again.
Voltage is constant 5.13V, GPS module is new.

Any ideas what might have gone wrong?

vy 73 de Hermann AJ4ZS

Re: Transmitted signal gone all fuzzy

Keith, G6NHU
 

Windows VM on OS X, yes.

But that’s how I’ve always done it - Every single time I’ve run a grabber before, this is how it’s run and I’ve never seen these symptoms before.

I even rebooted the Mac yesterday, that doesn’t happen very often :-)

73 Keith.


On 5 Feb 2017, at 17:19, punkbiscuit via Groups.Io <punkbiscuit@...> wrote:

>A quick restart of the VM and it’s back to normal.

VM ?

That could be the issue then. Running a VM might be allowing the two O/S's to get it's panties in a twist ?

I'm gonna make a guess and assume your running a Windows VM on IOS.

73 de Andy



Re: Transmitted signal gone all fuzzy

 

>A quick restart of the VM and it’s back to normal.

VM ?

That could be the issue then. Running a VM might be allowing the two O/S's to get it's panties in a twist ?

I'm gonna make a guess and assume your running a Windows VM on IOS.

73 de Andy


Re: Transmitted signal gone all fuzzy

Vernon Matheson
 

Keith that happens here once in a while when the computer is on for extended periods...things go fuzzy...just do a reboot and all ok...have no idea what causes it.

Vern

Sent from my BlackBerry 10 smartphone on the Rogers network.
From: Keith Maton
Sent: Sunday, February 5, 2017 3:47 AM
To: QRPLabs@groups.io
Reply To: QRPLabs@groups.io
Subject: Re: [QRPLabs] Transmitted signal gone all fuzzy

Lock is absolutely fine, DC is coming from a PSU that’s more than capable (main shack PSU, running at barely tickover).

No physical damage to the unit, it’s been sitting in exactly the same place for well, years!

All I did was move it from 20m to 40m by enabling some of the frequency slots and disabling others.

73 Keith.


On 5 Feb 2017, at 07:20, Kelly Keeton via Groups.Io <kellykeeton@...> wrote:

yea I dont think it is either.. hows your clock temperature stability look, what about your DC/feed power stability?

did the unit get any damage or shock lately that could be causing cold solder issues?


On Saturday, February 4, 2017 11:17 PM, Keith Maton <nentecular@...> wrote:


Barely ticking over.  If I switch the transmitter off and back on again, it’s OK.  I don’t think it’s anything to do with the grabbing computer.


On 4 Feb 2017, at 22:58, mikael_dagman@... wrote:

Hi, I get similar problem when I put to much load on the computer to process, when this happens what does your grabbing computers CPU load looks like?





Re: Transmitted signal gone all fuzzy

Keith, G6NHU
 

Well this is getting more curious.

I’ve just noticed my grabber, which has been running perfectly since last night suddenly looked like this.



A quick restart of the VM and it’s back to normal.


So perhaps it was the grabber playing silly bollocks after all but I don’t quite understand how or why it would do that.

I’m going to put the transmitter back on and keep an eye on it via WSPR - If I get WSPR decodes then it’s working.

73 Keith.





On 5 Feb 2017, at 08:06, Alan via Groups.Io <alan4alan@...> wrote:

On 04/02/2017 22:02, Keith Maton wrote:

My U3S has been running continually for many months with only the odd
break.  Today I switched over to 40m and started my own grabber so I
could keep an eye on my signal.
> After a short while, I noticed that the transmitted signals were looking
odd, a bit fuzzy so I restarted my transmitter and all was clean again.


Keith

Assuming it is not the RX then I'd first look at the signal from the reference crystal.

Although as if it happened after changing frequency how about RF getting in?

73 Alan G4ZFQ





More Sources for RD15HVF1

J68HZ
 

Looks like thepartsplace has them too…

 

http://thepartsplace.k5nwa.com/index.php?route=product/product&product_id=63

 

 

 

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

 

 

email:  bill@...

 

Re: U3S output fets

J68HZ
 

Sorry that was not correct.  Mouser and Digikey don’t carry them anymore.  But RFParts does:  https://www.rfparts.com/rftransistors/transistor-rd/rd15hvf1.html

 

 

 

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

 

 

email:  bill@...

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of K9HZ
Sent: Sunday, February 05, 2017 9:24 AM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] U3S output fets

 

Both Mouser and Digikey have them. 

 

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 Feb 5, 2017, at 8:35 AM, Emory Haines <wm3m73@...> wrote:

Considering substituting the RD15HV1 in my 5 watt PA kit.  I have done many searchers looking for one.  Only place I find who even has them is on Ebay from China?  Shipping takes weeks and do not want to wait that long.  Anyone know of a quicker source?  I checked Mouser, DigiKey, etc, they do not carry it?

Thank you  73

Emory  WM3M

 

On 2/4/2017 11:56 AM, K9HZ wrote:

The U3A by itself doesn’t have enough drive to make more than 500 mw output from the RD15HVF1 … BUT if you drive the RD15HVF1 with one BS170 on the U3A (at about 150 mw), it should make at least 12 watts…  I home brewed one (before Hans put out his kit) and mine certainly will put out that much power and more depending on the power source voltage.  The nice thing about using the RD15HVF1 is that it puts out a good amount of power above 20 mhz… well into the 200 MHz range… whereas the IRF510 (depending upon the quality of the device in manufacturing) quits at about 20 mhz.   But if you stay below 10 MHz, the IRF510 part is cheaper and will work fine.

 

You only need to use ONE part in any event!!!!! 

 

 

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! <image001.gif>

 

 

email:  bill@...

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ian liston-smith
Sent: Saturday, February 04, 2017 9:58 AM
To: QRPLabs@groups.io
Subject: [QRPLabs] U3S output fets

 

Has anyone had any success getting about 500mW (on 40) on a U3S with a 12V supply from one (or two) RD15HVF1 devices?

 

I have a U3S running three BS170 fets with a PA voltage of 12V. The bias set so that without drive, total U3S current was about 50mA, and R5 adjusted until it rose to about 53mA.

Maybe my R5 has a bad bit of track, but occasionally the output falls to less than 100 mW, but sometimes rises to over 1 W by itself and the fets (glued to a heat sink) get very hot!

When it's prone to these variations the power fluctuates by about 6dB intermittently, but the drops to the much lower level. I've also observed this on a scope at the fets drains. I've checked for dry joints and swapped the LPFs to no effect.

I suspect it's probably one of the fets misbehaving rather than R5 (although this doesn't really explain the power increase), and it seems heat related. Strangely, on 80m, for the past few days the power has remained fairly stable at about 200 to 250mW - though does vary a little. (Just doing another test on WSPR on 40m - to see what happens.)

Anyway, are one, two or even three RD15HVF1 (used in Hans's 5W PA) worth trying here on the U3S? Or even a couple of VN10 fets?

Thanks.

 

Ian, G4JQT

 

Re: U3S output fets

J68HZ
 

Both Mouser and Digikey have them. 


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 Feb 5, 2017, at 8:35 AM, Emory Haines <wm3m73@...> wrote:

Considering substituting the RD15HV1 in my 5 watt PA kit.  I have done many searchers looking for one.  Only place I find who even has them is on Ebay from China?  Shipping takes weeks and do not want to wait that long.  Anyone know of a quicker source?  I checked Mouser, DigiKey, etc, they do not carry it?

Thank you  73

Emory  WM3M


On 2/4/2017 11:56 AM, K9HZ wrote:

The U3A by itself doesn’t have enough drive to make more than 500 mw output from the RD15HVF1 … BUT if you drive the RD15HVF1 with one BS170 on the U3A (at about 150 mw), it should make at least 12 watts…  I home brewed one (before Hans put out his kit) and mine certainly will put out that much power and more depending on the power source voltage.  The nice thing about using the RD15HVF1 is that it puts out a good amount of power above 20 mhz… well into the 200 MHz range… whereas the IRF510 (depending upon the quality of the device in manufacturing) quits at about 20 mhz.   But if you stay below 10 MHz, the IRF510 part is cheaper and will work fine.

 

You only need to use ONE part in any event!!!!! 

 

 

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! <image001.gif>

 

 

email:  bill@...

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ian liston-smith
Sent: Saturday, February 04, 2017 9:58 AM
To: QRPLabs@groups.io
Subject: [QRPLabs] U3S output fets

 

Has anyone had any success getting about 500mW (on 40) on a U3S with a 12V supply from one (or two) RD15HVF1 devices?

 

I have a U3S running three BS170 fets with a PA voltage of 12V. The bias set so that without drive, total U3S current was about 50mA, and R5 adjusted until it rose to about 53mA.

Maybe my R5 has a bad bit of track, but occasionally the output falls to less than 100 mW, but sometimes rises to over 1 W by itself and the fets (glued to a heat sink) get very hot!

When it's prone to these variations the power fluctuates by about 6dB intermittently, but the drops to the much lower level. I've also observed this on a scope at the fets drains. I've checked for dry joints and swapped the LPFs to no effect.

I suspect it's probably one of the fets misbehaving rather than R5 (although this doesn't really explain the power increase), and it seems heat related. Strangely, on 80m, for the past few days the power has remained fairly stable at about 200 to 250mW - though does vary a little. (Just doing another test on WSPR on 40m - to see what happens.)

Anyway, are one, two or even three RD15HVF1 (used in Hans's 5W PA) worth trying here on the U3S? Or even a couple of VN10 fets?

Thanks.

 

Ian, G4JQT


Re: U3S output fets

Emory Haines <wm3m73@...>
 

Considering substituting the RD15HV1 in my 5 watt PA kit.  I have done many searchers looking for one.  Only place I find who even has them is on Ebay from China?  Shipping takes weeks and do not want to wait that long.  Anyone know of a quicker source?  I checked Mouser, DigiKey, etc, they do not carry it?

Thank you  73

Emory  WM3M


On 2/4/2017 11:56 AM, K9HZ wrote:

The U3A by itself doesn’t have enough drive to make more than 500 mw output from the RD15HVF1 … BUT if you drive the RD15HVF1 with one BS170 on the U3A (at about 150 mw), it should make at least 12 watts…  I home brewed one (before Hans put out his kit) and mine certainly will put out that much power and more depending on the power source voltage.  The nice thing about using the RD15HVF1 is that it puts out a good amount of power above 20 mhz… well into the 200 MHz range… whereas the IRF510 (depending upon the quality of the device in manufacturing) quits at about 20 mhz.   But if you stay below 10 MHz, the IRF510 part is cheaper and will work fine.

 

You only need to use ONE part in any event!!!!! 

 

 

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

 

 

email:  bill@...

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ian liston-smith
Sent: Saturday, February 04, 2017 9:58 AM
To: QRPLabs@groups.io
Subject: [QRPLabs] U3S output fets

 

Has anyone had any success getting about 500mW (on 40) on a U3S with a 12V supply from one (or two) RD15HVF1 devices?

 

I have a U3S running three BS170 fets with a PA voltage of 12V. The bias set so that without drive, total U3S current was about 50mA, and R5 adjusted until it rose to about 53mA.

Maybe my R5 has a bad bit of track, but occasionally the output falls to less than 100 mW, but sometimes rises to over 1 W by itself and the fets (glued to a heat sink) get very hot!

When it's prone to these variations the power fluctuates by about 6dB intermittently, but the drops to the much lower level. I've also observed this on a scope at the fets drains. I've checked for dry joints and swapped the LPFs to no effect.

I suspect it's probably one of the fets misbehaving rather than R5 (although this doesn't really explain the power increase), and it seems heat related. Strangely, on 80m, for the past few days the power has remained fairly stable at about 200 to 250mW - though does vary a little. (Just doing another test on WSPR on 40m - to see what happens.)

Anyway, are one, two or even three RD15HVF1 (used in Hans's 5W PA) worth trying here on the U3S? Or even a couple of VN10 fets?

Thanks.

 

Ian, G4JQT


Re: WSPR - ROCKS!

Alan
 

On 04/02/2017 14:42, Alan Adamson wrote:
As some know, I've had 2 long duration, high altitude balloons up
since August of last year.
Alan,

Thanks for the info. I have a 20m WSPR RX and was interested to find a few spots from your balloon.
I copy below from a different post of yours that answers some listener's questions and the spots I made yesterday.
I guess I'd just thought those and K4MEA were just stations that had mis-configured WSPR.

73 Alan G4ZFQ

=============
2 February at 14:09

For those that have followed my balloons (and again thanks for the
listeners, it couldn't have happened without you!). Looks like while
HIRFW-3 is in the gulf of mexico (it was there yesterday), it didn't
startup up this morning. But HIRFW-6 is close behind it and just showed
up. Transmitting on 20 meter WSPR (14.0956mhz), 2 spots every 10 mins.
Remember the first will be basically a normal spot, but the DBM will be
the altitude in 1000's of meters, the second, will use my telemetry
protocol. It will be located at the correct gridsquare, where the
balloon is, but all of the rest of the values will be different. The
telemetry callsign will be a "Qxxxxx" type callsign as has been
referenced. The main callsign for HIRFW-6 is K4JCW if you want to try to
hear it. It's at about 45000' and is transmitting 10mW of signal into a
vertical dipole. Have fun, it should cross my Longitude today, finishing
it's 10th and starting it's 11th circumnavigation having traveled over
400000km

2017-02-04 18:48:00 14.097102 G4ZFQ IO90ir QT2BLK GL95 4385
100.000 -18 balloon telem
2017-02-04 17:08:00 14.097101 G4ZFQ IO90ir QT2KNK GL85 4514
100.000 -20 balloon telem
2017-02-04 13:48:00 14.097102 G4ZFQ IO90ir QT2DTG GL75 4645
100.000 -23 balloon telem
2017-02-04 12:38:00 14.097103 G4ZFQ IO90ir QT2PXN GL65 4778
100.000 -24 balloon telem

2017-02-04 11:46 K4JCW 14.097103 -23 0 GL66 +43 19.953
G4ZFQ IO90ir 4695 2917
2017-02-04 11:26 K4JCW 14.097103 -24 1 GL66 +43 19.953
G4ZFQ IO90ir 4695 2917

Re: Transmitted signal gone all fuzzy

Alan
 

On 04/02/2017 22:02, Keith Maton wrote:

My U3S has been running continually for many months with only the odd
break. Today I switched over to 40m and started my own grabber so I
could keep an eye on my signal.
After a short while, I noticed that the transmitted signals were looking
odd, a bit fuzzy so I restarted my transmitter and all was clean again.
Keith

Assuming it is not the RX then I'd first look at the signal from the reference crystal.

Although as if it happened after changing frequency how about RF getting in?

73 Alan G4ZFQ

Re: Transmitted signal gone all fuzzy

Keith, G6NHU
 

Lock is absolutely fine, DC is coming from a PSU that’s more than capable (main shack PSU, running at barely tickover).

No physical damage to the unit, it’s been sitting in exactly the same place for well, years!

All I did was move it from 20m to 40m by enabling some of the frequency slots and disabling others.

73 Keith.


On 5 Feb 2017, at 07:20, Kelly Keeton via Groups.Io <kellykeeton@...> wrote:

yea I dont think it is either.. hows your clock temperature stability look, what about your DC/feed power stability?

did the unit get any damage or shock lately that could be causing cold solder issues?


On Saturday, February 4, 2017 11:17 PM, Keith Maton <nentecular@...> wrote:


Barely ticking over.  If I switch the transmitter off and back on again, it’s OK.  I don’t think it’s anything to do with the grabbing computer.


On 4 Feb 2017, at 22:58, mikael_dagman@... wrote:

Hi, I get similar problem when I put to much load on the computer to process, when this happens what does your grabbing computers CPU load looks like?




Re: Transmitted signal gone all fuzzy

Kelly Keeton
 

yea I dont think it is either.. hows your clock temperature stability look, what about your DC/feed power stability?

did the unit get any damage or shock lately that could be causing cold solder issues?


On Saturday, February 4, 2017 11:17 PM, Keith Maton <nentecular@...> wrote:


Barely ticking over.  If I switch the transmitter off and back on again, it’s OK.  I don’t think it’s anything to do with the grabbing computer.


On 4 Feb 2017, at 22:58, mikael_dagman@... wrote:

Hi, I get similar problem when I put to much load on the computer to process, when this happens what does your grabbing computers CPU load looks like?



Re: Transmitted signal gone all fuzzy

Keith, G6NHU
 

Barely ticking over.  If I switch the transmitter off and back on again, it’s OK.  I don’t think it’s anything to do with the grabbing computer.


On 4 Feb 2017, at 22:58, mikael_dagman@... wrote:

Hi, I get similar problem when I put to much load on the computer to process, when this happens what does your grabbing computers CPU load looks like?

Re: Transmitted signal gone all fuzzy

Mikael Dagman
 

Hi, I get similar problem when I put to much load on the computer to process, when this happens what does your grabbing computers CPU load looks like?

Transmitted signal gone all fuzzy

Keith, G6NHU
 

All,

My U3S has been running continually for many months with only the odd break.  Today I switched over to 40m and started my own grabber so I could keep an eye on my signal.  

After a short while, I noticed that the transmitted signals were looking odd, a bit fuzzy so I restarted my transmitter and all was clean again.

A quick glance just now showed me the same symptoms.   Image attached where you can clearly see my FSKCW has gone fuzzy and then my WSPR frame at the top of the screen has gone the same way.

Does anyone have any suggestions as to what could be causing this?

73 Keith G6NHU


Re: Vfo

Hans Summers
 

Hi Ross

Yes, I do want to add new features like that to the VFO. I have had many projects on, and not got to it yet. 

One thing that holds me back, is that I am not sure quite how these additional functions should behave. We have at hand one rotary encoder with a push button on its shaft, and one left button. RIT I can implement with an unused I/O pin to tell the VFO when it is in Rx or Tx mode. That is Ok. The S-meter is Ok too, actually I was working on an S-meter implementation in the VFO a couple of weeks ago. 

As for VFO A/B - I am not sure how this should operate. Maybe we need to discuss it! If you have a clear idea of how it should work, please could you contact me off list? Then maybe I can get this done in the near future. 

73 Hans G0UPL

On Sat, Feb 4, 2017 at 5:25 PM, <bellrossjr@...> wrote:

Hi Hans:

I was wondering if you were going to add any new features to the VFO, maybe RIT, dual vfos, s-meter I have been using the vfo with the Bitx40 been working great. 

Thanks and 73 Ross Bell K7RSB



Re: U3S output fets

J68HZ
 

The U3A by itself doesn’t have enough drive to make more than 500 mw output from the RD15HVF1 … BUT if you drive the RD15HVF1 with one BS170 on the U3A (at about 150 mw), it should make at least 12 watts…  I home brewed one (before Hans put out his kit) and mine certainly will put out that much power and more depending on the power source voltage.  The nice thing about using the RD15HVF1 is that it puts out a good amount of power above 20 mhz… well into the 200 MHz range… whereas the IRF510 (depending upon the quality of the device in manufacturing) quits at about 20 mhz.   But if you stay below 10 MHz, the IRF510 part is cheaper and will work fine.

 

You only need to use ONE part in any event!!!!! 

 

 

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

 

 

email:  bill@...

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ian liston-smith
Sent: Saturday, February 04, 2017 9:58 AM
To: QRPLabs@groups.io
Subject: [QRPLabs] U3S output fets

 

Has anyone had any success getting about 500mW (on 40) on a U3S with a 12V supply from one (or two) RD15HVF1 devices?

 

I have a U3S running three BS170 fets with a PA voltage of 12V. The bias set so that without drive, total U3S current was about 50mA, and R5 adjusted until it rose to about 53mA.

Maybe my R5 has a bad bit of track, but occasionally the output falls to less than 100 mW, but sometimes rises to over 1 W by itself and the fets (glued to a heat sink) get very hot!

When it's prone to these variations the power fluctuates by about 6dB intermittently, but the drops to the much lower level. I've also observed this on a scope at the fets drains. I've checked for dry joints and swapped the LPFs to no effect.

I suspect it's probably one of the fets misbehaving rather than R5 (although this doesn't really explain the power increase), and it seems heat related. Strangely, on 80m, for the past few days the power has remained fairly stable at about 200 to 250mW - though does vary a little. (Just doing another test on WSPR on 40m - to see what happens.)

Anyway, are one, two or even three RD15HVF1 (used in Hans's 5W PA) worth trying here on the U3S? Or even a couple of VN10 fets?

Thanks.

 

Ian, G4JQT