Re: RD16HHF1 power curve flattening...some

Henning Weddig

even with the mods. the TX string shows a 3 dB drop in output power...

Please exchange the two single chokes L8 / L9 with a bifilar wound coil on a e.g. FT43-50 core, see the reasons for that mod in the description already cited in this forum  "".

BTW: how was the output power determined?

How does the power curve PIn - POut look like,

Is the output power measured at the 1 dB compresion point?

Tests on my tries to build a PA with the RD16HFF1´s using different output transformer configurations (even with a 1:4 guanella transformer with 25 ohm coaxial cable on two BN43-202 cores + Balun with 50 ohm coaxial cable on a FT43-80 torroid core + bifilar choke (FT43-50 torroid) + extra choke on the center tap  with a R-C combinaiton to terminate even harmonics) I was not able to get more than 10 W output power at P1dB.  Therefore I am really sceptical about the high power results of > 16 W.

The "hot" cores show that something must be wrong!

Did You measure the suppression of the even harmonics which should be well suppressed  (at least 40 dB) ? How good are the odd harmoncis suppressed?  If the third harmonic is only 10 dB down (1/3 of the amplitude of the fundamental wave) the PA produces square waves, which is not a performance of a linear amp.

IM performance??

Henning Weddig

Am 21.03.2018 um 12:41 schrieb John:

Hello Nik,

How did you go with the feedback issue?

My power amp mods in summary:  finals as RD16HHF1s, feedback resistors R261/R262 as 820 Ohms, Transformer 2T primary / 3T secondary on BN43-202, 180pF across the output transformer primary and 330pf across R87/R88. That's a way.

Heavily inspired by Erhard's (DF3FY) information as displayed on

Results per band at 14V supply, RV1 at %60, RD16's biased at 250mA each:
Band      output power   Total current
80M        22W                         2.9A
40M        20W                         3.2A
30M        16W                         2.3A
20M         16W                        2.7A
17M         15W                        2.4A
15M         12W                        1.6A
12M         12W                    not measured
10M         12W                        1.7A

At 22W the output transformer does get warm but not the LPFs.

Wound back RV1 to get 9-10W on the high frequency bands and 16-18W on the lower ones.

All the best,

73, John (VK2ETA)

FDIM/Dayton hamvention, room to share

David Wilcox

I have a room one block up from the Holiday Inn Fairborn and my usual buddies cannot attend this year. So, I am willing to share and split the cost with one or two other hams who (like me) were too late registering for a room at the Holiday Inn. I do not smoke or snore. I can provide references. In the past I have picked up folks from the Dayton Airport on my way down Wednesday.

Please reply direct to Djwilcox01 AT gmail DOT com

Dave K8WPE
Check out my QRZ bio.

Re: RD16HHF1 in the uBITX #ubitx

K9HZ <bill@...>

Well i just took the signal off the existing relay pins for the band filters because they are big and easy to solder too underneath, but you could easily just connect to the collectors of the relay drive transistors if your eyes are better than mine!

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:

email:  bill@...


On Mar 21, 2018, at 6:57 AM, Bruce Anderson <bwanderson@...> wrote:

Hi Bill,

How did you tap the TXA, TXB, TXC signals?  Before or after the switching transistors?  If after, underneath the relays?  I’m interested not only in this mod (to drive every band at 5W key down), but to band-switch a linear amp, too.  It would be great to keep those signal wire above the board, though. 

Thanks de W1BWA

Re: uBITX Audio Breakout Plus board... #ubitx

Paul Galburt - K2AYZ

The LM324 is a rock solid device and has been around for decades. It is a bit noisy (35 nV/Hz^-2) and has a low slew rate (0.7V/uS). This means that at 8 volts peak audio, it will become slew rate limited at 10KHz. This is all acceptable for speech in a radio. The LM324 can handle much higher supply voltages (32V) than are seen in the uBitx design. About $0.50 each.

The TLC274 is has a higher slew rate (3.6V/uS) and will never slew rate limit. Oddly, it has a lower gain-bandwidth product (0.32 MHz vs 0.7 MHz) and a slightly lower noise (25nV/Hz^-2). But, the maximum power voltage is 16V. It costs about $1.60

My choice would be to use the LM324 all around for modest gain speech frequency audio and DC applications.



Re: Erratic tuning with my new uBitx

Chris Clarke G3SQU

Thanks for that info, Howard.

I had been finding it difficult to use the  "Set Tune Step?" function because it seemed to double up with toggling the 'tuning lock',  with tuning lock seeming to be the primary function when holding down the encoder, rather than "Set Tune Step?".

After much repetition of trying to set the tune step, however, it has now stopped toggling the tune lock when I hold the encoder down.

I do feel there was actually something going wrong with the Tune Step routine in my uBITx. Could the tune lock behaviour be a problem with the 'debounce' code or digital noise? At one point the tune step showed 200Hz on the display but it actually used a step of 10Hz. I managed after some repetitions of trying to alter the Tune Step to get it back to stepping at 200Hz. Could this be an inadvertent application of the hardware encoder lock caused by an earthing issue?

I also have a little bit of a problem getting the Extended Menu after selecting "Setup On?". Sometimes I get the Extended Menu, mostly I don't. I haven't discovered a surefire way of getting the Extended Menu, just seems a matter of luck. Fortunately it's not something I need to return to often.

Also it seems the maximum tuning step is 200Hz. This is not a very useful value - 1MHz would be much more useful to me.  I'm looking at the code to see if and how I could change the values for "tuneStepIndex". Are you able to you advise on this?

Chris G3SQU

Re: PCB Price Comparison tool

Jack, W8TEE

This is the company that has produced all my boards, including those sold by QRP Guys. Perhaps not the cheapest, but great quality and reasonably fast turn around.

Jack, W8TEE

On Wednesday, March 21, 2018, 5:30:09 AM EDT, <ste007ste@...> wrote:

I've used Seeedstudio Fusion PCB manufacture service a few times too. 
Start at only $4.9 but can fab very complicated boards. Excellent quality and service.

Re: ESP8266 or ESP32 Raduino Alternatives?

Michael Monteith

 I have initially loaded the code from Farhan's Github site and got it to compile successfully with a minor tweak.  Minor step I know.  But at least confirmed it can be done.  I just haven't had the time to expand the testing.  Between work and projects around the house I run slow getting some of this stuff done. 

73, Michael

On Tue, Mar 20, 2018 at 06:20 am, Robert Weiman wrote:
I just got my uBitX, and I plan to only do the longevity and reliability fixes before starting to use it.  While reading up on them, I noticed some threads/pages about Raduino replacements involving other Arduino boards for more I/O, etc.  I was wondering if anyone had tried the ESP8266 or ESP32 running the Arduino core as an alternative with more space for expanding into some of the digital protocols?

My Case designed for the uBITX #ubitx

Carl Beck

This is a question for those who have purchased my Case.  (See attached PDF File.)
I received an email this morning saying the Knobs I designed to go with my uBITX Case are loose on the shaft.  On my uBITX that I assembled in January the knobs have a snug fit.  I was wondering if those parts for tuning and volume have changed?  If you have purchased my Case; please give me some feedback so I can modify my Knob design.

Re: Erratic tuning with my new uBitx


Are you using the KD8CEC firmware? That makes a huge difference in many things.   Also, I found it helpful to add a separate push button across the encoder switch.   It's easier to use that way.
Howard K4LXY

Re: Any gotchas replacing the TDA2822 with an LM386? #ubitx #ubitx-help

John McClun

I ordered NJM2073D which is a direct pin for pin replacement for TDA2822 WX but good to 15V.  I'll let you know how it works.


Re: Mechanical work is done...


Howdy Jeff,

As I said, the case was one I had laying around.  Since it had the space I was going to put a 45 w linear amp in and ordered a kit off of Alibaba.  Unfortunately it has nothing but SMDs and I am unable to do that kind of delicate work any more.  Doing the gross kind of soldering required for the uBITX is about all I can handle (getting old really sucks).  I do like your idea of putting in a battery though.  I have a couple of those really small jump start batteries they sell now and one of those would fit in there rather nicely.


On Tue, Mar 20, 2018 at 4:28 PM, <raoul@...> wrote:

Woo Hoo!  Looks really good.  You sure left a lot of space for "stuff" inside the case.  Battery?  Antenna tuner?  Linear amp?  Lots of possibilities!  Keep chipping away at it.



I always thought the Universe was a wonderfully strange place until I studied Particle Physics - I now know the Universe is, in fact, profoundly odd in nature

Re: Any gotchas replacing the TDA2822 with an LM386? #ubitx #ubitx-help

Ben Kuhn

Looks like I should be able to install the socket and build the adapter to get started for now.  It's no big deal to unplug the adapter and plug in a NJM2073D later if that works well.

Re: Any gotchas replacing the TDA2822 with an LM386? #ubitx #ubitx-help

Gary Shriver

Is the NJM2073D a direct drop-in replacement for the TDA2822?  No board mod required.

On Mar 21, 2018, at 7:11 AM, Ben Kuhn <ben.kuhn@...> wrote:

Looks like I should be able to install the socket and build the adapter to get started for now.  It's no big deal to unplug the adapter and plug in a NJM2073D later if that works well.

Re: WSJTX on uBitx

Rod Davis

Hi All,

WSJTX now works with uBITX out of the box.

See ZL1AXG's excellent website for the description; the March 20 entry.


Re: Microphone, simple fix.

John McClun

Denny -

There may not be any stores left but RS is still in the e-com business.  Try this element:


Re: uBITX Audio Breakout Plus board... #ubitx


I like this idea as it reduces the clutter of mod boards inside. How about also adding an effective TX/RX anti-thump/pop circuit too similar to Joe VE1BWV's mod (message#40426).
For me it eliminates all of the TX to RX pop and shortens the initial pop on RX to TX ( on cw keydown). Can't quite get rid of all that key down pop but it's improved.



Re: WSJTX on uBitx


ZL1AXG Website is?


Re: WSJTX on uBitx

Karl Heinz Kremer, K5KHK

It's in the footer of every email you receive from this list: BITX Web Site of Mike ZL1AXG
Karl Heinz - K5KHK

Re: WSJTX on uBitx


Thank you!

Re: Erratic tuning with my new uBitx

Chris Clarke G3SQU

Hi Howard

Yes, I am using the KD8CEC firmware. I did install a separate push button instead of the encoder's one, and for convenience sake I placed it under the volume control (ie LH for  menu , RH for tuning) and it was then I first noticed the problem with jumping into tuning lock. I put a a twisted pair back to where to the yellow earth wire goes to the encoder, so that's quite a long run but I thought I shouldn't use a separate earth point. I'm actually wondering whether to leave the encoder's switch in circuit and take my twisted pair to the push button from it, but at the moment I've removed the leads to the push button.

As a point of interest, I'm using the plastic Excellway® EF01 Electronic Project Case but I'm now thinking of rebuilding into a metal case big enough to provide some modular screening.

Thanks for the reply.

73 Chris

PS I think my biggest issue is going to be RF power out - only 4W on 40m, 2W on 20m.
Looking at replacing the finals.

From: <> on behalf of DrZ <zehrhj2@...>
Sent: 21 March 2018 13:40
Subject: Re: [BITX20] Erratic tuning with my new uBitx
Are you using the KD8CEC firmware? That makes a huge difference in many things.   Also, I found it helpful to add a separate push button across the encoder switch.   It's easier to use that way.
Howard K4LXY