Date   
Re: RD16HHF1 in the uBITX #ubitx

John Backo
 

I think Jerry has a much simpler idea -- just
find a way to disconnect the gate bias during receive.
This would put the gates at 0v, and effectively shut off
the IRF510 drains. Probably a good idea.

It might work, but I wonder about the sudden increase and decrease
of voltage on the gates. it might precipitate oscillation or action in the
non-linear area of operation. The linear area we are using is quite
narrow and a bit unstable.

Probably it would work fine for most, but not so good for a few. It depends on the
actual device in use.

john
AD5YE

Re: RD16HHF1 in the uBITX #ubitx

Jerry Gaffke
 

I believe it has already been done for you.
The LM78L05 regulator that supplies 5v to the IRF510 gate bias pots is in turn powered form the TX 12v rail.
That TX rail is shut down during receive by the TR relay, goes to zero volts, so gate bias will also do so.


On Thu, Feb 15, 2018 at 04:53 pm, John Backo wrote:
I think Jerry has a much simpler idea -- just
find a way to disconnect the gate bias during receive.

Re: RD16HHF1 in the uBITX #ubitx

Arv Evans
 

Jerry

But that does not remove DC from the finals.  I did not notice that the bias was dumped during receive.  That is my error.  

Arv
_-_




Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------
From: "Jerry Gaffke via Groups.Io" <jgaffke@...>
Date: 2/15/18 5:16 PM (GMT-07:00)
To: BITX20@groups.io
Subject: Re: [BITX20] RD16HHF1 in the uBITX #ubitx

In the case of the uBitx and Bitx40 we use the IRF510 FET's to turn off
the PA power by shutting down the gate bias voltage source during receive.
Drain current should be zero.

On Thu, Feb 15, 2018 at 02:43 pm, Arv Evans wrote:
For power conservation it is possible to use a power FET to turn OFF voltage
to the RF PA section during receive mode.  Turn the switch device on with
+TX power and off when this goes to ground.  I used an IRF510 because
I have some spares.
 

Re: RD16HHF1 in the uBITX #ubitx

Jerry Gaffke
 

Indeed, there is the PA+ supply voltage on the IRF510 drains during receive.
But zero drain current because the IRF510 gate voltage is zero
and nowhere else for the PA+ supply to go.  Not so much as a bias or feedback resistor.

So those IRF510 FET's are already doing the job of the extra FET that you had proposed.

Jerry


On Thu, Feb 15, 2018 at 05:40 pm, Arv Evans wrote:
But that does not remove DC from the finals.  I did not notice that the bias was dumped during receive.  That is my error.  
 

Re: RD16HHF1 in the uBITX #ubitx

John Backo
 

The same would be true for the RD16Hxxx devices, incidentally.

john
AD5YE

BITX QSO Afternoon/Night, Sunday, February 18, 3PM/7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere

John P
 

BITX QSO Afternoon/Evening, Sunday, February 18, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Join us as we make contacts from BITX40 to BITX40 on 7.277 MHz in 40 meters!

This is a worldwide event for BITX40 stations starting at 7pm in each time zone. To participate, call CQ BITX on Sunday, starting at 3PM and/or 7PM your local time. The BITX QSO Night continues through the evening and conditions usually improve after sunset, so it is worthwhile to participate later in the evening.

Suggested Best Operating Practices:

Work at QRP power levels unless conditions require more power.
Call and listen for CQ BITX on the hour and every quarter hour.
It is helpful if you call CQ BITX with your callsign, name and location. 
Repeat your callsign a number of times during your CQ BITX and during QSO's.
Start a QSO by confirming the callsign, location, name and signal report of the other operator.
Say the callsign, name and location of the other operator so others can hear.
If the frequency is busy, avoid long conversations.
After your initial QSO is complete, ask if there are any other stations who would like to contact.

Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread.

This is an undirected, scheduled event.  The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls on Sunday evening.  Talk to you then!
--
John - WA2FZW

Re: BITX QSO Afternoon/Night, Sunday, February 18, 3PM/7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere

K9HZ <bill@...>
 

>> “This is a worldwide event for BITX40 stations starting at 7pm in each time zone. To participate, call CQ BITX on Sunday, starting at 3PM and/or 7PM your local time”

 

So this goes on for more than 28 hours then?

 

 

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 John P
Sent: Thursday, February 15, 2018 9:09 PM
To: BITX20@groups.io
Subject: [BITX20] BITX QSO Afternoon/Night, Sunday, February 18, 3PM/7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

BITX QSO Afternoon/Evening, Sunday, February 18, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Join us as we make contacts from BITX40 to BITX40 on 7.277 MHz in 40 meters!

This is a worldwide event for BITX40 stations starting at 7pm in each time zone. To participate, call CQ BITX on Sunday, starting at 3PM and/or 7PM your local time. The BITX QSO Night continues through the evening and conditions usually improve after sunset, so it is worthwhile to participate later in the evening.

Suggested Best Operating Practices:

Work at QRP power levels unless conditions require more power.
Call and listen for CQ BITX on the hour and every quarter hour.
It is helpful if you call CQ BITX with your callsign, name and location. 
Repeat your callsign a number of times during your CQ BITX and during QSO's.
Start a QSO by confirming the callsign, location, name and signal report of the other operator.
Say the callsign, name and location of the other operator so others can hear.
If the frequency is busy, avoid long conversations.
After your initial QSO is complete, ask if there are any other stations who would like to contact.

Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread.

This is an undirected, scheduled event.  The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls on Sunday evening.  Talk to you then!
--
John - WA2FZW


Virus-free. www.avg.com

Re: RD16HHF1 in the uBITX #ubitx

MVS Sarma
 

Rlacement of MOSfets alone can't not solve the case.

 However there is reasonable improvement,. Interestingly, there is a dip in gain at 21.2MHz and recovered at 28 MHz. Twe need to analyse this behaviour. I wonder what would happen if we can tweak C261 and C262  by lowering their values , say 68nF instead of 100nF !!  ??
If R97 and R98 could be increased to say 100 ohms, the gate loading would reduce, I agree that, we  need to ensure thast amplifier would not become unstable.

regards
 sarma
 vu3zmv

 

Re: uBitx LCD Viewing Angle and Replacement Hints Needed

Mike Lichtman
 

Thank you to those who responded to my question. Bill Richardson’s informing me of the contrast control on the back of the
VFO module did the trick. It was originally set to maximum. Now that the green display is toned down and functional, i will probably
stay with it. Maybe in the future I will consider the blue/white or black /white displays. 73 Mike KF6KXG

Re: RD16HHF1 in the uBITX #ubitx

M Garza <mgarza896@...>
 

John,
Have you tried putting a 150 to 330pf cap across pins 1 & 6 on T11?  It might help balance the output.  Most push-pull amps have this cap.

Just a suggestion.

Marco - KG5PRT 

On Feb 15, 2018 7:39 AM, "John" <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)
 



Re: RD16HHF1 in the uBITX #ubitx

John <passionfruit88@...>
 

Hello Marco,

Yes  I saw this cap on some schematics and they are supposed to flatten the gain curve.

Thanks for the suggestion.

I will have a look at this when I am finished with the audio side.

73, John (VK2ETA)

BITX40- tune button- no output

Steve
 

Hi gang.  I've got my '40 assembled, tested, and mounted in a box.  Loaded Allard's latest as well as all his hardware mods, with the exception of the TX-RX mod.  6W output on SSB, but no output on CW when I push the tune button.  I get the sidetone on the speaker, but no movement on the wattmeter.  Something in the Settings Menu?  Any ideas?  I've searched the messages, but no joy.  Thanks, Aloha, Steve WH6ST

BITX40: Allard's Firmware with Rotary Encoder?

Ryan Flowers
 

Hello All,

I got Allard's Raduino sketch to compile on an Uno R3 that I'm playing with, and I also got a rotary encoder working on a test sketch, and now I need to figure out how to make Allard's sketch use the rotary encoder. I'm pretty new to Arduino (this is my first actual project aside from Blink and a few basic tests). I've figured out how to convert to an I2C display- that's easy enough, and I have a version of the sketch that does that successfully. I must be humble and admit that I don't have the time I wish I did, and I'd be better off if someone already figured out the encoder part so I could get a jump on that. I have other mods that I want to do, but Allard's code is so well featured I'd like to start there, if possible.

Thanks for the assist and 73!
--
Ryan Flowers - W7RLF
MiscDotGeek.com
Multi Band BITX40
The BITX40 FAQ

Re: BITX40- tune button- no output

Mike Woods
 

Tune button?   There is no tune button with Allard’s mods!  Maybe you are thinking of the CW spot / fine tune button?  This puts a tone on cw for allowing you to align the incoming signal with the CW offset and it also enables fine tune on the dial with 1 Hz steps.  Holding it down at the same time as the function button will lock the tune dial.

Parallel up a button with the straight key down and this will give you a momentary Tune button.

73 Mike ZL1AXG


On Fri, 16 Feb 2018 at 8:36 PM, Steve Thatcher <stevep2p@...> wrote:
Hi gang.  I've got my '40 assembled, tested, and mounted in a box.  Loaded Allard's latest as well as all his hardware mods, with the exception of the TX-RX mod.  6W output on SSB, but no output on CW when I push the tune button.  I get the sidetone on the speaker, but no movement on the wattmeter.  Something in the Settings Menu?  Any ideas?  I've searched the messages, but no joy.  Thanks, Aloha, Steve WH6ST

Re: BITX40- tune button- no output

Steve
 

Thanks Mike, but according to this

CONNECTING A STRAIGHT MORSE KEY or 'TUNE' BUTTON:

A straight key (or external electronic keyer) can be connected to Raduino pin A1 (connector P1, brown wire). It is recommended to install a 1K series resistor to protect the Arduino input. When the key is up (open) pin A1 will be HIGH. When the key is down (closed, shorted to ground) pin A1 will be LOW, and a carrier will be transmitted.

You could also wire up a simple push button instead of connecting a morse key. The generated CW carrier can be used for tuning up your antenna. In that case please note that you will be transmitting a carrier at full duty cycle, therefore don't keep the tune button pressed for too long to prevent overheating the final!

Am I misunderstanding something here?  Aloha, Steve

Re: BITX40- tune button- no output

Allard PE1NWL
 

Steve, you need to install the TX-RX mod so that the radio will go into TX when you press the button.



Alternatively, you can press PTT manually on the mic and then press the tune button.

73 Allard PE1NWL

Re: top band ubitx

bill richardson
 

Some more info and pictures for anyone wanting to use the uBitx on 160m. 

I’m having a blast on 160m I did add larger heat sinks and a pair of small fans that I can turn on and off as needed to keep the finals cool if I’m long winded or using digital modes.

Qrp labs makes a great low pass filter kit:

On Feb 7, 2018, at 7:22 AM, bill richardson <ng1p.bill@...> wrote:

160m doublet feed with 450 ohm line.
On Feb 6, 2018, at 9:23 PM, Vince Vielhaber <vev@...> wrote:

What are you using for an antenna?

Vince.


On 02/06/2018 08:06 PM, bill richardson wrote:
Turned the output down to about 8 Watts and have made 4 contacts on 160 with great reports. Will add a larger heat sink to be safe.
On Feb 6, 2018, at 7:26 PM, bill richardson <ng1p.bill@...> wrote:

I don’t have a spectrum analyzer but I think your right. Without the LPF installed I’m seeing over 20 Watts out on 160m and with it I see 12watts out so a lot of signal outside of the 160m band is happening...
On Feb 6, 2018, at 7:12 PM, John Backo <jabac@...> wrote:

Bill:

I think what you are seeing is the "normal" variation in the
output of the MOSFETS. Some are better than others at RF.

Gordon's suggestion to turn back the drive is probably the right answer.
Alternatively, you could turn down the gate voltage a bit, but that
would probably introduce compression distortion. Or you could increase
the size of the heat-sink and see how it goes. Probably the wisest thing
to do is both turn back the drive a bit and increase the heat-sink.

Some, but not all, IRF510's are capable of 20W or more on 80m.
you might happen to have some good ones. The key lies in the
harmonic generation and the heat-sinking.

Note that what you are seeing MAY be from UHF oscillation included in
the signal. Be very aware of that. Check your output very carefully.

john
AD5YE









--
Michigan VHF Corp.   http://www.nobucks.net/   http://www.CDupe.com/
                        http://www.metalworkingfun.com






Re: Smoking Genie

Michael Davis <maddmd818@...>
 

I have just finished chasing the smoking R141. Even after replacing the smd with an axial 1/2 watt, mounted vertically, it continued to get blazing hot after only 2-3 seconds of PTT. Be sure to check to see if it's still getting hot. After checking the obvious, rechecking all resistor values, double checking transistor voltages using Randy's chart. After replacing Q14, I still had the problem. I removed R14 again and mounted a new one, elevated like a 3 legged bug. Problem solved. My conclusion, with Q14 mounted tight to the board, there is a risk that the metal Q14 case will short to the board. An insulated spacer should be used or have been used, to keep this device up just a bit from the board. A friend suggested cutting the bottom of my case to access to the entire underside of the board. A great idea for new builders. BTW, I mounted the axial 10 ohm resistor through the tiny hole near it's original location. That connects to the bottom board foil ground, and one of my smd pads were destroyed from unsoldering the burned R141. 

Sent from Mike's iPad WA1MAD

 

Re: uBITX AGC - Adafruit TPA2016, A Success! #ubitx

Fred Buecker
 

The other board was a VK3YE that he said did not work very well.

-Fred
KC3HMS

On Feb 5, 2018 9:47 AM, "Michael Monteith via Groups.Io" <michael_r_monteith=yahoo.com@groups.io> wrote:
Which 2 boards?  I know the one is the TAP2016.  What's the other?

73, Michael
KM4OLT
On Fri, Feb 2, 2018 at 06:13 pm, Nick VK4PLN wrote:
Hi john, both boards from eBay...
I am really happy with the setup, AGC is performing very well in my opinion...

Re: Advice on selling Bitx40 on EBay

Bob Dritz <LANSWITCH@...>
 

Thanks for the responses so far, but what I REALLY want to know is if $100 is too high or too low to expect for all this stuff?