Date   
Re: Variable power control

Jerry Gaffke
 

Here's an old thread well worth reading that touches on pin diode attenuators, mostly in regard to agc for the receiver.
    https://groups.io/g/BITX20/topic/5945215
Here's another old thread:
    https://groups.io/g/BITX20/topic/5913954

Jerry, KE7ER


On Thu, Feb 22, 2018 at 06:34 am, Karl Heinz Kremer, K5KHK wrote:
There is an HP application note about PIN diode attenuators: http://www.hp.woodshot.com/hprfhelp/4_downld/lit/diodelit/an1048.pdf

I was just about to recommend a PIN diode attenuator as well. The device used in this particular configuration reached it's end of life, and may be hard to get soon. There are alternatives: 

https://www.nxp.com/docs/en/data-sheet/BAP70Q.pdf

The data sheet has a chart that shows insertion loss based on frequency and control voltage. 
--

Re: #ubitx Calibration resolution #ubitx

 

Hi Gerald,

I just downloaded and installed V 1.03 from here: https://github.com/phdlee/ubitx/tree/version1.03
Works great.

Joel
N6ALT

uBITX without Raduino

Lawrence Macionski <am_fm_radio@...>
 

A while back you could order a BITX40 without the Raduino.
I checked the www.hfsigs.com web site to see if I can order a uBITX without Raduino.

Not only is there no information in that regard, but there is no way to inquire as to how to obtain one...
Anyone have contact information. To obtain an answer and complete my purchase as needed.

ADVISE

Larry W8LM

Re: More pins for the Raduino! An RF gain control for the uBITX!

al_91dak@...
 

While we're at it, why not 40x 2k 1/4W?

IF AGC #ubitx

Roberto Vannucci
 

I'm building  uBitx  I intend to furnish it with IF AGC, for this I built a 12 Mhz amplifier and related circuit to drive an S Meter and get the driving voltage for pin 2 of the integrated MC1590G according to the ARRL HANDBOOK 1989 scheme designed by W7ZOI.

The circuit works perfectly, provides 5 Volts in the absence of signal, rises to 9 Volts at maximum signal.

My request for help is as follows:

Has anyone already tried to use an MC1590G in the bidirectional amplifier?

 Do you have any suggestions to give me?

Thank you

 

Re: 4x4 push pull IRF510s

Rod Davis
 

Hi Allison,

Thanks for your ideas on this subject.

Curious about your 4x4:

1. is the circuit topology  2 instances of 2x4 in push-pull, with a combiner?

2. do you bias each IRF510 separately?

3. any attempt to select IRF510s for equal parameters?

3. what do you suggest for idling current at 28v?

4. do you use BJT driver devices? If so, what device?

As always, Best Regards, 

Rod KM6SN



On 02/21/2018 03:19 PM, ajparent1 wrote:
There seems to be a belief that the IRF5xx parts have no capability at VHF...

I have an amp using 8 of them at 32V that puts out a mere 210W at 50mhz.  All of the parts are
IRF510s in a 4x4 push pull arrangement!  The amps gain over all is about 13db. 

I have also built the WA2eby push-pull HF amp and that design with 2w in gives me 55W at 40M
and 37W at 29mhz, that with a 28V supply.   Also IRF510s so the part has capability though
generally if performs better at 24V.

THe bias on the IRF510 is often lower than optimum, Both amps (and other HF/6M projects)
run far more bias current that specified as it produced more power.

The problem is the amplifier has matching issues from simplified transformers.  Additionally 
at 30mhz the AC  gain of the driver and predriver transistors (2n3904) is about 10 as compared
to an AC gain of 20 at 14mhz. So you seeing two problem one of driver that diminishes with
frequency and matching that is less than optimum with increasing frequency. 

I've also built amps around the RD16HHF part and at 13V its good but it requires different
components around it to get the power out they can deliver.  For a push pull pair with adequate
drive 20W is about it.

Before I'd go for changing parts I'd insure the driver and predriver are producing enough power.
It is also possible that the particular parts are on the low sid eof spec but the design is robust enough
to absorb that.

Another thing to insure is that your DC [pwer getting to the final is really 12-14V and not suffering
excessive voltage drop due to wiring  or worse the power source fading at higher currents.

So dropping in RD16HHF1 in without changes will likely not improve matters much and it may
lead to instability.   But if you have a pair you can try. 

I'd expect more like 4W or more so something is not right.


Allison/kb1gmx

Re: #ubitx replaced Arduino Nano gives a lot of I2C interference during reception #ubitx

Alex - PA1FOX
 

Thanks guys, I think it is a Nano version issue. I have picked up the I2C signals sent to the SI5351 on the scope and have a look at the following photo's:

Left is from the new Nano, right is from the old Nano. It seems that the new Nano sends more instructions to the SI5351 than the old one. SI5351 recognizes both commands. There could be something in the SI5351 library which is different for different Nano versions. 

Don't know if it makes the difference in clicks, but it is a lead.

Alex

#ubitx Calibration resolution #ubitx

ge_clipboard
 

Hello Ian

Where can I download v 1.03 of your software or the source to compile?

Another question I have, IF-Shift is working perfect in LSB-Mode but has =
no effect with USB-Mode. =3D Where should I have to look for, or ist =
this the momentary state?=20

Thanks for any information and 73, Gerald - HB9CEY

Re: #ubitx Calibration resolution #ubitx

 

Thanks Ian, that will help greatly. I figured I could do the calibration from the uBitx manager but didn't know what value to input there. I look forward to some detailed instructions on how to use the new features of the firmware and the uBitx manager. For the time being everything is working quite well.

Joel
N6ALT

Re: #ubitx replaced Arduino Nano gives a lot of I2C interference during reception #ubitx

MVS Sarma
 

John,
 I was seeing at different possibilities.
 Not i2c clicks alone.
 Thereby the FT-8 signalling on usb  cam eup as a thought.
Try to power and ground returen wires as a pair, from some common point  instead of leaving gnd return indirect.There I suggested to have filter on the power wire.( like LC pi filter.). If the rotary encoder is externally wired  (i mean not  on board), you need to decouple the encoder pins to ground close at NANO. Also try to use s shielded (screened pairor tripple that includes the switch wire) for connecting rotary encoder.
Perhaps you know all these tricks ,. already.
regards
 sarma
 vu3zmv

 

Regards
MVS Sarma
 

On Thu, Feb 22, 2018 at 8:03 PM, John <passionfruit88@...> wrote:
Alex,

I had the problem in reverse where the clicks where very noticeable with the factory nano as mounted on the Raduino. 

After  I changed the nano for a cheap eBay one, the clicks went away (as well as the audio tones I had).

This seems to indicate large variations in values of some components leading to part-to-parts variations.

Maybe better luck with the next one unfortunately.

All the best,

73, John (VK2ETA)


Re: Erratic Tuning bitx40!

Jodannastreet1985@...
 

Can I update to a later software? If so what are the benefits of this? Thanks

Re: Erratic Tuning bitx40!

Jodannastreet1985@...
 

Ok I will replace the pot. Thanks for the help guys. 

Re: Variable power control

Gordon Gibby <ggibby@...>
 

​Thanks -- great info.  3db insertionloss.  



From: BITX20@groups.io <BITX20@groups.io> on behalf of Karl Heinz Kremer, K5KHK <khk@...>
Sent: Thursday, February 22, 2018 9:34 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Variable power control
 
There is an HP application note about PIN diode attenuators: http://www.hp.woodshot.com/hprfhelp/4_downld/lit/diodelit/an1048.pdf

I was just about to recommend a PIN diode attenuator as well. The device used in this particular configuration reached it's end of life, and may be hard to get soon. There are alternatives: 

https://www.nxp.com/docs/en/data-sheet/BAP70Q.pdf

The data sheet has a chart that shows insertion loss based on frequency and control voltage. 
--
Karl Heinz - K5KHK

Re: Using external amp with µBitx

Lawrence Macionski <am_fm_radio@...>
 

Measure the unmodified volume control with a volt meter. It there is DC present, then couple your audio through a 1-2Uf non polarized capacitor. DC on the audio input can "turn off" that external amp.  You want audio. Not audio on top of some DC level.

Re: Variable power control

Karl Heinz Kremer, K5KHK
 

There is an HP application note about PIN diode attenuators: http://www.hp.woodshot.com/hprfhelp/4_downld/lit/diodelit/an1048.pdf

I was just about to recommend a PIN diode attenuator as well. The device used in this particular configuration reached it's end of life, and may be hard to get soon. There are alternatives: 

https://www.nxp.com/docs/en/data-sheet/BAP70Q.pdf

The data sheet has a chart that shows insertion loss based on frequency and control voltage. 
--
Karl Heinz - K5KHK

Re: #ubitx replaced Arduino Nano gives a lot of I2C interference during reception #ubitx

John <passionfruit88@...>
 

Alex,

I had the problem in reverse where the clicks where very noticeable with the factory nano as mounted on the Raduino. 

After  I changed the nano for a cheap eBay one, the clicks went away (as well as the audio tones I had).

This seems to indicate large variations in values of some components leading to part-to-parts variations.

Maybe better luck with the next one unfortunately.

All the best,

73, John (VK2ETA)

Re: #ubitx replaced Arduino Nano gives a lot of I2C interference during reception #ubitx

Alex - PA1FOX
 

Hi Sarma,

Thanks for your answer, any help is welcome, and I'm sure I will finally find out what's happening. It's also the fun of building your own rig, hey?

Please note, I am not using the Raduino, but a standard Nano and an Adafruit SI5351 board. Neither do I use a rotary encoder but the old 'analog' method of tuning, where the rigs start running up and down at the tuning pot's ends.

Currently I am 'walking around' with the oscilloscope probe to get a 'feeling' about the signal. It's clear that the ground copper clad around the audio amp is not clean from noise. I just need to find out why it does work with the old Nano. The supply and ground leads around the Nano and SI5351 boards are clean. The tuning pot leads are clean also. I can reduce the clicks slighty by connecting a heavy screwdriver from the metal cabinet to ground close to the audio amp.
Better grounding will help, but it's strange that with the old Nano it works without any noise. I can't imagine that the broken IO port actually helps in this case.

I'm confused as to what you mean with the CH340 USB chip with FT8. USB is not connected during the tests. Firmware is uploaded to both Nano's and then USB is disconnected

73, Alex

Re: Second batch of uBITX shipping? #ubitx

Daniel Conklin <danconklin2@...>
 

I am planning on it. See you there, God willing and the creeks don't rise...

Re: uBITx shipping and all

Gordon Gibby <ggibby@...>
 

Greedy governments.  


On Feb 21, 2018, at 22:35, walt hodges <walt.r.hodges@...> wrote:

what is your paypal address?

On Wed, Feb 21, 2018 at 1:26 AM, Lawrence Galea <9h1avlaw@...> wrote:
Disgusting Scrooges and Grinches
Most authorities these days would make you pay to breathe.


On Wed, Feb 21, 2018 at 7:03 AM, K9HZ <bill@...> wrote:

 

So I’m a big proponent of getting younger people involved in ham radio and to that end, I support the YOTA (youth on the air) initiative.  To that end I like donating time and radios to that cause, and what better first radio for a young ham than a nice new uBITx.  So in December, I ordered five uBITx transceivers to give away to young people on the island of St. Lucia (J6) where I have a retirement villa and nice radio station.  I work with another Ham on the island to bring in equipment that is difficult for hams to get there.  Well this week those five uBITx radios arrived and were stuck in customs until my friend there retrieved them.  The issue was, though, even though these radios were gifts for kids for learning… the St. Lucian government charged my friend $551 US Dollars today as import tax on those “FREE” radios.  Incredible.  I’ll have to make this right with him, but it’s getting harder and harder in today’s world to help people that need it.

 

 

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@...

 

 


Virus-free. www.avg.com



Re: Variable power control

Gordon Gibby <ggibby@...>
 

Thank you very much! I learned something from that.  Do you have any idea what is the minimum insertion loss?


On Feb 22, 2018, at 06:50, Roberto Vannucci <robertovannucci128@...> wrote:


I want to suggest a circuit that I have tested to regulate the power in my previous self-built HF transmitter. It is based on an HSMP3816 QUAD PIN DIODE.
I enclose the circuit file 73 IK6BLO

2018-02-22 9:33 GMT+01:00 Walter <W9KJO@...>:
Thank you very much

That is a very nice schematic drawing and readable

Thank you,  I cant wait to get the parts and build it.

73, W9KJO, Walter


<ss.bmp>