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

 

Nick,
Did you ever post the sketch for the TPA2016 AGC?

Aug
AG5AT

Smoking Genie

John 2e0eii
 

Hi Guys

can you give me some help i have popped R141 ,whilst working a station near Inverness who gave me 5/8/9 ,

Then Smoke !! luckily R141 let go ,

I would like to replace with a bigger value Resister by drilling 2 holes through the board to support the Resister with solder..

My question is : is the b40 board single or double printed circuit, my unit is shoehorned into its cabinet i don't want to pull it all out to find out ,

and don't want to do any more damage,

--
Regards John 2E0Eii

Re: Smoking Genie

M Garza <mgarza896@...>
 

Hi John,
It is a double sided board.
I would just remove the resistor and put in a 1/2 watt in its place.  Also, check the transistor (Q14) to make sure it didnt sacrifice itself also.

Good luck

Marco - KG5PRT

On Thu, Feb 15, 2018 at 4:02 PM, John 2e0eii <2e0eii@...> wrote:
Hi Guys

can you give me some help i have popped R141 ,whilst working a station near Inverness who gave me 5/8/9 ,

Then Smoke !! luckily R141 let go ,

I would like to replace with a bigger value Resister by drilling 2 holes through the board to support the Resister with solder..

My question is : is the b40 board single or double printed circuit, my unit is shoehorned into its cabinet i don't want to pull it all out to find out ,

and don't want to do any more damage,

--
Regards John 2E0Eii





Re: Smoking Genie

chris gress <Chrisg0wfh@...>
 

Un solder the smc resistor and fit a higher wattage resistor to the top of the PC it will do the job chris g0wfh 

On 15 Feb 2018 22:02, "John 2e0eii" <2e0eii@...> wrote:
Hi Guys

can you give me some help i have popped R141 ,whilst working a station near Inverness who gave me 5/8/9 ,

Then Smoke !! luckily R141 let go ,

I would like to replace with a bigger value Resister by drilling 2 holes through the board to support the Resister with solder..

My question is : is the b40 board single or double printed circuit, my unit is shoehorned into its cabinet i don't want to pull it all out to find out ,

and don't want to do any more damage,

--
Regards John 2E0Eii




Re: Smoking Genie

John 2e0eii
 

Thanks Marco for your reply a big help


On 15/02/18 22:11, M Garza wrote:
Hi John,
It is a double sided board.
I would just remove the resistor and put in a 1/2 watt in its place.  Also, check the transistor (Q14) to make sure it didnt sacrifice itself also.

Good luck

Marco - KG5PRT

On Thu, Feb 15, 2018 at 4:02 PM, John 2e0eii <2e0eii@...> wrote:
Hi Guys

can you give me some help i have popped R141 ,whilst working a station near Inverness who gave me 5/8/9 ,

Then Smoke !! luckily R141 let go ,

I would like to replace with a bigger value Resister by drilling 2 holes through the board to support the Resister with solder..

My question is : is the b40 board single or double printed circuit, my unit is shoehorned into its cabinet i don't want to pull it all out to find out ,

and don't want to do any more damage,

--
Regards John 2E0Eii






-- 
Regards John 2E0Eii

Re: Smoking Genie

John 2e0eii
 

Thanks for your help Chris and your feed back,


On 15/02/18 22:12, chris gress wrote:
Un solder the smc resistor and fit a higher wattage resistor to the top of the PC it will do the job chris g0wfh 

On 15 Feb 2018 22:02, "John 2e0eii" <2e0eii@...> wrote:
Hi Guys

can you give me some help i have popped R141 ,whilst working a station near Inverness who gave me 5/8/9 ,

Then Smoke !! luckily R141 let go ,

I would like to replace with a bigger value Resister by drilling 2 holes through the board to support the Resister with solder..

My question is : is the b40 board single or double printed circuit, my unit is shoehorned into its cabinet i don't want to pull it all out to find out ,

and don't want to do any more damage,

--
Regards John 2E0Eii





-- 
Regards John 2E0Eii

Re: RD16HHF1 in the uBITX #ubitx

Jerry Gaffke
 

The FET's are more linear with a high quiescent current.
Though the WA2EBY gets away with 10ma quiescent drain currents into the IRF510's
which is a considerably less linear device than the RD16HHF1's.
If planning on portable use, I'd definitely try something less than 500ma.


On Thu, Feb 15, 2018 at 01:20 pm, John wrote:
I will then leave the idle PA current near 500mA per device despite the current drain.

Re: RD16HHF1 in the uBITX #ubitx

Arv Evans
 

Hello

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.

Arv
_._


On Thu, Feb 15, 2018 at 3:26 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
The FET's are more linear with a high quiescent current.
Though the WA2EBY gets away with 10ma quiescent drain currents into the IRF510's
which is a considerably less linear device than the RD16HHF1's.
If planning on portable use, I'd definitely try something less than 500ma.

On Thu, Feb 15, 2018 at 01:20 pm, John wrote:
I will then leave the idle PA current near 500mA per device despite the current drain.


Re: Advice on selling Bitx40 on EBay

Michael Monteith
 

 Post it here or on FB if you accept Paypal.  I bought a uBitx off a fellow ham that was in the same boat. 

73, Michael
KM4OLT

Re: RD16HHF1 in the uBITX #ubitx

Jerry Gaffke
 

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

K9HZ <bill@...>
 

Like this:

 

 

 

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 Arv Evans
Sent: Thursday, February 15, 2018 4:43 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RD16HHF1 in the uBITX #ubitx

 

Hello

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.

 

Arv
_._

 

On Thu, Feb 15, 2018 at 3:26 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

The FET's are more linear with a high quiescent current.
Though the WA2EBY gets away with 10ma quiescent drain currents into the IRF510's
which is a considerably less linear device than the RD16HHF1's.
If planning on portable use, I'd definitely try something less than 500ma.

On Thu, Feb 15, 2018 at 01:20 pm, John wrote:

I will then leave the idle PA current near 500mA per device despite the current drain.

 


Virus-free. www.avg.com

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