Topics

Mini PA für my uBITX #ubitx

DC3MS
 

Hi. I cant thank Ashhar Farhan and Ian (KD8CEC) enough for bringing me back into ham radio.

The ubitx and Ians software are so much fun.

I just completed my little PA using eBay modules ( MRF186 + LPF Board ) and a NANO connected via i2c to control it.

Just wanted to share it.

Regards Mark, DC3MS

 

Art Boelke
 

Nice!

On Sat, Jan 12, 2019 at 2:46 AM Mark Schraven <mark.schraven@...> wrote:

Hi. I cant thank Ashhar Farhan and Ian (KD8CEC) enough for bringing me back into ham radio.

The ubitx and Ians software are so much fun.

I just completed my little PA using eBay modules ( MRF186 + LPF Board ) and a NANO connected via i2c to control it.

Just wanted to share it.

Regards Mark, DC3MS

 

Brian Arnott
 

Nice looking setup Mark. Any chance of more detail?

Regards

Brian

DC3MS
 

Thank you Brian.

The PA board is available on eBay from different sellers. The boards are also used in the MX-P50M. https://vk2qr.wordpress.com/2014/11/25/mx-p50m-hf-amplifier-review/
I added a tandem match from eb104.ru, 4 arduino relays for PTT and ATT (-6dB) and an optocoupler board for switching the LPFs.

The Nano is connected to the ubitx via i2c. I had to insert some lines to send the frequency and PTT info. A tight fit in Ians software, not much memory left.

I tend to forget to switch antennas when changing fom 40/80m to higher bands and blew up a few finals in the past, so the code in the amplifier demands a low power tune after band changes.

When transmitting and high SWR occurs, PTT is disabled.

ATT is enabled on 20-80m as my ubitx puts out more then 5W on These bands.

Will gladly share all details when interested,  

Art Olson
 

Mark

Great job. I would be interested in details also

Art
N2AJO

On Jan 12, 2019, at 7:10 AM, DC3MS <mark.schraven@...> wrote:

MX-P50M

Brian Arnott
 

Many thanks, will look forward to any updates on the info


On Sat, 12 Jan 2019 at 12:29, Art Olson via Groups.Io <olsonaj6927=yahoo.com@groups.io> wrote:
Mark

Great job. I would be interested in details also

Art
N2AJO
> On Jan 12, 2019, at 7:10 AM, DC3MS <mark.schraven@...> wrote:
>
> MX-P50M



AA9GG
 

LOVE your BitX "twins"!! 

Do you have a link for the PA module on ebay?  I see tons of the MRF186 but no pcbs for it...



Virus-free. www.avast.com

Timothy Fidler
 

https://www.ebay.com/itm/90W-HF-Power-Amplifier-For-FT-817-IC-703-SUNSDR2-PRO-KX3-QRP-Ham-Radio/182056979298?hash=item2a63710b62:g:d~UAAOSwP~tW6cCQ:rk:13:pf:0

this vendor is top-cc* in Shanghai - never used him  - this is simply answering the question.

There is probably only one mafr down in a tin shack somewhere in PRC and these legions of resellers.  He quotes it as  90 w Module which is bollocks. 

NB no LPF with this incarnation. some other vendors of the same basic  PCB have an LPF but it is the single relay for both in and out type - as per what the MX-P50 uses.

DC3MS
 



Right, the module seems to be sold by many different sellers in asia. Dont expect to get documentation or service, they just sell it.

The boards are named "XF-P100" and "XF-LPF-HF".  

I am not promoting these modules as the amp can be changed to whatever you like, i just wanted to control it via i2c using Arduino.


@Timothy : I have tried to run in on 24V and my Zetagi HP500 showed  90W output with 5W drive. Given the MRF186s specs, wheres the catch ?

 

 

 

DC3MS
 

Thank you Timothy.

Heres a link : https://www.ebay.com/itm/Assembled-LPF-low-pass-filter-90W-SSB-CW-AM-RF-HF-power-amplifier-HAM-RADIO/121965988356?hash=item1c65bd4a04:g:2kgAAOSwFxBXHHYO:rk:3:pf:0

 

Timothy Fidler
 

Reply : Some of the photos I have seen have marginal looking  OPTs on them as in things that look like longitudinally split core coaxial cores.

2.  THe fully assembled versions will have a heat sink based on something like 30 W dissip most likely.  When you look at the MRF 186 specs it is rather in efficient so 
heat,  when it is run at 90 W out continuously could be a real problem.  A modern mosfet RF Amp will be nominally 60 percent eff in class B but NOT this one.

3. Some of the units have a power supply capacitor that is marginal at 24 V supply. - It can be changed out - in fact the Ozzie Wordpress article may have mentioned that.

apart from that , no issues !  PS it would be fascinating to find out how so many of these VHF gemini pairs got left in a sack in PRC prior  to their being repurposed for current use  - I guess they were intended for some military project that was canned or a better device (higher efficiency) was found and these ones went begging.??

Bob Lunsford <nocrud222@...>
 

Got more options with an eBay search...
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=HF+Power+Amplifier+For+FT-817+IC-703+SUNSDR2+PRO+KX3+QRP+Ham+Radio&_sacat=0

Bob — KK5R

--------------------------------------------

On Sun, 1/13/19, Timothy Fidler <engstr@...> wrote:

Subject: Re: [BITX20] Mini PA für my uBITX #ubitx
To: BITX20@groups.io
Date: Sunday, January 13, 2019, 12:56 AM

https://www.ebay.com/itm/90W-HF-Power-Amplifier-For-FT-817-IC-703-SUNSDR2-PRO-KX3-QRP-Ham-Radio/182056979298?hash=item2a63710b62:g:d~UAAOSwP~tW6cCQ:rk:13:pf:0

this vendor is top-cc* in
Shanghai - never used him  - this is simply answering the
question.

There is probably
only one mafr down in a tin shack somewhere in PRC and these
legions of resellers.  He quotes it as  90 w Module which
is bollocks. 

NB no LPF
with this incarnation. some other vendors of the same
basic  PCB have an LPF but it is the single relay for both
in and out type - as per what the MX-P50 uses.

Bob Lunsford <nocrud222@...>
 

A consideration here is to wonder if any spurs, etc., get
amplified with the amp. May need more LPF's to keep it
within FCC specifications. Just a thought.

Bob — KK5R

--------------------------------------------

On Sun, 1/13/19, DC3MS <mark.schraven@...> wrote:

Subject: Re: [BITX20] Mini PA für my uBITX #ubitx
To: BITX20@groups.io
Date: Sunday, January 13, 2019, 2:58 AM



Right, the module seems to be sold by many
different sellers in asia. Dont expect to get documentation
or service, they just sell it.
The boards are named "XF-P100" and
"XF-LPF-HF".  
I
am not promoting these modules as the amp can be changed to
whatever you like, i just wanted to control it via i2c using
Arduino.


@Timothy : I have tried to run in on 24V and my
Zetagi HP500 showed  90W output with 5W drive. Given the
MRF186s specs, wheres the catch ?

DC3MS
 

The heat dissipation on 24V really is high - i stick to 13.8V and 30W on the meter.

The PA is still to be analyzed regarding spurs - this is going to be done in the near future.

 

Jerry Gaffke
 

More than just a thought.

Here's another:  a LPF won't cure the spurs, they can be lower in frequency 
than your fundamental.    With the mike gain cranked up as some do to get 
sufficient power out on the high bands, spurs can be 20x stronger (or worse)
than even the rather lax -43dbc spec of our beloved FCC.

The uBitx is marginal at best with regards to spurs and harmonics and IMD and residual carrier.
Excusable on a QRP rig perhaps, but I wouldn't slap a linear on it unless I had the gear
to verify that the uBitx had been modded sufficiently to have a clean signal.
 
On the other hand, I guess all those FCC guys are out on leave these days ....

Jerry


On Sun, Jan 13, 2019 at 02:43 AM, Bob Lunsford wrote:
A consideration here is to wonder if any spurs, etc., get
amplified with the amp. May need more LPF's to keep it
within FCC specifications. Just a thought.

DC3MS
 

Thank you for the reminder Jerry.

You are right, no question about that. 

Easy to "forget" the discussion about ubitx signal quality.

 

 

Bob Lunsford <nocrud222@...>
 

I confused "spur" with "harmonic." I see your point, though.
Thanks for making me, and possibly others, to think more
about the real culprits.

Actually, an amp is not really necessary because more
is achieved by a proper antenna and more antenna work.
Major problem is that many people do not turn up the gain
on their receivers and once this is done, the QRP rig is
usually heard. The next consideration is some other station
that is nearby that runs high power and covers up the QRP
signal.

It's ll part of the QRP World. I remember days of the HW-7 and
HW-8 and the experience gained there. QRP is more than a
simple technique, though. It's pickled with patience.

Bob — KK5R

--------------------------------------------

On Sun, 1/13/19, Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:

Subject: Re: [BITX20] Mini PA für my uBITX #ubitx
To: BITX20@groups.io
Date: Sunday, January 13, 2019, 11:34 AM

More than just a
thought.

Here's
another:  a LPF won't cure the spurs, they can be lower
in frequency 
than your fundamental.   
With the mike gain cranked up as some do to get 
sufficient power out on the high bands, spurs
can be 20x stronger (or worse)
than even the
rather lax -43dbc spec of our beloved FCC.

The uBitx is marginal at best
with regards to spurs and harmonics and IMD and residual
carrier.
Excusable on a QRP rig perhaps, but
I wouldn't slap a linear on it unless I had the gear
to verify that the uBitx had been modded
sufficiently to have a clean signal.
 
On the other hand, I guess all those FCC guys
are out on leave these days ....

Jerry


On Sun, Jan 13, 2019 at 02:43 AM, Bob Lunsford
wrote:

A consideration here is to wonder if any spurs,
etc., get
amplified with the amp. May need
more LPF's to keep it
within FCC
specifications. Just a thought.

DC3MS
 

Bob, i deeply respect long time hams sharing their vast knowledge with new-to-ham Operators,
but i really didnt expect this discussion to start.
Sure its not necessary, nor is it necessary that i recap an Heathkit SB101, SB610, SB620 and build
an extra Hamdesk in the basement to set the line up together with the just acquired SB200.
If i would do my antenna and CW work right, all i needed would be pixie monobanders for each band.
I am not complaining about objections regarding signal quality - i think that is pretty important.

Bob Lunsford <nocrud222@...>
 

Mark, I'm in the process of getting a BITX40 (waiting for
shipping notification and tracking number) and those
old Heathkit days are moving into hazy history and a
desire to never revisit them. The only thing I have now
is an HW-2036 2M for monitoring 52S mostly and a
RS HTX-252. I live in a 2M depressed area.

I've build nearly everything Heath had. Had an HW-104
and an SB-104 but the FT-450AT I had made them look
like WW1 submarines. I even had a Drake TR7 which
was to me the Cadillac of HF radios but the 450 was
much better for me. All that is gone now. Moving into
the HF Signals arena.

These Ubitx/TITX40 radios are great. It's a new kind
of technology to me with the Raduino. The UbitX is
surprisingly good on reception and this means from
500KHz to 30MHz.

Big question is, when will the V5 board be available?

Bob — KK5R

--------------------------------------------

On Mon, 1/14/19, DC3MS <mark.schraven@...> wrote:

Subject: Re: [BITX20] Mini PA für my uBITX #ubitx
To: BITX20@groups.io
Date: Monday, January 14, 2019, 1:23 AM

Bob,
i deeply respect long time hams sharing their vast knowledge
with new-to-ham Operators,
but i really
didnt expect this discussion to start.
Sure
its not necessary,
nor is it necessary
that i recap an Heathkit SB101, SB610, SB620 and build
an extra Hamdesk in the basement to set the
line up together with the just acquired SB200.
If i would do my antenna and CW work right, all
i needed would be pixie monobanders for each band.
I am not complaining about objections regarding
signal quality - i think that is pretty
important.

DC3MS
 

See - thats what i really like ham radio for. There is no technical or practical reason to spend month on getting the 50 years old HK equipment back in shape - except me finding it fascinating.

I could buy some up to date transceiver for the Money (or even half of it) , but thats just not my kind of fun. I always wanted a Heathkit. Even if its only because of its looks :) 

I also like the uBitx because of the Arduino, which is something i use on a regular basis. 

Just wanted to use a Nano to control a linear and try the i2c connection and a nextion.

No show-off. No really need. But i for sure see a difference in range on 40/80m running FT8 on my homemade HF2V vertical. And it was fun to put together.