Topics

uBitx Unfiltered

Warren Allgyer <allgyer@...>
 

I made the attached files for my own reference during work on my uBitx which I have now suspended. But I thought they might be helpful for those still engaged in trying to filter the radio with external LPF/BPF combinations. This was my uBitx with the filters completely removed so I could see what parameters would be needed for an external filter to work satisfactorily. There are four slides included. Here are my comments on each:

80,40,20 meter CW
- Power level set on each band individually to 5 watts
- Green display line represents the -43 dBc threshold
- Second harmonic on both 80 and 40 is somewhat problematic as are odd harmonics out to 13th

80,40,20 meter SSB
- Power level set on each band individually to 5 watts CW then 1 kHz tone input level adjusted to produce the same 5 watts
- Green display line represents the -43 dBc threshold
- Second harmonic on both 80 and 40 is somewhat problematic as are odd harmonics out to 9th

17, 15, 10 meter CW
- Power level set on each band individually to 2 watts
- Green display line represents the -43 dBc threshold
- Harmonics can all be removed with a simple 34 MHz LPF. The filter included in the uBitx is more than adequate

17, 15, 10 meter SSB
- Power level set on each band individually to 2 watts CW then 1 kHz tone input level adjusted to produce the same 2 watts
- Green display line represents the -43 dBc threshold
- 17 meter spurs represented by markers 1 and 2 are problematic because only a close spaced, single band BPF can be used to remove them.
- 15 meter spurs at the low end need to be addressed.
- A single filter cannot cover these bands because of the close spaced 17 meter spurs.
WA8TOD

ajparent1/KB1GMX
 

Warren,

That is indeed a mess.

One place to look is pull power to the amp.  Look at the output of the 9 element 30mhz filter
peak level should be under -10dbm.   The stuff you will see there is not good and varies
with CW and SSB.   Then look before the filter (with it disconnected).  IF you look at both
those spots with and with out the power amp operating you also get a different mix of
spurs with different amplitudes.   It is especially bad above 17M.  You get at the output
of the 34mhz low pass a mix of signals that changes if the power amp is working into
a dummy load or turned off.

It suggests unwanted coupling and board level current loops.  It appears to be some of it
is signals introduced into the 45mhz wide band amp after the crystal filter.  

The 30mhz low pass was stated as not being adequate from testing then and
would found to be so again.

7/28/2016 part of the email stream at the beginning on freelists.
For myself I'd grab a bag of latching relays and build band specific filters.  That we know
can work but while its repetitive circuits is not always simple to do well (or tune up).

Back then I was told I didn't know shit and so I stopped saying it as was not to beb said
I had all the work and testing on a bench proto to the contrary.  Back then it was
failed TRX Minima as it has all sorts of unwanted outputs using a 20mhz IF and
minimal filtering while trying to cover 3-30mhz.   That begat HF1 Dual conversion
with crystal oscillators for CIO and 2nd conversion from a two pole 45mhz LC filter
and morphed into beginning of uBitx by early 2017.   The first version only had
2 than a bit later three low pass filters for 3-30mhz.  The goal then was as is
now 3-30 and very few filters.  Parts availability were big divers as in variable
caps and coils.

Allison

Warren Allgyer <allgyer@...>
 

Alison

i have put my uBitx on the shelf and plan no further work on it. Just too many issues trying to make a Ford out of a tricycle. I put these up as an assist for those still trying. 

WA8TOD

ajparent1/KB1GMX
 

Warren,

To that we are both in the same pew.  Bandaids are turning to cardiac surgery.
Unfortunate that that is the case.

I've gone back to modernizing a old atlas that was a parts dog for fun.
A display, Arduino, and 5351 can do a lot for that one. 

Allison

iz oos
 

Ok, it will never be a Ford Cosworth, but at least LPF will polish the tricycle...


Il 28/ago/2018 19:53, "Warren Allgyer" <allgyer@...> ha scritto:
Alison

i have put my uBitx on the shelf and plan no further work on it. Just too many issues trying to make a Ford out of a tricycle. I put these up as an assist for those still trying. 

WA8TOD

Brent Seres/ VE3CUS
 

So if I buy LPFs from Hans, which bands would you recommend? Given that the even harmonics are fairly well attenuated, I'm assuming I could use 1 LPF for 2 bands (ie 40/ 30, 20/17)?? Given the current solar flux disaster,  I probably have several years to solve 15, 12 and 10. Alternately, the BPFs for each band.  I'm not ready to give up yet!

Joe Puma
 

I haven’t even build my uBitx yet. Maybe in the winter. Where can I have a look at these LPF’s from Hans. It’s not a killer for me. I’m sure I can still have fun with the radio, it will definitely be a digital mode radio for FT8 for sure so as long as it has a few uses, I’ll be fine. I’m not looking for perfection. 

Joe
KD2NFC 




On Aug 29, 2018, at 12:30 PM, Brent Seres <brentseres1@...> wrote:

So if I buy LPFs from Hans, which bands would you recommend? Given that the even harmonics are fairly well attenuated, I'm assuming I could use 1 LPF for 2 bands (ie 40/ 30, 20/17)?? Given the current solar flux disaster,  I probably have several years to solve 15, 12 and 10. Alternately, the BPFs for each band.  I'm not ready to give up yet!

Brent Seres/ VE3CUS
 

Hi Joe

www.qrp-kits.com

Alan de G1FXB
 

for Hans LPF's try

http://www.qrp-labs.com/lpfkit.html

Alan

On 29/08/2018 18:40, Brent Seres wrote:
Hi Joe

www.qrp-kits.com

iz oos
 

I would say LPF for 60-30-17-10meters bands and eventually 160m if you would like to use this band too (I think it could transmit as well on 160m)


Il 29/ago/2018 18:30, "Brent Seres" <brentseres1@...> ha scritto:
So if I buy LPFs from Hans, which bands would you recommend? Given that the even harmonics are fairly well attenuated, I'm assuming I could use 1 LPF for 2 bands (ie 40/ 30, 20/17)?? Given the current solar flux disaster,  I probably have several years to solve 15, 12 and 10. Alternately, the BPFs for each band.  I'm not ready to give up yet!

Kees T
 

I have Gerbers for 2 different LPF relay boards. Both support the Hans Summers plug-in QRP Labs LPFs. One has space for 4x LPFs like the existing uBITX LPFs and uses smaller Omron DPDT relays and the other has space for up to 6 LPFs and uses the "standard" DPDT relays which uBITX uses. The 4x board has a diode dot OR which makes it compatible with 3 existing Raduino control signals. The 6x board has 6 individual control lines which could be a 6x rotary switch or some type of decoder/driver which could interface to the 3 Raduino control bits (would require a code change for proper LPF selection).

Presently undergoing testing but the Gerbers will be made available. 

73 Kees K5BCQ

MadRadioModder
 

You gonna bake a batch of boards or is this left to the reader?

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Kees T
Sent: Wednesday, August 29, 2018 3:08 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBitx Unfiltered

 

I have Gerbers for 2 different LPF relay boards. Both support the Hans Summers plug-in QRP Labs LPFs. One has space for 4x LPFs like the existing uBITX LPFs and uses smaller Omron DPDT relays and the other has space for up to 6 LPFs and uses the "standard" DPDT relays which uBITX uses. The 4x board has a diode dot OR which makes it compatible with 3 existing Raduino control signals. The 6x board has 6 individual control lines which could be a 6x rotary switch or some type of decoder/driver which could interface to the 3 Raduino control bits (would require a code change for proper LPF selection).

Presently undergoing testing but the Gerbers will be made available. 

73 Kees K5BCQ


Virus-free. www.avg.com

--

…_. _._

Kees T
 

MRM,

Depends on how the testing turns out ;o)

Haven't decided yet. Anyone can order boards with the Gerbers and share with friends using the "$2 for 10 boards + postage" deals several board vendors have. I uploaded what the artwork looks like to the "Files" section under my call. The 4x version is specifically designed to work with the existing uBITX and use it's LPF parts. Feel free to ask questions 

73 Kees K5BCQ ....charging another windmill.

Guy N7BIR <sgbridge@...>
 

Joe,
Not sure that the QRPLabs’ LPFs will handle the uBitX power capabilities. 

Guy WB7SZI

iz oos
 

Ask Hans, if not ask the right capacitors that handle that power.

Il 29/ago/2018 22:33, "Guy N7BIR" <sgbridge@...> ha scritto:
>
> Joe,
> Not sure that the QRPLabs’ LPFs will handle the uBitX power capabilities. 
>
> Guy WB7SZI

iz oos
 

On the Site it says ' The Low Pass Filter kit can handle at least 10W safely' so it will.


Il 29/ago/2018 22:46, "iz oos" <and2oosiz2@...> ha scritto:

Ask Hans, if not ask the right capacitors that handle that power.

Il 29/ago/2018 22:33, "Guy N7BIR" <sgbridge@...> ha scritto:
>
> Joe,
> Not sure that the QRPLabs’ LPFs will handle the uBitX power capabilities. 
>
> Guy WB7SZI


Kees T
 

The QRP Labs website says   "The Low Pass Filter kit can handle at least 10W safely"

73 Kees K5BCQ.

MadRadioModder
 

Easily…

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Guy N7BIR
Sent: Wednesday, August 29, 2018 3:34 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBitx Unfiltered

 

Joe,
Not sure that the QRPLabs’ LPFs will handle the uBitX power capabilities. 

Guy WB7SZI


Virus-free. www.avg.com

--

…_. _._

jim
 


On Wednesday, August 29, 2018, 9:30:26 AM PDT, Brent Seres <brentseres1@...> wrote:


So if I buy LPFs from Hans, which bands would you recommend? Given that the even harmonics are fairly well attenuated, I'm assuming I could use 1 LPF for 2 bands (ie 40/ 30, 20/17)?? Given the current solar flux disaster,  I probably have several years to solve 15, 12 and 10. Alternately, the BPFs for each band.  I'm not ready to give up yet!
_._,_._,_



You get rid of the even harmonics by adjusting rv2/rv3 until they (the even harmonics) null out ...same on every push-pull amp

Jim

Warren Allgyer <allgyer@...>
 

All

Please understand that LPF will only be effective to bring CW into compliance. SSB compliance will require BPF for 17 through 10 meters. 

Then you have IMD to deal with .........  

WA8TOD