Date   

Re: Harmonic performance - SSB vs CW

m5fra2@...
 

Excellent, just shows that all is not lost and the BITX will live on!

 

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Warren Allgyer
Sent: 07 August 2018 13:20
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonic performance - SSB vs CW

 

The filter components as designed are perfectly adequate once the relay and layout problems are addressed. Yes, there are likely improvements that can be made with optimization but they are fine as is. 

I have removed the filter components from the uBitx and laid them out in a straight line on perf board. It is not pretty but that was not my intent..... I wanted to see how they perform. They perform superbly in this layout.

Photos of the board and the filter profiles are attached.

WA8TOD


Re: Harmonic performance - SSB vs CW

ajparent1/KB1GMX <kb1gmx@...>
 

I've used that many times.  In the 'EBY am p thats the filter selector and never had issues.
I've even gone back recently and retested as a verify and its good.

One thing keep the current under .3A for good lifetime if hot switching 
for static more is tolerated for SSB or CW use.  The .3A at 50 ohms
is 15W but it does seem to tolerate 55W without issues.  

Jameco.com
Two very low cost switches I've used.  
  • Manufacturer: Jameco Valuepro
  • Manufacturer no.: G3SR022-R
  • 2x6poistion make before break $1.95

  •  
  • Part no.: 576421     6 position 2.5A  $6.95
  • Manufacturer: C&K
  • Manufacturer no.: A20615RNZQ
I've used that exact part for a number of projects, seems to have endured hammerfisted users well.

Allison


Re: BITX40 LPF mod

Arv Evans
 

Jerry

I first came across that parallel cap and inductor trick when Dan Tayloe N7VE used it in the
BITX20A, and later the BITX17A.  It worked well there so I decided to try it with my early
version BITX40 from HFSignals.  No reason why it should not work with other transceivers
that use an LPF connected to the antenna. 

From LTSpice simulations this trick seems to work best with the inductor closest to the
antenna.  I did do several simulations with the parallel capacitor on the inductor closest
to the finals, but results were a bit discouraging.  My guess is that if the parallel LC is
on the RF PA side of the LPF then unwanted RF gets reflected back toward the finals and
does strange things.

This morning I posted more information for using an LCR series trap on the output to suck
out 2nd harmonic energy.  This too seems to work, at least in the LTSpice simulator.  Will
probably be trying this in the real circuit sometime in the next week or so. 

Arv
_._


On Mon, Aug 6, 2018 at 11:39 PM Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:
Don Cantrell ND6T documented this adjustment to the Bitx40 LPF in January of 2017:
    http://bitxhacks.blogspot.com/2017/01/nd6ts-suppression-of-pesky-2nd-harmonic.html


On Mon, Aug 6, 2018 at 09:14 PM, Arv Evans wrote:
With all the filter discussion regarding uBITX I decided to take a look at design of
the output filter on the BITX-40.


Re: Harmonic performance - SSB vs CW

Kees T
 

The manual switch I mentioned earlier is SR2612F-0206-21R0B-D8-N 


Re: BITX40 LPF mod

Arv Evans
 

Re.  BITX-40 LPF Mod
When I added the parallel capacitance to notch out the 3rd harmonic the simulator showed
a very narrow notch.  Today I tried adding a resistance in series with that parallel capacitor.
The result is a much broader notch at approximately 21 MHz, but still with 63 db of attenuation.
LTspice IV - BITX_40__output_filter_with_parallel_resonance_and_Series_Resistance.asc_032.png
The upper trace is frequency response and the lower trace shows phase shift.  Adding the resistor seems to have
tamed the phase shift so it does not show a dramatic transition at resonance of L7 and C3.

Next possibly illogical step is to notch out any 2nd harmonic energy at 14 MHz.  This was done with a series trap
(R3, C1, L4).  With R3 at 1.5 ohms this looks promising.
LTspice IV - BITX_40__output_filter_with_21MHz_parallel_resonance_and_14_MHz_Trap_with_Resistance.asc_035.png
Upper trace shows frequency response and lower trace is phase shift.   
Results look like (1) no additional insertion loss, (2) Reasonably broad notch at 14 MHz, and
The notch at 21 MHz is still there, and (4) overall LPF roll off still starts at 10 MHz.

Will this actually work in a real-world circuit?  It will be interesting to find out.  If it does work it
could insure that 2nd and 3rd harmonics can be reduced to way below FCC requirement for the
BITX-40 transceiver.  The trap idea is interesting because more traps could possibly be added
to take care of any 12 MHz IF leak-through, or any other spurious signal that looks like it might
be a problem. 

Could this approach be applied to the uBITX filter problem...maybe, but I will leave that to people
who are much smarter than myself.

Arv
_._



On Mon, Aug 6, 2018 at 10:22 PM Arv Evans <arvid.evans@...> wrote:
Glen VK3PE

That is something that can be tested.  It doesn't show in the simulator, but real-world
may be different.  When I get to actually wiring this it will be easy to test.
Thanks for the info.

Arv
_._

On Mon, Aug 6, 2018 at 10:18 PM Glenn <glennp@...> wrote:
Arv,
I read somewhere that its a good idea to drop the inductor value by 25% or so, (cant recall exact %) then calculate the parallel Cap value for the required notch.  Otherwise i think the RL is compromised.
Or my memory is suspect, quite possible........
vk3pe


Re: Harmonic performance - SSB vs CW

Jerry Gaffke
 

Like I said earlier, I'd be fine with plug in LPF's on a rig in this price class.

Those that want relay switching of the LPF's can buy an optional daughterboard to stuff into 
that same plug in socket.
Though relatively expensive, there are some nice small surface mount latching relays
if you want small and power efficient on that daughterboard.

My hack to the v3 that I have will be four straps, one at the output of each LFP into the antenna jack.
Rewire K3 as follows:
    K3-12 goes to K1-12
    K3-14 goes to T11-2
    K3-16 goes to ground

Remove the extra traces around the filters to avoid blow-by.

Insert one of the four straps as appropriate when switching bands.

The stock rig has all three relays powered down during receive, selecting the 30mhz LPF.
We could adjust the firmware to make use of KT1,2,3 for the input side of the LPF's,
this would also require powering KT1,2,3 and Q17,18,19 from the 12v rail instead of the TX rail.

I will instead simply remove the three relays, and put a second set of four straps there as well.

Jerry, KE7ER
 


On Tue, Aug 7, 2018 at 05:32 AM, Gordon Gibby wrote:

 

A simple-minded solution that will likely work for the one or more that I'll be using "manually" will be a SPDT switch on the outside end of each filter.   Cut the loooong return traces, rewire existing relays as needed, tiny little perfboard off to the side to hold 3 or 4 switches (depending on how many bands I really care about) and wire the outputs with some coax back into the circuit.   Rewrite software if needed to activate desired relays after a bit of rewiring.   Done   

 


Re: Harmonic performance - SSB vs CW

Kees T
 

Excellent job Warren and some nice pictures to boot.

Since you used the existing uBITX components, would your suggested next step be to provide a new LPF only board with relays or a manual switch ?  ....to be mounted on the uBITX board ?

On one of my earlier manually switched LPF designs, realizing that not just any DPDT switch would work, I ordered some "bandswitch rotary switches .....6 position x2 " from Mouser. They worked quite well. 

Which of the 4 filters are used for each band ?  

73 Kees K5BCQ 


Re: reverse polarity protection (ubitx.net)

Jerry Gaffke
 

The hfsignals WireUp instructions for power into the rig at the top of   http://www.hfsignals.com/index.php/ubitx-wire-up/
have a symbol that looks like headphones.
Some have mistaken it for a fuse, that's definitely the wrong position for a fuse.
The label on that symbol says "On/Off", so we can assume it's a power switch.

Here's an old post showing how I wired mine up:
    https://groups.io/g/BITX20/message/53016




On Tue, Aug 7, 2018 at 07:31 AM, Jerry Gaffke wrote:
My preferred solution:
    https://groups.io/g/BITX20/message/52904

The instructions for reverse polarity protecton on the uBitx WireUp page would be acceptable  
if they also showed a 3 Amp fuse in line with the +12v lead from the power supply.


uBITX portable build #ubitx

Daniel Conklin <danconklin2@...>
 

I have been fascinated with the popular paratrooper style transceiver kits.  When I saw the K7XPO build in the small Apache case it got my creative juices flowing.  I cut a piece of aluminum and formed it to hold the uBITX mainboard upside down in the case and at a slight angle.  There were a few logistical issues, but I managed to make it work. The center knob is currently RF attenuation and will hook up to the AGC miniboard once I get it finished.  The red momentary switch next to the middle plug on the right is a tune/spot switch.  The others will be function switches once I figure out the problem I'm having with pull-up resistors.  It's mounted by four small bolts and lock washers and nuts and sits in the box very solidly. The spaces on each side accommodate a 18650 battery pack and the microphone with the lid closed. I've already made some contacts with it, but I still have a couple of mods I want to complete, so It will be coming out of the box again for those soon.
73, Dan - W2DLC


Re: reverse polarity protection (ubitx.net)

Jerry Gaffke
 

My preferred solution:
    https://groups.io/g/BITX20/message/52904

The instructions for reverse polarity protecton on the uBitx WireUp page would be acceptable  
if they also showed a 3 Amp fuse in line with the +12v lead from the power supply.
A large Schottky would be preferable to a 1n4007 if using a shunt diode like that,
a 1n4007 at significant currents might have a forward voltage of a volt or more.

The drawing at the top of the polarity protection page on ubitx.net is wrong and best ignored:
    https://ubitx.net/ubitx-fix-reverse-polarity-protection/
I see two issues with that drawing:
1)  Jack has  +12v going through the barrel of the connector, that's not typical.
2)  If black is truly ground (as it should be on the provided wiring harness) then the shunt diode is reversed in the drawing
 
For a shunt diode scheme like that, be sure to have a fuse in the +12v lead.

A few people recommend a fuse in the ground lead too, but equipment grounding (3 wire plugs, RF ground rods, etc)
can give a path around that ground lead fuse.  I never bother.
 
Jerry


Re: Harmonic performance - SSB vs CW

iz oos
 

Warren, this proves the women that wounded the toroids made an excellent job. I had no doubt about that!


Il 07/ago/2018 14:22, "Warren Allgyer" <allgyer@...> ha scritto:
The filter components as designed are perfectly adequate once the relay and layout problems are addressed. Yes, there are likely improvements that can be made with optimization but they are fine as is. 

I have removed the filter components from the uBitx and laid them out in a straight line on perf board. It is not pretty but that was not my intent..... I wanted to see how they perform. They perform superbly in this layout.

Photos of the board and the filter profiles are attached.

WA8TOD


Re: Harmonic performance - SSB vs CW

 

Put a 2pf cap from in to out and compare. I curious!!

Raj

At 07-08-18, you wrote:
The filter components as designed are perfectly adequate once the relay and layout problems are addressed. Yes, there are likely improvements that can be made with optimization but they are fine as is.

I have removed the filter components from the uBitx and laid them out in a straight line on perf board. It is not pretty but that was not my intent..... I wanted to see how they perform. They perform superbly in this layout.

Photos of the board and the filter profiles are attached.

WA8TOD


Eprom

m5fra2@...
 

Forget last message fixed it!

 

Colin – M5FRA


Re: Instruction Manual needs revision #ubitx

N5KBP
 

Had the same thing here with version 4.3. as soon as I tell it to calibrate the vfo goes to 10 mhz and goes into transmit. I put my frequency counter on the output and adjusted the output to exactly 10.000.000 mhz from about 185 hz high. It took a count of 16 on the calibration screen. The only issue was that the sidetone would not cut off without power cycling the board.
--
N5KBP


Re: reverse polarity protection (ubitx.net)

Bill Cromwell
 

Hi,

I have been in and repaired radios (and other electronics) where that reverse diode has blown. The failure mode was dead short to ground so the rest of the gear was still protected.

When one of my daughters married Dr. Murphy I thought I would get a break from Murphy's Law. But instead I get extra!

73,

Bill KU8H

On 08/07/2018 09:34 AM, Mvs Sarma wrote:
the diode could be 1N540x a 3 amp device , as it is feared that diode
might blow faster than fuse (rule of MURPHY !!)
_._,_._,_
--
bark less - wag more


Re: One question only...

ajparent1/KB1GMX <kb1gmx@...>
 

Rigol is a satisfactory machine if used properly.  Its big advanatage is price, for what it is and can do its a deal
you can't even get the attention of Keysight (Hp ne Agilent now...) refurbished equipment for that kind of money.

That said..

I've seen people using HP do stupid things and claim but the machine said such and so.  I've done it the hard
way for decades and every time I get a piece of gear life gets easier and I had to learn to use it correctly.  Most
if not all of the measurements discussed are not hard to do and do not require exotic gear but will require patience
and knowing how to perform the measurement.

To that end a copy of EMRFD the section on tests and measurements is well worth it.

Allison


Re: Harmonic performance - SSB vs CW

Bill Cromwell
 

Hi,

Check to see if you (accidentally) banned him from your inbox. Our screens are busy places and it is easy enough to accidentally bump the wrong thing. Been there - done that.

Check your 'spam bin' and 'trash bin' or whatever your mail system calls it. You can correct it there if you find Glenn's posts.

73,

Bill KU8H

On 08/07/2018 04:03 AM, William R Maxwell wrote:
Can anybody explain why I am not receiving Glenn's posts on this subject
but I am receiving the responses he receives, such as this from Colin.
Yet, if I go to the group page to view Colin's reply, I can step back
to find Glenn's post. Why should they not be appearing as emails, as
they had previously, since we moved to groups.io

Bill, VK7MX
--
bark less - wag more


Re: One question only...

Bill Cromwell
 

Hi Walt,

I still believe the problems can and will be overcome. There should be a flurry of activity while all the Bitx machines get updated with the fixes. I am sure it won't be as simple as a patch made of old chewing gum and a rubber band but it won't be like giving up an arm and a leg, either. I could be wrong. I was wrong once. I thought I had made a mistake but I hadn't <evil grin>.

There ARE some things to say about people who 'buy a Rigol' and concluding their findings must be accurate. Some can use them and some can't. This is really not the place to be parading credentials. There are people who can get the results with or without a 'Rigol' and others who can't even if they are shown a screen print. Spending time on that won't really resolve anything and will just create hard feelings. We need everybody aboard to get this radio on course. We can be sure there are issues. Debates about who said what and when they said it will not correct the problems. Only create more problems and maybe doom the radio to the landfill.

I won't be putting mine on the air until I have some sturdy filters on the output muzzling the spew. I am expecting an eventual, practical resolution to the problems:) This how 'open source' works :)

73,

Bill KU8H

On 08/07/2018 12:29 AM, WaltR wrote:
Hello Bill,

Its very unfortunate that a well intended kit that was assembled with
questionable quality parts, circuit and several other anomalies beyond
my comprehension, is in its present quandary. The principals it appears,
had good intentions and are to be commended for that. However, they have
no authority in North America. In fact the Border agencies of both our
countries are probably raising their eyebrows over the entire fiasco,
If not they soon will be. As I said earlier in my position As XO on
board ship I can’t afford to run afoul of the authorities so my bitx 40
and ubitx have been destroyed. Sad really, I will be looking at the kits
from QRP LABS. Or maybe I should purchase a good used FT817.
As an aside I had SIGINT techs look at the harmonic signature on the
Harris, Wolfsburg and Bendix King gear and found them to exceed
requirements by 30%, but of course again I’m comparing caviar to
peanuts. My wife chastises me for my attitude ergo I’m at sea for 6
months of the year. I’m trying to do better hi hi. It’s no wonder I’m
not allowed in the house before dark.

The sheer number of builders, the responses in this group, would suggest
that there is a strong need for a simple affordable all band QRP rig,
that is a fact, It will be interesting to see what happens in the next
while.

In the research I have done there are some kits available from China,
Russia and also Malaysia , they may be more in cost but perhaps ???


On a final observation you can buy all kinds of brands of test gear but
there are only certain brands that are deemed to be certification
instruments when operated by a certified knowledgeable technician, just
because you go out and buy a Rigol
doesnt mean that now you are instantly an industry expert.

Early day tomorrow, anchors aweigh at 0400

cheers and 73
WRS
--
bark less - wag more


Eprom erased

m5fra2@...
 

I have accidently erased the eprom on my uBITX. How can it be restored?

 

Colin – M5FRA

 

 


Re: reverse polarity protection (ubitx.net)

MVS Sarma
 

the diode could be 1N540x a 3 amp device , as it is feared that diode might blow faster than fuse (rule of MURPHY  !!)