Date   
Re: Comparison of LPFs with SMD and Toroidal inductors

 

This test is NOT on a BITX board, the loss at 45MHz and 90MHz is a points for comparison
of both components. This was done on a test jig I made with 2 BNCs and hooked to a SA.


On Thu, Nov 29, 2018 at 07:56 PM, iz oos wrote:

Raj, is - 0.65 the total loss on a 50 ohm load for this filter on SSB? What is the CW loss on various bands?

 

Re: Comparison of LPFs with SMD and Toroidal inductors

 

Jerry,

At 29/11/2018, you wrote:
Raj and group,

Do the new inductors for the 45/90mhz LPF have to be a specific kind of shielded inductor?
Or can we get by with any old 1206 surface mount inductor?
Any one wont do Jerry! has to be a shielded variety with about 2 ohms DC resistance.


How much better are the results when L5,L7 are replaced with shielded
surface mount inductors? Are we legal without that change?
Changing the relays KT1/2/3 to Axicon (thanks to Mike Doty) results in reduced harmonics
which reduces the signals fed back to the first BiDi and therefore I see less spurs.
You may be legal with only this but every board I have tested behaves differently.

Just changing L5/7 reduces the spurs on all higher than 20M bands.
I also found that Farhan filter also does the same thing. Now this filter is at the output
of the amp.. I'd rather clean the input with L5/7.
Using both mods will or should improve the spurs further.


At one point, Raj saw better results with the torroids at L1,2,3,4 replaced with
shielded surface mount inductors. Is that still the case?
The reason I changed them was that L1 toroid was causing instability if anything
like my finger was near it. With the SMDs - no issues.

This one board is clean and legal. Puts out 10W/40M with 15mV rms at the mic in!
I can push it to 14W. Another stubborn board needs 35mV for the same Po.


There was some discussion about different coils in the various Axicom relays,
has it been determined that the higher current coils are required
to reduce coupling sufficiently?
I think the current probably is not important. Axicom's under contact does
the trick.


Ideally we would have web references to specific easily obtained
parts for the relays, caps, and inductors needed to clean up the uBitx.
Even better, perhaps somebody could provide a kit of appropriate parts.
But I think this should wait till a specific list of recommended mods is nailed down,
and we know that the results are repeatable.
There is a seller for the SMD inductor parts, I requested him to sell a small
number of them uninterested in small sales. He asked me to buy the whole
lot! Like 3000 !!

The 45MHz filter is lossy but better than the LP filter IMHO.


Would be very cool if there was a cheap way to see this trouble in a stock rig,
and to verify that it works better after the fixes have been applied.
For example, use a second receiver (a second uBitx?) to check uBitx transmissions
for the 12mhz spur and the 45mhz-DialFreq spur?
I assume the transmitted signal would have to be attenuated by 40dB or so
to prevent damage to the receiver, attenuate by an additional 43dB when
listening for spurs. And put rig under test plus dummy load in a Faraday cage.
Can the procedure include checks for harmonics, at least on the lower bands?

The previous method of adding a second 45mhz crystal filter is no longer recommended.
This new 330uH-51pf-330uH low pass filter to knock out the 90mhz harmonic of the 45mhz IF
goes into the same position as that 45mhz crystal filter did, but works better.
It does not attenuate the desired signal so much as the 45mhz crystal filter did.


Sarma asked:
will the smd inductors in post PA lpf mode, take that power?
Answer: NO

Raj said:
This has nothing to do with the spurs issues.
I believe that should read:
This has nothing to do with the harmonic issues.

Leave the post PA LPF's with the stock torroids, the new smd inductors will not take the power.
The harmonics thru the post PA LPF's at L11 through L22 are fixed by just swapping out
the relays at KT1,2,3 with Axicom relays, the stock relays are not very suitable for RF.
There are other methods of fixing the post PA LPF's, these involve adding extra relays,
or adding a band specific low pass filter external to the rig in line with the antenna coax.

We need to finish this up with a detailed and complete list of recommended mods
so folks can use their uBitx with confidence. Very few have a spectrum analyzer.

Jerry, KE7ER

Totally Absurd -- Farhan being questioned in a police station about doctored sat picture

Bill Meara
 

Re: Your Must Have Mods!

Wayne Leake
 

  A preamp can help on RX.
 But I suggest having a gain control.
 Start with a good antenna first.
 For the RX/TX LEDs, I have some RGBs that I will use the red and green. Have not figured out a use for the blue yet.
 I don't know if I will add a TX amp or not. I will be working with BITX40s and BITX20.
 If I need that much power, I can simply use my 706 MK II G.

 A good antenna made for the frequency in 8use is far better than a random tuned with a tuner.

 And I found out that adding 75 meter legs to a 40 meter antenna was like adding both a preamp and a linear. A heck of a lot of difference. For 75 meters, that is.

 YMMV
 Wayne WA2YNE

2.8inch display & front panel

Prathap Naidu
 

Hi

Just checking out the new test Front panel & test bezel for the 2.8 inch TFT display

 

best 73

Pop

VU2POP

Re: Software

Snowist
 

In files section here you can find correct sized files for your lcd

Re: Nextion White screen issue

Snowist
 

Try to power Nextion from somewhere else, power bank, etc to monitor its behavior. If something happens you can focus on LCD as it may be defective

Re: Your Must Have Mods!

_Dave_ AD0B
 

When you press the Key the display shows that you are transmitting and you hear the relay click. 

In my ubitx I have a built in sound card with a usb cable for sound control. I have a dpdt switch that I can switch it from ssb/cw to digital like ft8. It controls both mic input and speaker output.

Large heat sinks were installed with a fan and custom shroud. Running full power with out an antenna didn't overheat the transistors. 

Lastly I designed a linear regulator to power the radio and power it with an old laptop power supply. I power the finals directly with the laptop supply. 

New Shop open

 

I have just opened a new Shop and will be selling my kits and other goodies via the site from now on. Keeping track by hand via spread sheet was getting a bit much.

More zero beat kits are coming and should be up soon. I have 2-3 pre-orders that will still be taken care of.

The AVC auto volume control (AGC) is coming very soon and will have it posted soon as I can.

Thank you all none of this would have been possible without support from the groups

A Big thanks to KE2GKB for his help and support, he will also be a go to for support.

I will be adding more DiY radio related items very soon.

Shop.Kit-Projects.com
--
David

 N8DAH
Kit-Projects.com

Shop is open!

Re: Your Must Have Mods!

Doug W
 

On Thu, Nov 29, 2018 at 03:55 PM, inftechllc wrote:
Linear Amp Kit
You might want to do some reading here or over at http://ubitx.net/ about spurs and harmonics before you start thinking about amplifiers.  When you go from a whisper to a shout small problems can become big problems.
 
--
www.bitxmap.com

Re: Your Must Have Mods!

N5KBP
 

If you are going to go with the nextion the TR/RX light would be redundant. The Nextion display has a button/label that changes colors from green to red.

--
N5KBP

Your Must Have Mods!

inftechllc
 

I am working on a new larger enclosure (Desktop/Base) for my uBITX and wanted to know your must have mods/upgrades to add to the design.  I plan to include a nextion touch display and builtin power supply.   I am looking primarily for three mods:

  • Linear Amp Kit
  • PreAmp Kit
  • Tx/Rx Light setup

But would also like to know anyone's "must have" mods and upgrades.

Thanks in advance for all the help! 

Re: Winlink

Gordon Gibby <ggibby@...>
 

​ha, ha!!   Next time I see that elusive fella I'll be sure to tell him you appreciated the hours and hours he spent!


Cheers,


Gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of AndyH <ahecker@...>
Sent: Thursday, November 29, 2018 3:42 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Winlink
 
Thanks!  I feel a white noise/SDR test coming on.

I'm using your books - thank you for documenting your work with Winlink and ALE!  And please pass on a 'thank you' to Mr. Prepperdoc as well.

Andy

On Thu, Nov 29, 2018 at 01:56 PM, Gordon Gibby wrote:
Well, I suspect at LEAST 2 kHz.  I think mine is more like 1800 hz.  Optimal is probably 2.4 kHz
 
 If you’re short on bandwidth and things aren’t working, try the 500 Hz winmor mode in that should be better, if slower 
 


 

On Nov 29, 2018, at 14:06, AndyH <ahecker@...> wrote:

I've been using mine for Winlink as well.  My sloping 'S' shaped 40/20 attic dipole isn't optimum by any means, and I sometimes have to jump from station to station to get a reply, but it does move email through the network.

My mic connector is the 4-pin Kenwood type so I can move the Signalink between my TS-530S and the µBITX.

Doc Gordon - how wide should the bandwidth be for Winlink?  Heaven help me - there might be another tweak in the queue.  hi hi hi

73, Andy, KG5RKP 

Re: Winlink

AndyH
 

Thanks!  I feel a white noise/SDR test coming on.

I'm using your books - thank you for documenting your work with Winlink and ALE!  And please pass on a 'thank you' to Mr. Prepperdoc as well.

Andy


On Thu, Nov 29, 2018 at 01:56 PM, Gordon Gibby wrote:
Well, I suspect at LEAST 2 kHz.  I think mine is more like 1800 hz.  Optimal is probably 2.4 kHz
 
 If you’re short on bandwidth and things aren’t working, try the 500 Hz winmor mode in that should be better, if slower 
 


 

On Nov 29, 2018, at 14:06, AndyH <ahecker@...> wrote:

I've been using mine for Winlink as well.  My sloping 'S' shaped 40/20 attic dipole isn't optimum by any means, and I sometimes have to jump from station to station to get a reply, but it does move email through the network.

My mic connector is the 4-pin Kenwood type so I can move the Signalink between my TS-530S and the µBITX.

Doc Gordon - how wide should the bandwidth be for Winlink?  Heaven help me - there might be another tweak in the queue.  hi hi hi

73, Andy, KG5RKP 

Re: Winlink

Gordon Gibby <ggibby@...>
 

Well, I suspect at LEAST 2 kHz.  I think mine is more like 1800 hz.  Optimal is probably 2.4 kHz

 If you’re short on bandwidth and things aren’t working, try the 500 Hz winmor mode in that should be better, if slower 




On Nov 29, 2018, at 14:06, AndyH <ahecker@...> wrote:

I've been using mine for Winlink as well.  My sloping 'S' shaped 40/20 attic dipole isn't optimum by any means, and I sometimes have to jump from station to station to get a reply, but it does move email through the network.

My mic connector is the 4-pin Kenwood type so I can move the Signalink between my TS-530S and the µBITX.

Doc Gordon - how wide should the bandwidth be for Winlink?  Heaven help me - there might be another tweak in the queue.  hi hi hi

73, Andy, KG5RKP 

Re: Winlink

AndyH
 

I've been using mine for Winlink as well.  My sloping 'S' shaped 40/20 attic dipole isn't optimum by any means, and I sometimes have to jump from station to station to get a reply, but it does move email through the network.

My mic connector is the 4-pin Kenwood type so I can move the Signalink between my TS-530S and the µBITX.

Doc Gordon - how wide should the bandwidth be for Winlink?  Heaven help me - there might be another tweak in the queue.  hi hi hi

73, Andy, KG5RKP 

Re: Found one issue was Preamp question

Woody
 

Hi Don,
I pulled the board and tested with sig gen on input and only the scope on the output.  Same huge crossover distortion.  The
(simple) circuit looked OK and the + input bias was 1/2 Vcc.  That chip is going to the waste bin!

Have hundreds of 741 devices in the junque box.  Used one - Works great.
The output is terminated into the high side of a 1K pot.  The wiper feeds an old TBA-810 circuit for several watts (if I want it ;) of output audio.

Woody    KZ4AK

On 11/29/2018 18:21, Don, ND6T via Groups.Io wrote:
Try a 1458 instead. It has the same pin-out and is drop-in compatible with a much higher output capacity. I mention this since it appears that you are feeding a lower impedance than what it is capable of driving since that is the waveform that one would expect if doing so. What are you driving? I substituted an LM380 as an output AF amp in the V4 and it does very well. No pre-amp needed.
73, Don

Re: Found one issue was Preamp question

Woody
 

No, left open.  Had not experienced a problem before this.   But then, there is this ;)
A new board using a 741 is working great.
Woody  KZ4AK

On 11/29/2018 4:35, Skip Davis via Groups.Io wrote:
Woody the LM358 is a dual op-amp so did you terminate the unused op-amp? If not then it could be the cause of your distorted output.

Skip Davis, NC9O

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Re: Found one issue was Preamp question

Don, ND6T
 

Try a 1458 instead. It has the same pin-out and is drop-in compatible with a much higher output capacity. I mention this since it appears that you are feeding a lower impedance than what it is capable of driving since that is the waveform that one would expect if doing so. What are you driving? I substituted an LM380 as an output AF amp in the V4 and it does very well. No pre-amp needed.
73, Don

Re: OT: Farhan's satellite - ExseedSat-1 - Possible launch?

Ashhar Farhan
 

nothing is confirmed as of yet. let's keep discussing it out of this mailing list. i will post the confirmed date though.

- f

On Thu, Nov 29, 2018 at 10:42 PM Doug W <dougwilner@...> wrote:
15h15 hours ago
 
 

Now targeting December 2 for launch of Spaceflight SSO-A: SmallSat Express from Vandenberg Air Force Base.


--
www.bitxmap.com