Date   
Re: How to get rid of Local FM broadcast stations #ubitx

iz oos
 

A lowpass filter to eliminate the 88-108mhz makes little sense as the ubitx has it already. A highpass filter to remove the 0.5-1.6Mhz AM broadcasts make sense as the ubitx is unfiltered for it.


Il 24/dic/2019 04:01, "Jack, W8TEE via Groups.Io" <jjpurdum=yahoo.com@groups.io> ha scritto:
Jerry:

This is taken from a CQ article (A Cheap and Easy BCI Filter, CQ Magazine, August, 2016) and this is the response curve from that article:

Inline image

The original article was for a 100W system, and looked like this:

Inline image

I used Chuck Adam's Muppet technique to make a smaller version for the Forty-9er and eventually made one for the µBITX, too:

Inline image

On the QRP rig I left it in the line.

Jack, W8TEE


On Monday, December 23, 2019, 8:41:24 PM EST, Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:


Jack,

So what BCI filter do you like best?
Can you show us a response curve that you know goes with that particular filter.
Are filters with the small axial leaded inductors suitable for in-line with the uBitx antenna,
or do you only use those for a receiver?
What kind of caps do you use (I'd think 100v NPO)?

Digging around through old posts, I found that you had recommended several different AM BCI filters:

In this one your post shows little axial leaded inductors, the article has some big toroids, no idea if it is the same filter design (in pf and uH):
   https://groups.io/g/BITX20/message/39613

This one looks like the same values as the above article, but the graph is totally different (and I have no idea what the Y axis is):
    https://groups.io/g/BITX20/message/72920

This one has the same graph as the above article, but has totally different values:
    https://groups.io/g/BITX20/message/67270

There may be others, that was just what I found in 3 or 4 minutes.

I had just recommended that last one to VU3ONX, in part because of the graph, 
and because using T50-6 toroids seemed like a good idea on a 10w uBitx.
On the other hand, those inductors should choke off most of the 3.5+MHz energy so perhaps
the smaller axial leaded guys are fine.

Jerry, KE7ER 



On Mon, Dec 23, 2019 at 01:57 PM, Jack, W8TEE wrote:
Thanks, Gwen. Also, the filter has a very low insertion loss and costs under a couple of dollars to build for a QRP rig.

Inline image

--
Jack, W8TEE

Re: uBitx using 5 inch display

N7XG
 

This is the screen I have:

DIYmall NX8048T050 Nextion 5.0" UART HMI Intelligent Nextion LCD Display Module TFT 800x480 Resistive Touch Screen Panel for Arduino Raspberry Pi ESP8266

Re: FS: uBitX V5 Board Set - Brand New - Unused

Jim WB2LHP in MI
 

Sold!...Thanks Jeff!

Re: uBitx using 5 inch display

Mark Hatch
 

Yup. Just make sure you get the right Nextion file (see the directory AJ6CU IN the files section) I would recommend getting the enhanced Nextion. Version. Only a few dollars more and much faster gpu

mark

Re: TOPIC OF THE v3 v4 L5 L7 Mod GOT ME WONDERING

Jerry Gaffke
 

This is an addendum to posts   https://groups.io/g/BITX20/message/73902
and   https://groups.io/g/BITX20/message/73909
I'm trying to gather all my notes on v3,v4 mods into one place.

Here's an old post from KU4QO that makes clear how important it is to keep mike gain down.
    https://groups.io/g/BITX20/message/66744
If you raise the mike gain, the 45mhz IF distorts and starts creating spurs.
Mike found that spurs started getting bad on 10m when mike gain was turned up
such that the output power was only 1/4 Watt.  Not clear where RV1 was set
during his tests.  RV1 might be a better option for adjusting output power.

As mentioned previously, replacing Q20,Q21,Q22 with BFR93W's can help 
reduce the spurs.  An alternate transister that might be easier to obtain is the BFR106.

As mentioned previously, adding an outboard low pass filter is a good solution
for knocking down the harmonics.  This is probably the easiest and most thorough approach.

Harmonics on v3 and v4 boards can be reduced by replacing relays KT1,KT2 and KT3
with Axicom V23105-A5403-A201.    No need to replace the other two relays.
Some forum members were using Axicom V23105-A5303-A201, which have a 200ma
coil current instead of 400ma.  The lower coil current means more coil windings,
there was some discussion that this might mean more harmonics will get through,
though this was never fully sorted out conclusively.

A third option is to rip up a bunch of traces on the board and use the old relays
as per this wiki entry:  https://groups.io/g/BITX20/wiki/uBITX-spur-and-harmonics
I assume that's Allison's work, though am not sure.

Jerry


On Sun, Dec 22, 2019 at 09:49 AM, Jerry Gaffke wrote:
On v5 (and v6), the changes Farhan made to reduce the 45mhz-DialFreq spur are as follows:
   v5 has a new low pass filter at L31,L32,C205 to block the 90mhz harmonic of the 45mhz IF
   R26 is now 220 ohms, to increase current (and reduce distortion on large signals)
   Transistors Q20,21,22 are now BFR93W for lower distortion (less harmonics) at 45mhz

I have listed those in what I consider to be their order of importance.
Changing out the transistors is the most difficult, and the other two changes may well be
sufficient to reduce the spur enough to meet FCC regs. 

I suggest using a low temperature alloy such as ChipQuik if removing those transistors:
    https://www.adafruit.com/product/2660
You first wick away most of the old solder using solder braid and flux, then add a bit
of the ChipQuik as if it were normal solder.  If that ChipQuik is more than luke warm
(via either a soldering iron or a $20 hot air embossing gun) it will be molten, making
it easy to pluck the transistor off with tweezers.

ChipQuik will also be useful when removing the old relays, if replacing them with Axicom relays.
You must either replace those relays or use an external filter appropriate for each band
to prevent harmonics from going out on the air with a v3 or v4 rig.

Here's the discussion in the forum where Farhan developed those changes: 
     https://groups.io/g/BITX20/message/61645
Note that there are 70 messages in that thread, and there are other such threads.
That particular message doesn't mention the transistors, but the 2n3904's simply don't have
sufficient Gain-Bandwidth-Product to work well at 45mhz, and so distortion occurs 
which produces that 90mhz second harmonic.  But if the filter of L31,L32,C205 is successful
in preventing the harmonic from reaching the first mixer, that's most of the fix.

For better performance during receive, you might also want to change out Q10,11,12 
to the BFR93W's.  

How swapping out L5,L7 for shielded parts would reduce this particular spur
is a bit of a mystery to me, but could well be the case.  Shielded coils
would prevent high magnetic fields in the nearby final amp from getting back into
the IF amp, so worth doing if you have them on hand.  There were other 
problematic spurs beyond the 45mhz-DialFreq spur that this could cure.

There were a bunch of other changes around the audio amp for v5.  

If you have an LM386 or a non-DX branded TDA2822 working in the audio amp, that should be fine.
The discrete transistors of v4 worked well enough for many, but if you have trouble with distortion
or insufficient power it should be easy enough to patch in an LM386 or TDA2822.
That new 2n7000 is there in front of the audio power amp on v5 to reduce annoying PTT pops
in your received audio when keying the mike, but is not essential.

Lots of changes to the final power amp for transmitting, these bring up the transmit power 
on the higher frequencies.  Without these mods you may only get a watt or two at 30mhz,
while getting perhaps 10 watts on 3.5mhz.  But these mods are hardly worth the trouble.
I would just use an external linear such as the 10W linear from QRP-Labs if you need more power,
though you will need an appropriate attenuator between the uBitx and that amp.

Be careful of increasing mike gain beyond what's available in the design as shipped from hfsignals.
Increasing mike gain to compensate for loss of gain in the transmit power amp at higher frequencies means
larger signals in the IF amps, and thus more distortion in those amps and in the mixers,
and thus far far worse trouble with spurs which you won't be aware of unless you look it over good
with a spectrum analyzer.  The rig can sound fine on the air, and still be putting out significant
out-of-band spurs if the mike gain is too high.

Jerry, KE7ER

Re: How to get rid of Local FM broadcast stations #ubitx

Jack, W8TEE
 

Jerry:

This is taken from a CQ article (A Cheap and Easy BCI Filter, CQ Magazine, August, 2016) and this is the response curve from that article:

Inline image

The original article was for a 100W system, and looked like this:

Inline image

I used Chuck Adam's Muppet technique to make a smaller version for the Forty-9er and eventually made one for the µBITX, too:

Inline image

On the QRP rig I left it in the line.

Jack, W8TEE


On Monday, December 23, 2019, 8:41:24 PM EST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:


Jack,

So what BCI filter do you like best?
Can you show us a response curve that you know goes with that particular filter.
Are filters with the small axial leaded inductors suitable for in-line with the uBitx antenna,
or do you only use those for a receiver?
What kind of caps do you use (I'd think 100v NPO)?

Digging around through old posts, I found that you had recommended several different AM BCI filters:

In this one your post shows little axial leaded inductors, the article has some big toroids, no idea if it is the same filter design (in pf and uH):
   https://groups.io/g/BITX20/message/39613

This one looks like the same values as the above article, but the graph is totally different (and I have no idea what the Y axis is):
    https://groups.io/g/BITX20/message/72920

This one has the same graph as the above article, but has totally different values:
    https://groups.io/g/BITX20/message/67270

There may be others, that was just what I found in 3 or 4 minutes.

I had just recommended that last one to VU3ONX, in part because of the graph, 
and because using T50-6 toroids seemed like a good idea on a 10w uBitx.
On the other hand, those inductors should choke off most of the 3.5+MHz energy so perhaps
the smaller axial leaded guys are fine.

Jerry, KE7ER 



On Mon, Dec 23, 2019 at 01:57 PM, Jack, W8TEE wrote:
Thanks, Gwen. Also, the filter has a very low insertion loss and costs under a couple of dollars to build for a QRP rig.

Inline image

--
Jack, W8TEE

Re: bitx v6 is here

George
 

Dear Mr Ashhar: to the very worm 7805 I added back to back 7809 on the wires of 7805 and it works good! Thanks and best regards!

Re: uBitx using 5 inch display

Jack, W8TEE
 

This is the 5", but Al and I've also used a 7"

Inline image

Jack, W8TEE


On Monday, December 23, 2019, 7:24:57 PM EST, N7XG <dean@...> wrote:


Anyone out there in uBitx land that has used a 5 inch display with the uBitx?

--
Jack, W8TEE

FS: uBitX V5 Board Set - Brand New - Unused

Jim WB2LHP in MI
 

I just bought these but have decided to go in a different direction. These uBitX V5 Main and Raduino boards are brand new, unused, in the original packaging...$100 shipped...PayPal only...Thanks for looking...Jim WB2LHP

Re: TIA amps modification

George
 

I do my experiments over V4 board. About AGC - I think to use UA1FA schematic - very simple but good analog circuit: IF amp of the signal output filter 12 MHz - amplitud detector-DC amp. 2 transistors, 2 diods. V-control brings delay to detector and also manual control over RF gain. I do not know about MSA but if it works good that is the result you would like to get. As for me I like 2-Gate field- effect transistors - this is my practice, experience(old one) and no more. Thanks for the info. Bes regards!

Re: FS: ubitx20 plus Univ Gray Case

Bill Robbins
 

 It is sold. Thanks to all that inquired.

Merry Christmas


On Dec 23, 2019, at 8:38 PM, Bill Robbins <wa8cdu@...> wrote:



uBitx V4  from HFsigs.  Sorry

On 12/23/2019 8:06 PM, Jerry Gaffke via Groups.Io wrote:
No such thing as a "uBitx20".

Is it a uBitx, and if so, then what version?
Is it a Bitx40?
If it has a Raduino, then it is one of the above.

If it's not one of the above, then you will have to tell us in detail where in came from and when.
Could be a Bitx20, and if so it could have come from any number of sources.
Some of them quite different.

Jerry



On Mon, Dec 23, 2019 at 04:41 PM, Bill Robbins wrote:
I have started this and have lost interest.  No audio.  Powers up fine.  Universal Grey Case from  Amateurradiokits.com.  $65 shipped to lower 48.

Re: How to get rid of Local FM broadcast stations #ubitx

Jerry Gaffke
 

Jack,

So what BCI filter do you like best?
Can you show us a response curve that you know goes with that particular filter.
Are filters with the small axial leaded inductors suitable for in-line with the uBitx antenna,
or do you only use those for a receiver?
What kind of caps do you use (I'd think 100v NPO)?

Digging around through old posts, I found that you had recommended several different AM BCI filters:

In this one your post shows little axial leaded inductors, the article has some big toroids, no idea if it is the same filter design (in pf and uH):
   https://groups.io/g/BITX20/message/39613

This one looks like the same values as the above article, but the graph is totally different (and I have no idea what the Y axis is):
    https://groups.io/g/BITX20/message/72920

This one has the same graph as the above article, but has totally different values:
    https://groups.io/g/BITX20/message/67270

There may be others, that was just what I found in 3 or 4 minutes.

I had just recommended that last one to VU3ONX, in part because of the graph, 
and because using T50-6 toroids seemed like a good idea on a 10w uBitx.
On the other hand, those inductors should choke off most of the 3.5+MHz energy so perhaps
the smaller axial leaded guys are fine.

Jerry, KE7ER 



On Mon, Dec 23, 2019 at 01:57 PM, Jack, W8TEE wrote:
Thanks, Gwen. Also, the filter has a very low insertion loss and costs under a couple of dollars to build for a QRP rig.

Inline image

Re: FS: ubitx20 plus Univ Gray Case

Bill Robbins
 

uBitx V4  from HFsigs.  Sorry

On 12/23/2019 8:06 PM, Jerry Gaffke via Groups.Io wrote:
No such thing as a "uBitx20".

Is it a uBitx, and if so, then what version?
Is it a Bitx40?
If it has a Raduino, then it is one of the above.

If it's not one of the above, then you will have to tell us in detail where in came from and when.
Could be a Bitx20, and if so it could have come from any number of sources.
Some of them quite different.

Jerry



On Mon, Dec 23, 2019 at 04:41 PM, Bill Robbins wrote:
I have started this and have lost interest.  No audio.  Powers up fine.  Universal Grey Case from  Amateurradiokits.com.  $65 shipped to lower 48.

Re: FS: ubitx20 plus Univ Gray Case

Bill Robbins
 

Ok.  Sorry. I don’t have the packaging anymore so I’ll have to look on the board.


On Dec 23, 2019, at 8:07 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

No such thing as a "uBitx20".

Is it a uBitx, and if so, then what version?
Is it a Bitx40?
If it has a Raduino, then it is one of the above.

If it's not one of the above, then you will have to tell us in detail where in came from and when.
Could be a Bitx20, and if so it could have come from any number of sources.
Some of them quite different.

Jerry



On Mon, Dec 23, 2019 at 04:41 PM, Bill Robbins wrote:
I have started this and have lost interest.  No audio.  Powers up fine.  Universal Grey Case from  Amateurradiokits.com.  $65 shipped to lower 48.

Re: FS: ubitx20 plus Univ Gray Case

Jerry Gaffke
 

No such thing as a "uBitx20".

Is it a uBitx, and if so, then what version?
Is it a Bitx40?
If it has a Raduino, then it is one of the above.

If it's not one of the above, then you will have to tell us in detail where in came from and when.
Could be a Bitx20, and if so it could have come from any number of sources.
Some of them quite different.

Jerry



On Mon, Dec 23, 2019 at 04:41 PM, Bill Robbins wrote:
I have started this and have lost interest.  No audio.  Powers up fine.  Universal Grey Case from  Amateurradiokits.com.  $65 shipped to lower 48.

Re: V6 radino on V5 board?

mm0bef@...
 

I think the control cables are the same but the pin numbering for them have been reversed by mistake by Farhan in the v6 schematic. Ill figure this out when i get time to put screen in. Or ill check v5 and v6 code for the pin assignments that would tell if they are the same.
73
MM0BEF_____Brian

Re: How to get rid of Local FM broadcast stations #ubitx

Jerry Gaffke
 

I was wrong when I said this:
    "You need a low pass filter, not a high pass filter."
You are both sort of right.

The title of this thread is about FM broadcast, for which we should use a low pass
.
But VU3ONX is having trouble with an AM broadcast station.
Since the ubitx operates above the AM broadcast band, he wants a high pass filter.
And the two filters I pointed him to were both high pass.
I just got a couple words mixed up.

Hopefully, he doesn't also have a nearby FM broadcast station.

Jerry, KE7ER



On Mon, Dec 23, 2019 at 03:38 PM, Keven Pittsinger wrote:
The FM band is 88-108 MHz, IIRC.  The HF frequencies are 29.7 MHz on down for us.  You wanna stop the FM broadcast freqs, so you wanna use a low pass.
 
Hide quoted text

 


On Mon, Dec 23, 2019 at 4:01 PM Martin Potter <ve3oat@...> wrote:
Jerry wrote :
"You need a low pass filter, not a high pass filter."

No, high pass is correct.  Pass high frequencies, but block low frequencies.  Pass the HF stuff and block the lower frequency BC stuff.

The filters pointed to in the links are mis-labelled.  They are high-pass.  Capacitors across the top pass the high frequencies and block the lower frequencies.  Inductors going to ground drain off the low frequencies, letting the higher frequencies pass by.  High-pass, not low-pass.

If the interference is truly from the FM BC stations, and not their AM-band counterparts, then a low-pass filter would be appropriate.

73,
... Martin   VE3OAT



FS: ubitx20 plus Univ Gray Case

Bill Robbins
 

I have started this and have lost interest.  No audio.  Powers up fine.  Universal Grey Case from  Amateurradiokits.com.  $65 shipped to lower 48.

Bill

uBitx using 5 inch display

N7XG
 

Anyone out there in uBitx land that has used a 5 inch display with the uBitx?

Re: How to get rid of Local FM broadcast stations #ubitx

Keven Pittsinger
 

The FM band is 88-108 MHz, IIRC.  The HF frequencies are 29.7 MHz on down for us.  You wanna stop the FM broadcast freqs, so you wanna use a low pass.


On Mon, Dec 23, 2019 at 4:01 PM Martin Potter <ve3oat@...> wrote:
Jerry wrote :
"You need a low pass filter, not a high pass filter."

No, high pass is correct.  Pass high frequencies, but block low frequencies.  Pass the HF stuff and block the lower frequency BC stuff.

The filters pointed to in the links are mis-labelled.  They are high-pass.  Capacitors across the top pass the high frequencies and block the lower frequencies.  Inductors going to ground drain off the low frequencies, letting the higher frequencies pass by.  High-pass, not low-pass.

If the interference is truly from the FM BC stations, and not their AM-band counterparts, then a low-pass filter would be appropriate.

73,
... Martin   VE3OAT