Topics

Simpler spur fix

 

I found good reduction of spurs with the following mods:

1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid

2. Replace L7 as above.

The 45MHz filter is not required and you get almost the same power out as stock boards.

If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.

I used what I remember buying Murata inductors 1206 size.

Feed back will be appreciated.

With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

Cheers

--
Raj, vu2zap
Bengaluru, South India.

iz oos
 

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!


Il 10/ott/2018 09:06, "Raj vu2zap" <rajendrakumargg@...> ha scritto:

I found good reduction of spurs with the following mods:

1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid

2. Replace L7 as above.

The 45MHz filter is not required and you get almost the same power out as stock boards.

If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.

I used what I remember buying Murata inductors 1206 size.

Feed back will be appreciated.

With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

Cheers

--
Raj, vu2zap
Bengaluru, South India.





 

Oos it is!

Let us know your results.

When I checked many boards the spurs very higher in some than others. I discovered that the
physical position of L5 made a difference. Least spurs when vertical and more when horizontal.
Assumed that the tx signal was getting into the input of the BiDi amp. Better to stop at the input
and than amplify it and then filter it. 4 pole at Y1 did not matter at all but replacing L5 with SMD made
a big difference. There is an opinion that it must be ringing and SMD lower Q coil had made
the change!

I'll be back after 10-14 days at the farm, hope by then some of new relays will arrive for testing Mikes
relay fix.

Raj


At 10-10-18, you wrote:

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:

I found good reduction of spurs with the following mods:

1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid

2. Replace L7 as above.

The 45MHz filter is not required and you get almost the same power out as stock boards.

If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.

I used what I remember buying Murata inductors 1206 size.

Feed back will be appreciated.

With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

Cheers

--
Raj, vu2zap
Bengaluru, South India.





iz oos
 

Raj, can you show with a picture how you mounted L5 or L7, just to be double sure how to do that.


Il 10/ott/2018 10:25, "Raj vu2zap" <rajendrakumargg@...> ha scritto:
Oos it is!

Let us know your results.

When I checked many boards the spurs very higher in some than others. I discovered that the
physical position of L5 made a difference. Least spurs when vertical and more when horizontal.
Assumed that the tx signal was getting into the input of the BiDi amp. Better to stop at the input
and than amplify it and then filter it. 4 pole at Y1 did not matter at all but replacing L5 with SMD made
a big difference. There is an opinion that it must be ringing and SMD lower Q coil had made
the change!

I'll be back after 10-14 days at the farm, hope by then some of new relays will arrive for testing Mikes
relay fix.

Raj

At 10-10-18, you wrote:

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:

I found good reduction of spurs with the following mods:

1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid

2. Replace L7 as above.

The 45MHz filter is not required and you get almost the same power out as stock boards.

If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.

I used what I remember buying Murata inductors 1206 size.

Feed back will be appreciated.

With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

Cheers

--
Raj, vu2zap
Bengaluru, South India.





 

Emacs!

At 10-10-18, you wrote:

Raj, can you show with a picture how you mounted L5 or L7, just to be double sure how to do that.

Il 10/ott/2018 10:25, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
Oos it is!

Let us know your results.

When I checked many boards the spurs very higher in some than others. I discovered that the
physical position of L5 made a difference. Least spurs when vertical and more when horizontal.
Assumed that the tx signal was getting into the input of the BiDi amp. Better to stop at the input
and than amplify it and then filter it. 4 pole at Y1 did not matter at all but replacing L5 with SMD made
a big difference. There is an opinion that it must be ringing and SMD lower Q coil had made
the change!

I'll be back after 10-14 days at the farm, hope by then some of new relays will arrive for testing Mikes
relay fix.

Raj

At 10-10-18, you wrote:

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.
Feed back will be appreciated.
With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

iz oos
 

Thanks a lot!


Il 10/ott/2018 13:47, "Raj vu2zap" <rajendrakumargg@...> ha scritto:
Emacs!

At 10-10-18, you wrote:

Raj, can you show with a picture how you mounted L5 or L7, just to be double sure how to do that.

Il 10/ott/2018 10:25, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
Oos it is!

Let us know your results.

When I checked many boards the spurs very higher in some than others. I discovered that the
physical position of L5 made a difference. Least spurs when vertical and more when horizontal.
Assumed that the tx signal was getting into the input of the BiDi amp. Better to stop at the input
and than amplify it and then filter it. 4 pole at Y1 did not matter at all but replacing L5 with SMD made
a big difference. There is an opinion that it must be ringing and SMD lower Q coil had made
the change!

I'll be back after 10-14 days at the farm, hope by then some of new relays will arrive for testing Mikes
relay fix.

Raj

At 10-10-18, you wrote:

Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.
Feed back will be appreciated.
With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.

Mike Doty
 

Nice work Raj.  Looking at the photo it appears that you have the L7 smt coil connected between T4 and Y1, eliminating C211.  Is this correct or should the replacement coil connect between T4 and C211?
--73-- Mike

Jerry Gaffke
 

Good job, Raj!
That's looking like a very easy spur fix.

The 680nH inductors in your photo are larger than the adjacent 1206 parts in your photo.
But I'd bet 1206 inductors will do just fine.

Your photo shows that the SMD inductor replacing L7 is going around C211.
I doubt there's an issue with this, since the mixer should not have any DC there,
Anyone see a reason not to do this?.
Avoiding the C211 traces is a good thing.

Note that C210 and C216 are not stuffed in a stock uBitx (schematic says 0pF). 
Raj has left them unstuffed.

Jerry, KE7ER


On Wed, Oct 10, 2018 at 04:47 AM, Raj vu2zap showed a photo of his mods

On Wed, Oct 10, 2018 at 12:06 AM, Raj vu2zap wrote:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.


 

Mike, this works fine without bending too much to fit. I put them where I thought the issue would be fixed.
The 0.1uFs are redundant as there is no DC around that area.

Raj

At 10-10-18, you wrote:
Nice work Raj. Looking at the photo it appears that you have the L7 smt coil connected between T4 and Y1, eliminating C211. Is this correct or should the replacement coil connect between T4 and C211?
--73-- Mike

ohwenzelph
 

I like this, but...

looks like you left C215 in but took C211 out of the circuit, does it matter? Maybe not..
are you sure they are Murata? Are they shielded? Probably not exactly 1206, maybe 1210.
does shielding matter, does the self resonant frequency matter? If it works, I just want to be able to duplicate it!
thanks so much

Michael Maiorana
 

I'd like to second this question about the required inductors. Is it that the SMD inductors have a lower Q, or is it the smaller physical size, or the change in position, or a combination of all these changes?

Thanks
Mike M.
KU4QO 


On Wed, Oct 10, 2018 at 12:01 PM ohwenzelph via Groups.Io <Ohwenzelph=yahoo.com@groups.io> wrote:
I like this, but...

looks like you left C215 in but took C211 out of the circuit, does it matter? Maybe not..
are you sure they are Murata? Are they shielded? Probably not exactly 1206, maybe 1210.
does shielding matter, does the self resonant frequency matter? If it works, I just want to be able to duplicate it!
thanks so much
_._,_._,_


 


Sorry Owen,

Missed your reply.

I put the inductors in a convenient place without obliterating the component legends.

The seller on eBay had mentioned that they were Murata, the size may be 1210, slightly fatter than 1206.

Shielding the toroid made a slight change but this issue may be because of hi Q ringing. I just soldered them
as I saw fit and placed them at right angles to the toroid. That worked.. it also works in the exact place or
the old toroids.

Mike:

I think a combination of Q and small size and probably they are internally shielded I don't know.
I also replaced L1-4 with 330nH SMD and that helps a little on one test board.

My interest was to fix these problem with the simplest solution without major surgery. The next gen
board will probably be bigger with more inexpensive relays like two relays per filter.

The Axicom relays cost me about 5$ landed and taxed.. I am only going to change KT1,2,3 but in
production the cost has to be kept down in true BITX spirit.

Raj


At 12/10/2018, you wrote:
I'd like to second this question about the required inductors. Is it that the SMD inductors have a lower Q, or is it the smaller physical size, or the change in position, or a combination of all these changes?

Thanks
Mike M.
KU4QOÂ

On Wed, Oct 10, 2018 at 12:01 PM ohwenzelph via Groups.Io <Ohwenzelph= yahoo.com@groups.io> wrote:
I like this, but...

looks like you left C215 in but took C211 out of the circuit, does it matter? Maybe not..
are you sure they are Murata? Are they shielded? Probably not exactly 1206, maybe 1210.
does shielding matter, does the self resonant frequency matter? If it works, I just want to be able to duplicate it!
thanks so much

Jerry Gaffke
 

In post     https://groups.io/g/BITX20/message/60519
Lawrence Galea pointed out a Hong Kong source for Axicom relays at $0.98 USD for quantity 1,
$0.60 USD for quantity 1000. 
If those are genuine, or perform as well as genuine, that might be a good source for HFSignals.

Jerry


On Fri, Oct 12, 2018 at 06:47 AM, Raj vu2zap wrote:
The Axicom relays cost me about 5$ landed and taxed.. I am only going to change KT1,2,3 but in
production the cost has to be kept down in true BITX spirit.

mark bodlovich
 

Been looking around for the 1210 680nh inductors and cannot find a source yet. I noticed some suppliers only sell in very large quantities like 2000. So has anyone found a source yet or if so would be willing to sell a few to us who want them. Just putting it out there for consideration. Please pm me to make arrangements. 73 n7hwr

Jack Zielke
 

Do you think mounting the original toroids on the bottom of the board would work?

 

1206 version is available at Digikey 535-11689-1-ND

Cheers,
Jim W0CHL

 

I ordered a sample book from China.. good for experiments.

Raj

At 13/10/2018, you wrote:
Been looking around for the 1210 680nh inductors and cannot find a source yet. I noticed some suppliers only sell in very large quantities like 2000. So has anyone found a source yet or if so would be willing to sell a few to us who want them. Just putting it out there for consideration. Please pm me to make arrangements. 73 n7hwr

 

I did that and it did not help much!

Raj

At 13/10/2018, you wrote:
Do you think mounting the original toroids on the bottom of the board would work?

K5ESS
 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of mark bodlovich
Sent: Friday, October 12, 2018 7:10 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Simpler spur fix

 

Been looking around for the 1210 680nh inductors and cannot find a source yet. I noticed some suppliers only sell in very large quantities like 2000. So has anyone found a source yet or if so would be willing to sell a few to us who want them. Just putting it out there for consideration. Please pm me to make arrangements. 73 n7hwr

 

I think the 1210 shielded one would be best!

Raj


At 13/10/2018, you wrote:
Mouser  https://www.mouser.com/Passive-Components/Inductors-Chokes-Coils/Fixed-Inductors/_/N-wpcz?P=1z0wqjeZ1z0z7ymZ1yzvlko
Mike
K5ESS
 
From: BITX20@groups.io [ mailto:BITX20@groups.io] On Behalf Of mark bodlovich
Sent: Friday, October 12, 2018 7:10 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Simpler spur fix
 
Been looking around for the 1210 680nh inductors and cannot find a source yet. I noticed some suppliers only sell in very large quantities like 2000. So has anyone found a source yet or if so would be willing to sell a few to us who want them. Just putting it out there for consideration. Please pm me to make arrangements. 73 n7hwr