Topics

Broadcast Interference filter for Ubitx

Laurence Oberman
 

Hello

In an earlier post Jack had shared his BCI filter design in reply to a
post where I was mentioning that my Ubitx V5 is sensitive to BCI.

For those who want a simple and effective way to do this I have one of
these from Amazon that works perfectly.
Its in-line and can handle the power easily and can be fitted in the
case using an SMA cable cut in half to make the connections.

https://www.amazon.com/gp/product/B076CVW6LC/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Jack, W8TEE
 

It sure looks nice. Still, mine cost me $0.87 to build, has a 0.04 dB insertion loss at 7MHz, with this shape characteristics:

Inline image
1.6MHz is down about -50dB.

Jack, W8TEE

On Wednesday, March 13, 2019, 2:26:14 PM EDT, Laurence Oberman <oberman.l@...> wrote:


Hello

In an earlier post Jack had shared his BCI filter design in reply to a
post where I was mentioning that my Ubitx V5 is sensitive to BCI.

For those who want a simple and effective way to do this I have one of
these from Amazon that works perfectly.
Its in-line and can handle the power easily and can be fitted in the
case using an SMA cable cut in half to make the connections.




Jim Sheldon
 

I just looked at the reviews on Amazon and it's not quite as good as they claim.  Someone did a plot of it using a Siglent 3022x spectrum analyzer and posted the results.  I've grabbed the image and here it is.


------ Original Message ------
From: "Jack Purdum via Groups.Io" <jjpurdum@...>
Sent: 3/13/2019 1:45:07 PM
Subject: Re: [BITX20] Broadcast Interference filter for Ubitx

It sure looks nice. Still, mine cost me $0.87 to build, has a 0.04 dB insertion loss at 7MHz, with this shape characteristics:

Inline image
1.6MHz is down about -50dB.

Jack, W8TEE

On Wednesday, March 13, 2019, 2:26:14 PM EDT, Laurence Oberman <oberman.l@...> wrote:


Hello

In an earlier post Jack had shared his BCI filter design in reply to a
post where I was mentioning that my Ubitx V5 is sensitive to BCI.

For those who want a simple and effective way to do this I have one of
these from Amazon that works perfectly.
Its in-line and can handle the power easily and can be fitted in the
case using an SMA cable cut in half to make the connections.




Laurence Oberman
 

Thanks, Yep Jack's is a better option but for those in a hurry, the interference I had was all AM up to 1680 Khz and for that it does OK,
I had bought this before Jack gave me hist schematic.
So far have not seen any issues with it on 40 and 20 but I agree, ymv (your mileage may vary)

The V5 was unusable without this and is acceptable now until I can get Jack's filter built.




On Wed, Mar 13, 2019 at 3:14 PM Jim Sheldon <w0eb@...> wrote:
I just looked at the reviews on Amazon and it's not quite as good as they claim.  Someone did a plot of it using a Siglent 3022x spectrum analyzer and posted the results.  I've grabbed the image and here it is.


------ Original Message ------
From: "Jack Purdum via Groups.Io" <jjpurdum@...>
Sent: 3/13/2019 1:45:07 PM
Subject: Re: [BITX20] Broadcast Interference filter for Ubitx

It sure looks nice. Still, mine cost me $0.87 to build, has a 0.04 dB insertion loss at 7MHz, with this shape characteristics:

Inline image
1.6MHz is down about -50dB.

Jack, W8TEE

On Wednesday, March 13, 2019, 2:26:14 PM EDT, Laurence Oberman <oberman.l@...> wrote:


Hello

In an earlier post Jack had shared his BCI filter design in reply to a
post where I was mentioning that my Ubitx V5 is sensitive to BCI.

For those who want a simple and effective way to do this I have one of
these from Amazon that works perfectly.
Its in-line and can handle the power easily and can be fitted in the
case using an SMA cable cut in half to make the connections.




Gary Anderson
 

Laurence, 
You have this filter installed in a receive only path, correct?  When you made a statement of inline and 'can handle the power easily' a caution flag went up.
Amazon / Nooelec Filter is rated for 5V pk-pk / 2.5V pk / 63mW.  Primary concern is the components (especially caps) are not rated to the required voltage to be suitable in the transmit path.

Regards,
Gary

Laurence Oberman
 

Hello Gary

Thanks for pointing it out, right now its NOT only the receive path
but I am only transmitting at 3w.
But I will be replacing it once I have the filter built Jack suggested.
I looked at receive path only on the Ubitx schematic when I first got
it but I figured its surviving 3W, and has done so for a while now.
The issue with all the cheap SDR filters are they are meant primarily
for receive only. :(

On the nooelec page when I first looked at it it had this which is
misleading because 18dbm is not "higher power"
Anyway I know I am pushing it but its surviving cw at the moment and
still working.
I did not need it on the V4.

"
DC current handling is 250mA (min), and the maximum recommended signal
level is +18dBm (5Vp-p), so there is no issue using the filter for
higher-power applications. Typical performance characteristics can be
found on the downloads tab of the product page on our website.
"
Thanks a lot for pointing it out as others would have not realized the
limitations.

Regards
Laurence

On Wed, Mar 13, 2019 at 6:17 PM Gary Anderson <gary.ag5tx@...> wrote:

Laurence,
You have this filter installed in a receive only path, correct? When you made a statement of inline and 'can handle the power easily' a caution flag went up.
Amazon / Nooelec Filter is rated for 5V pk-pk / 2.5V pk / 63mW. Primary concern is the components (especially caps) are not rated to the required voltage to be suitable in the transmit path.

Regards,
Gary

Skip Davis
 

Laurence you need to insert your BCI filter between relays K1 pin 12 and relay K3 pin 14. This will put your filter in the receiving path only.

Skip Davis, NC9O

On Mar 13, 2019, at 18:31, Laurence Oberman <oberman.l@...> wrote:

Hello Gary

Thanks for pointing it out, right now its NOT only the receive path
but I am only transmitting at 3w.
But I will be replacing it once I have the filter built Jack suggested.
I looked at receive path only on the Ubitx schematic when I first got
it but I figured its surviving 3W, and has done so for a while now.
The issue with all the cheap SDR filters are they are meant primarily
for receive only. :(

On the nooelec page when I first looked at it it had this which is
misleading because 18dbm is not "higher power"
Anyway I know I am pushing it but its surviving cw at the moment and
still working.
I did not need it on the V4.

"
DC current handling is 250mA (min), and the maximum recommended signal
level is +18dBm (5Vp-p), so there is no issue using the filter for
higher-power applications. Typical performance characteristics can be
found on the downloads tab of the product page on our website.
"
Thanks a lot for pointing it out as others would have not realized the
limitations.

Regards
Laurence


On Wed, Mar 13, 2019 at 6:17 PM Gary Anderson <gary.ag5tx@...> wrote:

Laurence,
You have this filter installed in a receive only path, correct? When you made a statement of inline and 'can handle the power easily' a caution flag went up.
Amazon / Nooelec Filter is rated for 5V pk-pk / 2.5V pk / 63mW. Primary concern is the components (especially caps) are not rated to the required voltage to be suitable in the transmit path.

Regards,
Gary

Laurence Oberman
 

Thank you Skip
Looked at Schematic when i first got it and was not finding the right place.
Will get that done tomorrow. Will save my filter even thiugh  its been good up to now

On Wed, Mar 13, 2019, 9:12 PM Skip Davis via Groups.Io <skipnc9o=yahoo.com@groups.io> wrote:
Laurence you need to insert your BCI filter between relays K1 pin 12 and relay K3 pin 14. This will put your filter in the receiving path only.

Skip Davis, NC9O
> On Mar 13, 2019, at 18:31, Laurence Oberman <oberman.l@...> wrote:
>
> Hello Gary
>
> Thanks for pointing it out, right now its NOT only the receive path
> but I am only transmitting at 3w.
> But I will be replacing it once I have the filter built Jack suggested.
> I looked at receive path only on the Ubitx schematic when I first got
> it but I figured its surviving 3W, and has done so for a while now.
> The issue with all the cheap SDR filters are they are meant primarily
> for receive only. :(
>
> On the nooelec page when I first looked at it it had this which is
> misleading because 18dbm is not "higher power"
> Anyway I know I am pushing it but its surviving cw at the moment and
> still working.
> I did not need it on the V4.
>
> "
> DC current handling is 250mA (min), and the maximum recommended signal
> level is +18dBm (5Vp-p), so there is no issue using the filter for
> higher-power applications. Typical performance characteristics can be
> found on the downloads tab of the product page on our website.
> "
> Thanks a lot for pointing it out as others would have not realized the
> limitations.
>
> Regards
> Laurence
>
>
>> On Wed, Mar 13, 2019 at 6:17 PM Gary Anderson <gary.ag5tx@...> wrote:
>>
>> Laurence,
>> You have this filter installed in a receive only path, correct?  When you made a statement of inline and 'can handle the power easily' a caution flag went up.
>> Amazon / Nooelec Filter is rated for 5V pk-pk / 2.5V pk / 63mW.  Primary concern is the components (especially caps) are not rated to the required voltage to be suitable in the transmit path.
>>
>> Regards,
>> Gary
>>
>
>
>




Gary Anderson
 

A quick look at the V5 schematic (relay changes over v3 and v4), it appears that the K3 relay pinout numbers now match standard relay pinout numbers (coil on 1,16). The K1 relay has not been updated in the schematic (old numbering scheme). It's not a big deal, if you are aware of it. K1 is drawn differently too (still the old way). It might be at first confusing to those that don't have tribal/historical knowledge and engage on V5.

Anyways, insert the BCI filter in the receive path board trace between K1 "pin 12"  and K3  as Skip highlighted.  (K3 no longer has a "pin 14", rather a "pin 11")

Rgds,
Gary

Laurence Oberman
 

Thanks Gary and Skip

On Thu, Mar 14, 2019 at 9:13 AM Gary Anderson <gary.ag5tx@...> wrote:

A quick look at the V5 schematic (relay changes over v3 and v4), it appears that the K3 relay pinout numbers now match standard relay pinout numbers (coil on 1,16). The K1 relay has not been updated in the schematic (old numbering scheme). It's not a big deal, if you are aware of it. K1 is drawn differently too (still the old way). It might be at first confusing to those that don't have tribal/historical knowledge and engage on V5.

Anyways, insert the BCI filter in the receive path board trace between K1 "pin 12" and K3 as Skip highlighted. (K3 no longer has a "pin 14", rather a "pin 11")

Rgds,
Gary

Sam Tedesco
 

Any issues with running the bci off to the side with thin coax or better to mount right on the rx line?

Laurence Oberman
 

The one i showed is well shielded but the board is too big to mount directly to the ubitx. You will need to run a shielded coax and can remove the sma connectors and mount on the side panel inside the box


On Tue, Mar 19, 2019, 8:16 PM Sam Tedesco <stedesco619@...> wrote:
Any issues with running the bci off to the side with thin coax or better to mount right on the rx line?

Skip Davis
 

There shouldn’t be any problem mounting off to the side via coax as long as it stays in the RX path.

Skip Davis, NC9O 

On Mar 19, 2019, at 20:16, Sam Tedesco <stedesco619@...> wrote:

Any issues with running the bci off to the side with thin coax or better to mount right on the rx line?

Sam Tedesco
 

Excellent! I would prefer to only cut the trace once. It. Looks like i can get mount points on the VIAs at the relays. Thanks, guys

Sam Tedesco
 

@Laurence... I picked up a filter to try. Is it really directional?

Laurence Oberman
 

Hi Sam i followed the in out on it but it works either way


On Fri, Mar 29, 2019, 11:26 AM Sam Tedesco <stedesco619@...> wrote:
@Laurence... I picked up a filter to try. Is it really directional?

Laurence Oberman
 

Also
Have not had time to put in recieve path only yet and its survived many 5w transmits
Its on my list when i rebuild with the qrp kits amp

On Fri, Mar 29, 2019, 11:32 AM Laurence Oberman <oberman.l@...> wrote:
Hi Sam i followed the in out on it but it works either way

On Fri, Mar 29, 2019, 11:26 AM Sam Tedesco <stedesco619@...> wrote:
@Laurence... I picked up a filter to try. Is it really directional?