Hello,

afte solded out an broken sma connector (port 1) I missed the part direct to the wire or the connector (see the picture).  Has anyone  information if this part is an resistor or capacitor and what is the value?

Thanks,

Martin

Just an experienced guess: Likely its a DC blocking capacitor. Replace
with a larger value NPO or COG dielectric capacitor.

Dave - WØLEV

On Wed, Jun 26, 2024 at 10:00 AM WaMa via groups.io <WaMa=gmx.net@groups.io>
wrote:

> Hello,
>
> afte solded out an broken sma connector (port 1) I missed the part direct
> to the wire or the connector (see the picture). Has anyone information if
> this part is an resistor or capacitor and what is the value?
>
>
>
> Thanks,
>
> Martin
>
>
>
>

--

*Dave - WØLEV*

Schematic shows a 10uFd capacitor.

If that is the picture of a pad at the connector I highly doubt 10uF
with pads that size and style and on an RF port. No possible way if it
is the picture I recall.


On 6/27/2024 12:08 PM, Lou W7HV via groups.io wrote:
> Schematic shows a 10uFd capacitor.
>

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

When a capacitor is near zero reactance, which that one should be as a
coupling capacitor, the drift will not matter.  It simply has to be near
zero ohms reactance at the low frequency end (although that should
calibrate out) and and not have any major impedance bumps to the upper
instrument limit. Most likely it is a 0.1uF low voltage chip or
something around that range. We know it won't be in the 1 or more uF
range with that pad layout, and the real worry would be a parallel
resonance in the component itself in the upper part of operating range.
Small low voltage multilayer chips are pretty good in that application,
like a .1 to .33 uF low voltage MLCC.

Because reactance is near zero the capacitance drift is meaningless. The
likely issues would be a self parallel resonance inside the part but
MLCC are pretty good about that.



Someone must have a schematic.


On 6/26/2024 1:07 PM, W0LEV wrote:
> Just an experienced guess:  Likely its a DC blocking capacitor.
> Replace with a larger value NPO or COG dielectric capacitor.
>
> Dave - WØLEV
>
> On Wed, Jun 26, 2024 at 10:00 AM WaMa via groups.io <http://groups.io>
> <WaMa=gmx.net@groups.io> wrote:
>
> Hello,
>
> afte solded out an broken sma connector (port 1) I missed the part
> direct to the wire or the connector (see the picture).  Has
> anyone  information if this part is an resistor or capacitor and
> what is the value?
>
> Thanks,
>
> Martin
>
>
>
> --
> *Dave - WØLEV
> *
>
>
>

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

10uF is probably correct.
Feeding a slow square wave through a 1 MEG resistor into my SAA-2N shows an RC time constant of over 5 seconds when observed with a 10 MEG scope probe.
Recent low voltage SMD ceramic caps can have high values even in the smaller sizes.
--John Gord

>
>
>
>
>
> On 6/26/2024 1:07 PM, W0LEV wrote:
>
>> Just an experienced guess:  Likely its a DC blocking capacitor.  Replace
>> with a larger value NPO or COG dielectric capacitor.
>>
>> Dave - WØLEV
>>
>> On Wed, Jun 26, 2024 at 10:00 AM WaMa via groups.io ( http://groups.io ) <WaMa=
>> gmx.net@groups.io > wrote:
>>
>>>
>>>
>>> Hello,
>>>
>>> afte solded out an broken sma connector (port 1) I missed the part direct
>>> to the wire or the connector (see the picture).  Has anyone  information
>>> if this part is an resistor or capacitor and what is the value?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Martin
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>> --
>> *Dave - WØLEV
>> *
>>
>
>
>
>
> (
> http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient
> ) Virus-free. www.avg.com (
> http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient
> )
>
> ( #DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2 )
>

I have a pdf of the schematic, but don't remember where I got it.  The https://nanorfe.com/nanovna-v2.html  website says schematics are available at https://github.com/nanovna-v2/NanoVNA2.

On the schematic I have the cap is shown as C1, 10u.