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Does it make sense? Abusing a BITX20a with a MiniVNAPro

 

Hello,
I connected two scope probes to my MiniVNA Pro and applied them to the un-powered BITX20a. Seems interesting.

This is the 11MHz Filter (between C53 and C89):


Center frequency of the filter should be about 11.001703MHz. Not sure if/how to trust the reported attenuation on the skirt.

I have calibrated the VNA using the probes "against" each other(transmission mode) and against a 50Ohm dummy load(reflection mode).

I applied the same method on the RF Filter, and I discovered that probably L4 needs adjustment (1 turn more?) because does not cover up to half of the 20m band.

This is the flattest response I was able to achieve, too low in frequency (the markers are the band edges):


Didn't expect too much from the experiment (impedance mismatch at minimum), but it seems to work, what do you think?

Giuseppe Marullo
IW2JWW - JN45RQ
 

Giuseppe,
I have been wanting to get someone to test our blocks on N2PK vna. I
just acquired one, but I haven't found time to hook it up. Can you
look at the amplifiers too? Specifically, I want to know the
impedances over the entire spectrum.
- farhan

On 5/26/13, Giuseppe Marullo <giuseppe@...> wrote:
Hello,
I connected two scope probes to my MiniVNA Pro and applied them to the
un-powered BITX20a. Seems interesting.

This is the 11MHz Filter (between C53 and C89):


Center frequency of the filter should be about 11.001703MHz. Not sure
if/how to trust the reported attenuation on the skirt.

I have calibrated the VNA using the probes "against" each
other(transmission mode) and against a 50Ohm dummy load(reflection mode).

I applied the same method on the RF Filter, and I discovered that
probably L4 needs adjustment (1 turn more?) because does not cover up to
half of the 20m band.

This is the flattest response I was able to achieve, too low in
frequency (the markers are the band edges):


Didn't expect too much from the experiment (impedance mismatch at
minimum), but it seems to work, what do you think?

Giuseppe Marullo
IW2JWW - JN45RQ




--
Sent from my mobile device
 

Me too curious, about the amplification impedances...

Not only over the entire spectrum, but for diffrent Classes verses VDD too...

On 26/05/2013, Ashhar Farhan <farhanbox@...> wrote:
Giuseppe,
I have been wanting to get someone to test our blocks on N2PK vna. I
just acquired one, but I haven't found time to hook it up. Can you
look at the amplifiers too? Specifically, I want to know the
impedances over the entire spectrum.
- farhan

On 5/26/13, Giuseppe Marullo <giuseppe@...> wrote:
Hello,
I connected two scope probes to my MiniVNA Pro and applied them to the
un-powered BITX20a. Seems interesting.

This is the 11MHz Filter (between C53 and C89):


Center frequency of the filter should be about 11.001703MHz. Not sure
if/how to trust the reported attenuation on the skirt.

I have calibrated the VNA using the probes "against" each
other(transmission mode) and against a 50Ohm dummy load(reflection mode).

I applied the same method on the RF Filter, and I discovered that
probably L4 needs adjustment (1 turn more?) because does not cover up to
half of the 20m band.

This is the flattest response I was able to achieve, too low in
frequency (the markers are the band edges):


Didn't expect too much from the experiment (impedance mismatch at
minimum), but it seems to work, what do you think?

Giuseppe Marullo
IW2JWW - JN45RQ




--
Sent from my mobile device

--
--
Due to ongoing technological advancement, many of electronic products
become obsolete within a very short period of time, creating a large
surplus of unwanted electronic products.
E-waste being produced could increase by as much as 500 percent over
the next ten years as the use of electronic equipment grows.

Lack of consensus and irresponsible way to deal with reuse, recycling
causes release of toxins into the environment. whereas most of the
materials used in electronic equipment can be reclaimed, recycled,
repaired and reused to produce new products.

Contaminants from e-waste enter the soil, air, and water. thus
entering food chain can Contaminate DNA permanently those of new born.

An average electronic-gazet can contain up to 1,000 toxins, including
lead, copper, cadmium, mercury, sulphur, Beryllium oxide, and other
heavy metals, that are known to damage the nervous system, kidneys,
causes cancer, brain mental impairment, thyroid problems, liver
problems, disrupt the endocrine system, and birth defects.

Although there is legislation that encourages recycling, repairing,
neutralizing of e-waste, it's our duty to enforce anti- dumping laws,
rather than dumping is necessary.

Please encourage recycling or reuse of E-waste.

?7?3? ?d?e? ?V?U?3?S?X?T?
 

Faharan and Sandeep,
more than willing to help but I do not own the right equipment for amplifiers.

Dynamic range of the MiniVNA Pro in transmission mode should be about 84dB, but without an attenuator probably I cannot do much.
I will see if I could arrange a 30dB attenuator or something like that before feeding the amplifier with the raw power of the MiniVNA Pro :)

Giuseppe Marullo
IW2JWW - JN45RQ

On 5/26/2013 10:31 AM, Ashhar Farhan wrote:
Giuseppe,
I have been wanting to get someone to test our blocks on N2PK vna. I
just acquired one, but I haven't found time to hook it up. Can you
look at the amplifiers too? Specifically, I want to know the
impedances over the entire spectrum.
- farhan

On 5/26/13, Giuseppe Marullo <giuseppe@...> wrote:
Hello,
I connected two scope probes to my MiniVNA Pro and applied them to the
un-powered BITX20a. Seems interesting.

This is the 11MHz Filter (between C53 and C89):


Center frequency of the filter should be about 11.001703MHz. Not sure
if/how to trust the reported attenuation on the skirt.

I have calibrated the VNA using the probes "against" each
other(transmission mode) and against a 50Ohm dummy load(reflection mode).

I applied the same method on the RF Filter, and I discovered that
probably L4 needs adjustment (1 turn more?) because does not cover up to
half of the 20m band.

This is the flattest response I was able to achieve, too low in
frequency (the markers are the band edges):


Didn't expect too much from the experiment (impedance mismatch at
minimum), but it seems to work, what do you think?

Giuseppe Marullo
IW2JWW - JN45RQ

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