Re: Cheap Chinese Linear LPF
On Thu, Jun 3, 2021 at 06:09 PM, kx4om wrote:
Are you familiar with the Youtube channel "Applied Science"? The engineer who runs it has some interesting videos:
Yes, that is one of my favorite you-tubers. I like how he used crushed light bulbs as a cathode in his spectrometer. I have a surplus Pirani vacuum gauge that I'm using now, but am interested in seeing how crushed light bulbs might work for making a DIY vacuum gauge.? Here are a couple of other channels I like: BigClive Fran Lab Tech Ingredients Applied Science Technology Connections Tim Hunkin (Great... Now when I want to find one of these channels all I need to do is refer to the handy bookmarks, above.) There are several physics and math channels I like also. When I switched to doing software engineering after many many years of just doing ones and zeros, I need as much refresher as I possibility can get.? One more interesting use of crushed lightbulbs. A person who "served" on Antartica for a year gave a talk at a club meeting. One on the experiments measured the outside temperature at an remote station using 100 watt light bulbs with the envelopes broken off. For some reason they needed very fast response time, and the light bulb filaments did the job. ? Tom, wb6b
|
Right. Thanks Farhan. And have a good weekend!
Rafael
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Show quoted text
On 6/4/21 9:15 AM, Ashhar Farhan wrote: It is too early to think about that.
The sbitx is an add-on for existing radios with a little bit of
modification to the crystal filter. I am designing a new radio to go
with it.?
But, the ubitx, as a product, will continue as an all analog radio.
- f
On Fri, Jun 4, 2021 at 11:15 AM Rafael Diniz <rafael@...
<mailto:rafael@...>> wrote:
Dear Farhan,
Do you plan to "deploy" sBITX as uBitx, with pre-assembled selling and
so on?
Thanks,
Rafael Diniz
On 6/2/21 5:01 PM, Ashhar Farhan wrote:
> Oops, I send to the wrong?email addy. Sorry about that. this was
meant
> for Bill.
> - f
>
> On Wed, Jun 2, 2021 at 7:28 PM Ashhar Farhan via groups.io
<>
> < <>>
<farhanbox@... <mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
>? ? ?Bill,
>? ? ?The only time I used gilbert cell (NE602) was to build the
21 MHz
>? ? ?to 29 MHz transponder. The nearest station would be at least 500
>? ? ?KM away and the Yagis of the bad boys would be pointing
along the
>? ? ?ground towards each other. Isn't it an active mixer?
>? ? ?The KISS mixer is a passive mixer. The FETs are used as
switches,
>? ? ?not as amplifiers. The big deal is this: In a diode mixer, the
>? ? ?diodes are turned on by the switching current that flows along
>? ? ?with signal current through the same paths. In the FET switching
>? ? ?mixer, there is no switching current, and the switch is
turned on
>? ? ?by driving the gate very hard and almost instantaneously - that
>? ? ?makes it so resilient?to any reflected current coming back from
>? ? ?the filter side.?
>? ? ?SDR aside, the KISS mixer, theoretically consumes zero drive
>? ? ?power. It just needs a square-wave voltage to switch. It
makes for
>? ? ?a great analog front-end. That's what I tried with the Minima, I
>? ? ?should have used multiple band pass filters and added CW and
AGC,
>? ? ?it would have made a great radio. I might still do that!
>? ? ?I just got a strip of 100 40 MHz, fundamental crystals. Let
me see
>? ? ?if I can hammer out a filter with them. If it works, then I can
>? ? ?extend the sBITX to full 30 Mhz coverage.
>? ? ?I must read up on the Gilbert cell, EMRFD has devoted quite
a few
>? ? ?pages to it.
>? ? ?- f
>
>? ? ?On Wed, Jun 2, 2021 at 3:22 PM Rafael Diniz
>? ? ?<rafael@... <mailto:rafael@...>
<mailto:rafael@... <mailto:rafael@...>>>
wrote:
>
>? ? ? ? ?One question: Which is the transmit and receive bandwidth of
>? ? ? ? ?the sBITX?
>
>? ? ? ? ?How to buy or build one? (Without the Raspberry Pi, as the
>? ? ? ? ?need for
>? ? ? ? ?processing I have is much higher of what the Raspberry can
>? ? ? ? ?provide - I
>? ? ? ? ?need at least AVX2 4th gen Intel chip for ML purposes).
>
>? ? ? ? ?Thanks,
>? ? ? ? ?Rafael Diniz
>
>? ? ? ? ?On 6/2/21 12:04 PM, Rafael Diniz wrote:
>? ? ? ? ?> Thanks a lot!
>? ? ? ? ?>
>? ? ? ? ?> Reading the names of Farhan and Phil Karn makes me
shiver! Wow!!
>? ? ? ? ?>
>? ? ? ? ?> You are the ones!!!
>? ? ? ? ?>
>? ? ? ? ?> Rafael
>? ? ? ? ?>
>? ? ? ? ?> On 6/2/21 11:32 AM, Shirley Dulcey KE1L wrote:
>? ? ? ? ?>> I should?add that it's a transceiver design, not just a
>? ? ? ? ?receiver.
>? ? ? ? ?The
>? ? ? ? ?>> DSP is done by a Raspberry Pi 4. The talk first
presents a
>? ? ? ? ?>> modification of the uBITX, then goes on to show a new
>? ? ? ? ?design that
>? ? ? ? ?>> Farhan is working on.
>? ? ? ? ?>>
>? ? ? ? ?>> On Wed, Jun 2, 2021 at 4:30 AM Shirley Dulcey KE1L via
>? ? ? ? ?groups.io <> <
<>>
>? ? ? ? ?>> < <>
< <>>>
>? ? ? ? ?<mark@...
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>
>? ? ? ? ?>> <mailto:[email protected]
<mailto:[email protected]>
>? ? ? ? ?<mailto:[email protected]
<mailto:[email protected]>>>> wrote:
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ?The sBITX is a simple hybrid SDR; it uses
a conversion
>? ? ? ? ?to 27 MHz,
>? ? ? ? ?>>? ? ?a crystal filter there, and then downconversion to a
>? ? ? ? ?near-zero IF
>? ? ? ? ?>>? ? ?where the signal goes into an audio ADC.
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ?Here's a link to Farhan's talk about it at
>? ? ? ? ?>>? ? ?FDIM:?
<>
>? ? ? ? ?<
<>>
>? ? ? ? ?>>? ? ?<
<>
>? ? ? ? ?<
<>>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ?On Wed, Jun 2, 2021 at 2:07 AM Rafael Diniz
>? ? ? ? ?>>? ? ?<rafael@...
<mailto:rafael@...> <mailto:rafael@...
<mailto:rafael@...>>
>? ? ? ? ?<mailto:rafael@...
<mailto:rafael@...>
>? ? ? ? ?<mailto:rafael@...
<mailto:rafael@...>>>> wrote:
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?Hi everybody,
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?I'm sorry, but after many messages, I also wanna
>? ? ? ? ?know what
>? ? ? ? ?>>? ? ? ? ?sBITX is.
>? ? ? ? ?>>? ? ? ? ?This link does not give any
clue. Any link with the
>? ? ? ? ?actual
>? ? ? ? ?>>? ? ? ? ?video of
>? ? ? ? ?>>? ? ? ? ?Farhan speech?
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?Thanks,
>? ? ? ? ?>>? ? ? ? ?Rafael
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?On 6/1/21 8:41 PM, Jerry Gaffke via groups.io
<>
>? ? ? ? ?< <>>
>? ? ? ? ?>>? ? ? ? ?< <>
< <>>> wrote:
>? ? ? ? ?>>? ? ? ? ?> See?
?/g/BITX20/topic/82011726
</g/BITX20/topic/82011726>
>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>>
>? ? ? ? ?>>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>
>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>>>
>? ? ? ? ?>>? ? ? ? ?> </g/BITX20/topic/82011726
</g/BITX20/topic/82011726>
>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>>
>? ? ? ? ?>>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>
>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>>>>
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>? ? ? ? ?> On Tue, Jun 1, 2021 at 08:42 AM, allen west
wrote:
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>? ? ? ? ?>? ? ?I guess I have not been following as
closely as I
>? ? ? ? ?>>? ? ? ? ?should.? But
>? ? ? ? ?>>? ? ? ? ?>? ? ?what is this sBITX?? When I joined this
group
>? ? ? ? ?it was for
>? ? ? ? ?>>? ? ? ? ?the BITX
>? ? ? ? ?>>? ? ? ? ?>? ? ?20, 40
or the uBITX. ?
>? ? ? ? ?>>? ? ? ? ?>? ? ??
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>
>? ? ? ? ?>
>? ? ? ? ?>
>? ? ? ? ?>
>? ? ? ? ?>
>
>
>
>
>
>
>
|
It is too early to think about that. The sbitx is an add-on for existing radios with a little bit of modification to the crystal filter. I am designing a new radio to go with it.? But, the ubitx, as a product, will continue as an all analog radio. - f
On Fri, Jun 4, 2021 at 11:15 AM Rafael Diniz < rafael@...> wrote: Dear Farhan,
Do you plan to "deploy" sBITX as uBitx, with pre-assembled selling and
so on?
Thanks,
Rafael Diniz
On 6/2/21 5:01 PM, Ashhar Farhan wrote:
> Oops, I send to the wrong?email addy. Sorry about that. this was meant
> for Bill.
> - f
>
> On Wed, Jun 2, 2021 at 7:28 PM Ashhar Farhan via
> <> <farhanbox=[email protected]
> <mailto:[email protected]>> wrote:
>
>? ? ?Bill,
>? ? ?The only time I used gilbert cell (NE602) was to build the 21 MHz
>? ? ?to 29 MHz transponder. The nearest station would be at least 500
>? ? ?KM away and the Yagis of the bad boys would be pointing along the
>? ? ?ground towards each other. Isn't it an active mixer?
>? ? ?The KISS mixer is a passive mixer. The FETs are used as switches,
>? ? ?not as amplifiers. The big deal is this: In a diode mixer, the
>? ? ?diodes are turned on by the switching current that flows along
>? ? ?with signal current through the same paths. In the FET switching
>? ? ?mixer, there is no switching current, and the switch is turned on
>? ? ?by driving the gate very hard and almost instantaneously - that
>? ? ?makes it so resilient?to any reflected current coming back from
>? ? ?the filter side.?
>? ? ?SDR aside, the KISS mixer, theoretically consumes zero drive
>? ? ?power. It just needs a square-wave voltage to switch. It makes for
>? ? ?a great analog front-end. That's what I tried with the Minima, I
>? ? ?should have used multiple band pass filters and added CW and AGC,
>? ? ?it would have made a great radio. I might still do that!
>? ? ?I just got a strip of 100 40 MHz, fundamental crystals. Let me see
>? ? ?if I can hammer out a filter with them. If it works, then I can
>? ? ?extend the sBITX to full 30 Mhz coverage.
>? ? ?I must read up on the Gilbert cell, EMRFD has devoted quite a few
>? ? ?pages to it.
>? ? ?- f
>
>? ? ?On Wed, Jun 2, 2021 at 3:22 PM Rafael Diniz
>? ? ?<rafael@... <mailto:rafael@...>> wrote:
>
>? ? ? ? ?One question: Which is the transmit and receive bandwidth of
>? ? ? ? ?the sBITX?
>
>? ? ? ? ?How to buy or build one? (Without the Raspberry Pi, as the
>? ? ? ? ?need for
>? ? ? ? ?processing I have is much higher of what the Raspberry can
>? ? ? ? ?provide - I
>? ? ? ? ?need at least AVX2 4th gen Intel chip for ML purposes).
>
>? ? ? ? ?Thanks,
>? ? ? ? ?Rafael Diniz
>
>? ? ? ? ?On 6/2/21 12:04 PM, Rafael Diniz wrote:
>? ? ? ? ?> Thanks a lot!
>? ? ? ? ?>
>? ? ? ? ?> Reading the names of Farhan and Phil Karn makes me shiver! Wow!!
>? ? ? ? ?>
>? ? ? ? ?> You are the ones!!!
>? ? ? ? ?>
>? ? ? ? ?> Rafael
>? ? ? ? ?>
>? ? ? ? ?> On 6/2/21 11:32 AM, Shirley Dulcey KE1L wrote:
>? ? ? ? ?>> I should?add that it's a transceiver design, not just a
>? ? ? ? ?receiver.
>? ? ? ? ?The
>? ? ? ? ?>> DSP is done by a Raspberry Pi 4. The talk first presents a
>? ? ? ? ?>> modification of the uBITX, then goes on to show a new
>? ? ? ? ?design that
>? ? ? ? ?>> Farhan is working on.
>? ? ? ? ?>>
>? ? ? ? ?>> On Wed, Jun 2, 2021 at 4:30 AM Shirley Dulcey KE1L via
>? ? ? ? ? <>
>? ? ? ? ?>> < <>>
>? ? ? ? ?<mark=[email protected] <mailto:[email protected]>
>? ? ? ? ?>> <mailto:[email protected]
>? ? ? ? ?<mailto:[email protected]>>> wrote:
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ?The sBITX is a simple hybrid SDR; it uses
a conversion
>? ? ? ? ?to 27 MHz,
>? ? ? ? ?>>? ? ?a crystal filter there, and then downconversion to a
>? ? ? ? ?near-zero IF
>? ? ? ? ?>>? ? ?where the signal goes into an audio ADC.
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ?Here's a link to Farhan's talk about it at
>? ? ? ? ?>>? ? ?FDIM:?
>? ? ? ? ?<>
>? ? ? ? ?>>? ? ?<
>? ? ? ? ?<>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ?On Wed, Jun 2, 2021 at 2:07 AM Rafael Diniz
>? ? ? ? ?>>? ? ?<rafael@... <mailto:rafael@...>
>? ? ? ? ?<mailto:rafael@...
>? ? ? ? ?<mailto:rafael@...>>> wrote:
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?Hi everybody,
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?I'm sorry, but after many messages, I also wanna
>? ? ? ? ?know what
>? ? ? ? ?>>? ? ? ? ?sBITX is.
>? ? ? ? ?>>? ? ? ? ?This link does not give any
clue. Any link with the
>? ? ? ? ?actual
>? ? ? ? ?>>? ? ? ? ?video of
>? ? ? ? ?>>? ? ? ? ?Farhan speech?
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?Thanks,
>? ? ? ? ?>>? ? ? ? ?Rafael
>? ? ? ? ?>>
>? ? ? ? ?>>? ? ? ? ?On 6/1/21 8:41 PM, Jerry Gaffke via
>? ? ? ? ?<>
>? ? ? ? ?>>? ? ? ? ?< <>> wrote:
>? ? ? ? ?>>? ? ? ? ?> See? ?/g/BITX20/topic/82011726
>? ? ? ? ?</g/BITX20/topic/82011726>
>? ? ? ? ?>>? ? ? ? ?</g/BITX20/topic/82011726
>? ? ? ? ?</g/BITX20/topic/82011726>>
>? ? ? ? ?>>? ? ? ? ?> </g/BITX20/topic/82011726
>? ? ? ? ?</g/BITX20/topic/82011726>
>? ? ? ? ?>>? ? ? ? ?</g/BITX20/topic/82011726
>? ? ? ? ?</g/BITX20/topic/82011726>>>
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>? ? ? ? ?> On Tue, Jun 1, 2021 at 08:42 AM, allen west wrote:
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>? ? ? ? ?>? ? ?I guess I have not been following as closely as I
>? ? ? ? ?>>? ? ? ? ?should.? But
>? ? ? ? ?>>? ? ? ? ?>? ? ?what is this sBITX?? When I joined this group
>? ? ? ? ?it was for
>? ? ? ? ?>>? ? ? ? ?the BITX
>? ? ? ? ?>>? ? ? ? ?>? ? ?20, 40
or the uBITX. ?
>? ? ? ? ?>>? ? ? ? ?>? ? ??
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>? ? ? ? ?>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>>
>? ? ? ? ?>
>? ? ? ? ?>
>? ? ? ? ?>
>? ? ? ? ?>
>? ? ? ? ?>
>
>
>
>
>
>
>
|
Dear Farhan, Do you plan to "deploy" sBITX as uBitx, with pre-assembled selling and so on? Thanks, Rafael Diniz On 6/2/21 5:01 PM, Ashhar Farhan wrote: Oops, I send to the wrong?email addy. Sorry about that. this was meant
for Bill.
- f
On Wed, Jun 2, 2021 at 7:28 PM Ashhar Farhan via groups.io
<> <farhanbox@...
<mailto:[email protected]>> wrote:
Bill,
The only time I used gilbert cell (NE602) was to build the 21 MHz
to 29 MHz transponder. The nearest station would be at least 500
KM away and the Yagis of the bad boys would be pointing along the
ground towards each other. Isn't it an active mixer?
The KISS mixer is a passive mixer. The FETs are used as switches,
not as amplifiers. The big deal is this: In a diode mixer, the
diodes are turned on by the switching current that flows along
with signal current through the same paths. In the FET switching
mixer, there is no switching current, and the switch is turned on
by driving the gate very hard and almost instantaneously - that
makes it so resilient?to any reflected current coming back from
the filter side.?
SDR aside, the KISS mixer, theoretically consumes zero drive
power. It just needs a square-wave voltage to switch. It makes for
a great analog front-end. That's what I tried with the Minima, I
should have used multiple band pass filters and added CW and AGC,
it would have made a great radio. I might still do that!
I just got a strip of 100 40 MHz, fundamental crystals. Let me see
if I can hammer out a filter with them. If it works, then I can
extend the sBITX to full 30 Mhz coverage.
I must read up on the Gilbert cell, EMRFD has devoted quite a few
pages to it.
- f
On Wed, Jun 2, 2021 at 3:22 PM Rafael Diniz
<rafael@... <mailto:rafael@...>> wrote:
One question: Which is the transmit and receive bandwidth of
the sBITX?
How to buy or build one? (Without the Raspberry Pi, as the
need for
processing I have is much higher of what the Raspberry can
provide - I
need at least AVX2 4th gen Intel chip for ML purposes).
Thanks,
Rafael Diniz
On 6/2/21 12:04 PM, Rafael Diniz wrote:
> Thanks a lot!
>
> Reading the names of Farhan and Phil Karn makes me shiver! Wow!!
>
> You are the ones!!!
>
> Rafael
>
> On 6/2/21 11:32 AM, Shirley Dulcey KE1L wrote:
>> I should?add that it's a transceiver design, not just a
receiver.
The
>> DSP is done by a Raspberry Pi 4. The talk first presents a
>> modification of the uBITX, then goes on to show a new
design that
>> Farhan is working on.
>>
>> On Wed, Jun 2, 2021 at 4:30 AM Shirley Dulcey KE1L via
groups.io <>
>> < <>>
<mark@... <mailto:[email protected]>
>> <mailto:[email protected]
<mailto:[email protected]>>> wrote:
>>
>>? ? ?The sBITX is a simple hybrid SDR; it uses a conversion to 27 MHz,
>>? ? ?a crystal filter there, and then downconversion to a
near-zero IF
>>? ? ?where the signal goes into an audio ADC.
>>
>>? ? ?Here's a link to Farhan's talk about it at
>>? ? ?FDIM:?
<>
>>? ? ?<
<>>
>>
>>
>>? ? ?On Wed, Jun 2, 2021 at 2:07 AM Rafael Diniz
>>? ? ?<rafael@... <mailto:rafael@...>
<mailto:rafael@...
<mailto:rafael@...>>> wrote:
>>
>>? ? ? ? ?Hi everybody,
>>
>>? ? ? ? ?I'm sorry, but after many messages, I also wanna
know what
>>? ? ? ? ?sBITX is.
>>? ? ? ? ?This link does not give any clue. Any link with the actual
>>? ? ? ? ?video of
>>? ? ? ? ?Farhan speech?
>>
>>? ? ? ? ?Thanks,
>>? ? ? ? ?Rafael
>>
>>? ? ? ? ?On 6/1/21 8:41 PM, Jerry Gaffke via groups.io
<>
>>? ? ? ? ?< <>> wrote:
>>? ? ? ? ?> See? ?/g/BITX20/topic/82011726
</g/BITX20/topic/82011726>
>>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>>
>>? ? ? ? ?> </g/BITX20/topic/82011726
</g/BITX20/topic/82011726>
>>? ? ? ? ?</g/BITX20/topic/82011726
</g/BITX20/topic/82011726>>>
>>? ? ? ? ?>
>>? ? ? ? ?> On Tue, Jun 1, 2021 at 08:42 AM, allen west wrote:
>>? ? ? ? ?>
>>? ? ? ? ?>? ? ?I guess I have not been following as closely as I
>>? ? ? ? ?should.? But
>>? ? ? ? ?>? ? ?what is this sBITX?? When I joined this group
it was for
>>? ? ? ? ?the BITX
>>? ? ? ? ?>? ? ?20, 40 or the uBITX. ? >>? ? ? ? ?>? ? ??
>>? ? ? ? ?>
>>? ? ? ? ?>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
|
where was the list tom
dave k7da
On 6/3/2021 8:05 AM, Tom, wb6b wrote:
toggle quoted message
Show quoted text
On Tue, Jun 1, 2021 at 07:29 AM, Ashhar Farhan wrote:
I thought hard about current consumption. "We are no
longer in Kansas".
I saw an article a little while back. The article was a
comprehensive list of reference sites, articles, books and data
that you should clone onto a Raspberry Pi and place in a sealed
metal box, so if an apocalypse?happens you have everything you
need for reference to start over again. (I suppose you should put
a keyboard, some kind of display and versatile power source in
there, too.)
This could be a good idea if you are operating from a remote
mountain top to use a Raspberry Pi to control your radio so you
have everything you need information wise should things go bad
while while you are away from civilization. :)
Tom, wb6b
|
Re: Receiver working, sensitivity issues?
my 170m loop is made from 3mm antenna wire ... a thin wire from a
tvset wont work
dg9bfc sigi
Am 04.06.2021 um 04:32 schrieb masch57:
toggle quoted message
Show quoted text
Wire, yes, and don't be picky about it.? Old CRT TVs or monitors
have deflection coils with lots of thin wire that is free and
nearly invisible.? Push it through the screen in your window and
far out into the world.? Then scrape the end of it (it's covered
in enamel) and hook it up to one terminal of your antenna
connector.? Hook up the other terminal to a ground, or just more
wire, going somewhere else.? Try different stuff.? Did this as a
kid, still doing now, and even transmitting on it using a cheap
antenna tuner.
|
Re: Receiver working, sensitivity issues?
Wire, yes, and don't be picky about it.? Old CRT TVs or monitors have deflection coils with lots of thin wire that is free and nearly invisible.? Push it through the screen in your window and far out into the world.? Then scrape the end of it (it's covered in enamel) and hook it up to one terminal of your antenna connector.? Hook up the other terminal to a ground, or just more wire, going somewhere else.? Try different stuff.? Did this as a kid, still doing now, and even transmitting on it using a cheap antenna tuner.
|
Re: Receiver working, sensitivity issues?
hight is might ... and an elmer once said to me if you can not
make it high then make it long :-)
dg9bfc sigi
(allday aerial is a 170m lopp 10m agl)
Am 04.06.2021 um 03:56 schrieb Gordon
Gibby:
toggle quoted message
Show quoted text
I¡¯m actually amazed that you are doing as well as you are. ? There
is a concept called ¡°aperture¡±that relates to the volume of space
from which a given antenna extracts signal
If you have more aperture, you have more signal captured. A 1
m loop I think will have a very small aperture
Luckily at home frequencies, we work with signals that are
not at the very bottom of the capabilities of most receivers.
That¡¯s because the background noise just from the galaxies
lightning storms etc., is considerable.
However you face the additional hindrance that you have
buildings around you and those absorb power from incoming
signals that have to pass through them based on their geometry.
?If the only clear sky you can see is directly above you, then
only signals that come in from that angle will be unhindered
Wise person has said that the best antenna is to get ¡°as much
wire as you can, as high as you can, and then match to whatever
its impedance is.¡±
I thought that was worth remembering!
It might give you further ideas.
Gordon Kx4z?
On Jun 3, 2021, at 21:33, Curt via
groups.io <wb8yyy@...> wrote:
?Simran
For receive try stretching out 8m or more of wire. The ubitx
was optimized? for full sized antennas, but 8m or more
should bring some signals.?
Patiently learn about ham radio antennas. To get RF across
coax with minimum loss, the antenna needs to be nearly
matched. The EFHW was mentioned, it uses a special network
to feed it at one end. Read resources on the web and watch
video on basic antenna theory.?
Maybe your nation is very much still in pandemic, use the
time to learn. Meanwhile use whatever wire you have to
hopefully grab some signals.? Use headphones then the
signals should be louder.?
Glad to have you joining global ham radio.?
Curt wb8yyy
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Re: Receiver working, sensitivity issues?
I¡¯m actually amazed that you are doing as well as you are. ? There is a concept called ¡°aperture¡±that relates to the volume of space from which a given antenna extracts signal
If you have more aperture, you have more signal captured. A 1 m loop I think will have a very small aperture
Luckily at home frequencies, we work with signals that are not at the very bottom of the capabilities of most receivers. That¡¯s because the background noise just from the galaxies lightning storms etc., is considerable.
However you face the additional hindrance that you have buildings around you and those absorb power from incoming signals that have to pass through them based on their geometry. ?If the only clear sky you can see is directly above you, then only signals that come in from that angle will be unhindered
Wise person has said that the best antenna is to get ¡°as much wire as you can, as high as you can, and then match to whatever its impedance is.¡±
I thought that was worth remembering! It might give you further ideas.
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On Jun 3, 2021, at 21:33, Curt via groups.io <wb8yyy@...> wrote:
?Simran
For receive try stretching out 8m or more of wire. The ubitx was optimized? for full sized antennas, but 8m or more should bring some signals.?
Patiently learn about ham radio antennas. To get RF across coax with minimum loss, the antenna needs to be nearly matched. The EFHW was mentioned, it uses a special network to feed it at one end. Read resources on the web and watch video on basic antenna theory.?
Maybe your nation is very much still in pandemic, use the time to learn. Meanwhile use whatever wire you have to hopefully grab some signals.? Use headphones then the signals should be louder.?
Glad to have you joining global ham radio.?
Curt wb8yyy
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Re: Receiver working, sensitivity issues?
Simran
For receive try stretching out 8m or more of wire. The ubitx was optimized? for full sized antennas, but 8m or more should bring some signals.?
Patiently learn about ham radio antennas. To get RF across coax with minimum loss, the antenna needs to be nearly matched. The EFHW was mentioned, it uses a special network to feed it at one end. Read resources on the web and watch video on basic antenna theory.?
Maybe your nation is very much still in pandemic, use the time to learn. Meanwhile use whatever wire you have to hopefully grab some signals.? Use headphones then the signals should be louder.?
Glad to have you joining global ham radio.?
Curt wb8yyy
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Re: Cheap Chinese Linear LPF
Hi Tom,
Are you familiar with the Youtube channel "Applied Science"? The engineer who runs it has some interesting videos:
"Shooting an electron beam through air"
He builds a vacuum chamber with a precision exit beam hole and uses a crushed low voltage lamp (flashlight bulb size) as a heated cathode to generate the electrons.
I also like the one where he builds a water jet that can cut aluminum using parts from a $130 Sun Joe pressure washer. And a scanning electron microscope, and some homebrew xray projects.
11 years of projects in all.
Ted KX4OM
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Re: Receiver working, sensitivity issues?
You might look at the SOTABeams web site.? They often use an
EFHW.
Gerry
Sent by the Thunderbird
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Hello Arv thanks for the reply. I will certainly try to first
procure the caps and build aswell once the setup is done with
formally mfg caps.
There is this group on FaceBook called as Minimalist QRP? and a
poster named Billy Cheung has done phenomenal work by 3d Printing
Capacitors.
It's very inspirational too.
Thanks for the links.
In the meanwhile, What are you guys suggesting when it comes to
inverted V Antenna. There is a mango tree right in front of my
house. I can surely do something with it.
Any leads with plans w.r.t inverted V would be of great help!
Thanks
Rgds
Simran
P.S My call sign is yet to be assigned to me... things are going
at a snails pace with the government department. :(
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Re: Receiver working, sensitivity issues?
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Hello Arv thanks for the reply. I will certainly try to first procure the caps and build aswell once the setup is done with formally mfg caps.
There is this group on FaceBook called as Minimalist QRP? and a poster named Billy Cheung has done phenomenal work by 3d Printing Capacitors.
It's very inspirational too.
Thanks for the links.
In the meanwhile, What are you guys suggesting when it comes to inverted V Antenna. There is a mango tree right in front of my house. I can surely do something with it.
Any leads with plans w.r.t inverted V would be of great help!
Thanks
Rgds
Simran
P.S My call sign is yet to be assigned to me... things are going at a snails pace with the government department. :(
?
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?
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Re: Receiver working, sensitivity issues?
Hello Arv thanks for the reply. I will certainly try to first procure the caps and build aswell once the setup is done with formally mfg caps. There is this group on FaceBook called as Minimalist QRP? and a poster named Billy Cheung has done phenomenal work by 3d Printing Capacitors. It's very inspirational too. Thanks for the links. In the meanwhile, What are you guys suggesting when it comes to inverted V Antenna. There is a mango tree right in front of my house. I can surely do something with it. Any leads with plans w.r.t inverted V would be of great help! Thanks Rgds Simran P.S My call sign is yet to be assigned to me... things are going at a snails pace with the government department. :(
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Re: Receiver working, sensitivity issues?
Simran
You can make your own variable capacitor from insulators and conductors.
Formulas are available for calculating the amount of capacitance from size
of plates and dielectric constant of the insulators.
Capacitor insulators can be made from thin plastic from the sides of 2 liter
soft drink bottles.?
Capacitor plates can be made from almost any conductive metal, but copper
sheet or aluminium sheet would be best.
The layout can have the plates rotate from the center (half circle plates) or
by having them rotate from one corner (rectangular plates).
Arv _-_
Hello Will, thanks for the reply.
The loop that I made was by taking a string...hooking it to one of the leg of a chair... measuring 1Meter length and exactly placing a marker pen at the end of 1 meter.
Drew an arc over a wooden plank and managed to make a guide along the arc created. An aluminum pipe of 10mm was put via the guide and the hollow aluminum tube was rolled.
I will look out for a capacitor. I would also like to experiment with other kinds of antenna which i can place on the ground floor itself.
Let me know what worked best for you guys.
rgds
Simran
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I just got handed (about 5 hours ago)? a goodly length (about 7.3 meters) of 50 millimeter Heliax.? It's a bit big for a transmission line for the uBITX (LOL), but I also have a 5-500 pf 5Kv ITT-Jennings vacuum variable with a motor drive and limit switches.? Guess who will be building and using a magnetic loop! According to a loop calculator spreadsheet made up by AA5TB, i should be able to cover most of the HF range.
Gerry, VE4GKS
Sent by the Thunderbird
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Re: Receiver working, sensitivity issues?
Hello Will, thanks for the reply.
The loop that I made was by taking a string...hooking it to one of the leg of a chair... measuring 1Meter length and exactly placing a marker pen at the end of 1 meter.
Drew an arc over a wooden plank and managed to make a guide along the arc created. An aluminum pipe of 10mm was put via the guide and the hollow aluminum tube was rolled.
I will look out for a capacitor. I would also like to experiment with other kinds of antenna which i can place on the ground floor itself.
Let me know what worked best for you guys.
rgds
Simran
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Re: Receiver working, sensitivity issues?
Hi Simran! :-)
I have used loop antennas in the past, and if they aren't tuned well, they can be almost deaf.? If you can, try to get a tuning capacitor for the loop as soon as you can, which will help dramatically, at least in my own experiences.?
I have seen that people use a large value variable capacitor (200 or more pF) for 'rough' tuning, then also use a smaller value variable cap for fine-tuning.? Variable capacitors are not easy to find, but they are out there.? I often have to purchase old stereos, clock radios and the like to grab the variable caps from them.? I've only used one (large value) variable capacitor for my loops, and that was just fine for good receiving.? Just know that they are very touchy!
I'm sure more experienced / more intelligent folks will answer here, but those are my meager suggestions.
Blessings and 73!
Will B
AF7EC
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Receiver working, sensitivity issues?
Hi, I am able to rx a few stations locally
Got to hear someone speaking from about 1400km away on 20 Meters.
However, the issue is the signals that I get are pretty weak. I am using a homemade 1meter diameter loop antenna without any BalUn or tuning capacitor.
Currently, I don't have any VNA to gauge the antenna response. (Looking forward to getting Nano VNA...any other recommendations would do)
At times the signals are rising in amplitude and falling in amplitude (?fading?)
I live on the ground floor of an 8floored building. The terrace is about 100-120Feet from my house. The building is surrounded by other buildings, however ever there is a visible sky.
I took my rig to the terrace and still the signals are weak! I could hear someone from Mumbai locally talking to someone else. Only one-sided communication was rxd ie the local ham speaking which itself was weak.....
Tried adjusting the VFO and BFO....the audio was clear but weak.... a lot of static noise.
What would be the best way to go about understanding what is wrong here and where should I start from?
rgds
Simran
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Scratch building of the early version described in this group was encouraged: ? ?? /g/HBTE/messages?expanded=1Just search for "tinysa". It has since moved to production with significant enhancements. And is well worth $54.95 ? ?? Jerry, KE7ER
On Thu, Jun 3, 2021 at 07:52 AM, John Cunliffe W7ZQ wrote:
On Mon, Jan 11, 2021 at 12:55 PM, Jerry Gaffke wrote:
t's all open source, cloning is acceptable to do.
Sorry, the TinySA is not open source.?
John
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