On 2020-04-01, Phil Allison <pallison49@gmail.com> wrote:
Joerg wrote:
-------------
Up to about 30pf they'll likely remain. Skyworks and such. Those with
large capacitances lost their market.
** AM radio has disappeared ??
News to me.
No big problem, we can fix it in software
On Fri, 3 Apr 2020 09:51:14 -0000 (UTC), Jasen Betts
jasen@xnet.co.nz> wrote:
On 2020-04-01, Phil Allison <pallison49@gmail.com> wrote:
Joerg wrote:
-------------
Up to about 30pf they'll likely remain. Skyworks and such. Those with
large capacitances lost their market.
** AM radio has disappeared ??
News to me.
No big problem, we can fix it in software
A decent ARM, which typically includes a mediocre ADC, might, with a
PWM DAC for the audio, make a usable antenna-to-speaker AM receiver.
Could be a student project.
On 2020-04-03 10:32, jlarkin@highlandsniptechnology.com wrote:
On Fri, 3 Apr 2020 09:51:14 -0000 (UTC), Jasen Betts
jasen@xnet.co.nz> wrote:
On 2020-04-01, Phil Allison <pallison49@gmail.com> wrote:
Joerg wrote:
-------------
Up to about 30pf they'll likely remain. Skyworks and such. Those with
large capacitances lost their market.
** AM radio has disappeared ??
News to me.
No big problem, we can fix it in software
A decent ARM, which typically includes a mediocre ADC, might, with a
PWM DAC for the audio, make a usable antenna-to-speaker AM receiver.
Could be a student project.
A mediocre 10-bit ADC billed as 12-bit.
Cheers
Phil Hobbs
On Fri, 3 Apr 2020 18:35:44 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-04-03 10:32, jlarkin@highlandsniptechnology.com wrote:
On Fri, 3 Apr 2020 09:51:14 -0000 (UTC), Jasen Betts
jasen@xnet.co.nz> wrote:
On 2020-04-01, Phil Allison <pallison49@gmail.com> wrote:
Joerg wrote:
-------------
Up to about 30pf they'll likely remain. Skyworks and such. Those with
large capacitances lost their market.
** AM radio has disappeared ??
News to me.
No big problem, we can fix it in software
A decent ARM, which typically includes a mediocre ADC, might, with a
PWM DAC for the audio, make a usable antenna-to-speaker AM receiver.
Could be a student project.
A mediocre 10-bit ADC billed as 12-bit.
Still better than the terrible 1-volt ADCs in the Xilinx FPGAs.
Do tell!
On 2020-04-03 19:23, John Larkin wrote:
On Fri, 3 Apr 2020 18:35:44 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-04-03 10:32, jlarkin@highlandsniptechnology.com wrote:
On Fri, 3 Apr 2020 09:51:14 -0000 (UTC), Jasen Betts
jasen@xnet.co.nz> wrote:
On 2020-04-01, Phil Allison <pallison49@gmail.com> wrote:
Joerg wrote:
-------------
Up to about 30pf they'll likely remain. Skyworks and such. Those with
large capacitances lost their market.
** AM radio has disappeared ??
News to me.
No big problem, we can fix it in software
A decent ARM, which typically includes a mediocre ADC, might, with a
PWM DAC for the audio, make a usable antenna-to-speaker AM receiver.
Could be a student project.
A mediocre 10-bit ADC billed as 12-bit.
Still better than the terrible 1-volt ADCs in the Xilinx FPGAs.
Do tell!
Cheers
Phil Hobbs
On 2020-04-06 19:37, Clifford Heath wrote:
On 7/4/20 8:11 am, Phil Hobbs wrote:
On 2020-04-05 15:48, Joerg wrote:
On 2020-04-05 11:23, Ricky C wrote:
On Sunday, April 5, 2020 at 12:23:14 PM UTC-4, Phil Hobbs wrote:
On 2020-04-04 19:04, Joerg wrote:
On 2020-04-03 07:42, Phil Hobbs wrote:
On 2020-04-03 03:56, upsidedown@downunder.com wrote:
On Thu, 02 Apr 2020 16:21:17 -0700, Joerg
news@analogconsultants.com> wrote:
On 2020-04-01 17:29, Rick C wrote:
On Wednesday, April 1, 2020 at 7:31:01 PM UTC-4, Phil
Allison wrote:
Joerg wrote:
-------------
Up to about 30pf they'll likely remain. Skyworks and
such. Those with large capacitances lost their
market.
** AM radio has disappeared ??
News to me.
My car doesn't even receive AM, only FM, Sirius XM and
Slacker Internet radio.
I would not want that radio in my car. I listen to AM most
of the time when driving, and not just then.
.. Oh, and bluetooth from your phone. But no AM radio.
I think they could do that 100% in software if they
wanted to. It's only 1600 kHz max frequency.
Well, they don't go that far but everything is PLL or DDS
nowadays. There simply isn't a need any longer for large
capacitance varicaps to run the local oscillator. As for
the preselector (adjustable filter in front of the mixer),
that has fallen victim to the red pencil of the bean
counter, which has cost performance when in the vicinity of
other strong signals.
Selectivity ahead of the mixer was needed in the old days due
to mediocre mixers, usually a single transistor biased into
non-linearity. These mixers produced all kind of mixing
products, including images, mixing between all harmonics and
letting RF and LO frequencies through.
Using strong double balanced mixers (e.g diode rings), much
of the problems disappeared. By using a higher first IF, it
is also easy to get away with the image frequency response.
Thus, fixed tuned high pass filters below low end of the band
and low pass above the band is usually sufficient.
An arbitrarily strong mixer still needs selectivity to get rid
of the image frequency. SSB mixers help, but are a lot more
complicated than a tuned RF stage, and rarely have better than
30-40 dB rejection.
That's why many professional receivers have a very high IF, tens
of MHz and sometimes above 100MHz, then mix down straight to
455kHz or wherever one can buy the best filters.
In battery powered equipment, in which the power consumption
is the premium issue, very strong mixers can't be used, but
in car and mains powered receivers the use of strong high
power mixers is not a problem.
Not just that. With car radios every penny counts and I doubt
they will contain high-IP3 mixers. Probably not much more than a
glorified Gilbert cell in there.
Well, the TMUX1511 is only 40 cents in reels. I use them in
switched attenuators, and they're the greatest--2 pF C_off, 5 ohms
R_on. Almost like a relay.
When I looked for low resistance switches I found no shortage of low
voltage parts. ¹12 volt parts is a different matter. But 2 pF is
low.
If you ever need a really fine and well-matched low capacitance quad
switch check out the SD5400 series. Just keep in mind that ESD-wise
they are the princess on the pea. One wee sneeze ... phut ... gone.
The SD5400 series are the same technology as the Si8901, iirc.
Originally designed and made here in Sydney, I believe. Each time that
company invents something useful, the technology gets sold off by
selling the company minus the R&D, and the company is reborn under a
new name, so I can never remember the name(s). They've done it at
least four times though.
CH
And the people probably get to live somewhere where the beer is better
and the wildlife isn't all trying to kill them. A win all round.