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Page 3 of the Fairchild/OnSemi datasheet (page 4 in pdf reader), under Output Detector
says C4-6 is 15pf max, where pins 4 and 6 are source and drain of the output side optical FET they hide inside.
Could drive some other attenuator, we don't need to use the optical FET as the attenuator, if that's what you mean.
But at that point, I'm not sure why we don't just replace the H11F1M with a piece of wire.
Perhaps there's something special about the transfer characteristic?
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On Wed, Mar 28, 2018 at 04:55 pm, Sandy T wrote:
I might add that the 15pF is due to the LED which does have to be driven by the audio section second amplifier (with a current limited maximum of about 30mA). The FET Output (attenuation) can be elsewhere.
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Real hardware does not lie....I need to do some testing with real hardware which has now arrived from Mouser.
?
73 Kees K5BCQ
---------- Original Message ---------- From: "Jerry Gaffke via Groups.Io" <jgaffke@...> To: [email protected]Subject: Re: [BITX20] #bitx40 #ubitx Date: Wed, 28 Mar 2018 18:43:49 -0700 Page 3 of the Fairchild/OnSemi datasheet (page 4 in pdf reader), under Output Detector says C4-6 is 15pf max, where pins 4 and 6 are source and drain of the output side optical FET they hide inside. Could drive some other attenuator, we don't need to use the optical FET as the attenuator, if that's what you mean. But at that point, I'm not sure why we don't just replace the H11F1M with a piece of wire. Perhaps there's something special about the transfer characteristic? On Wed, Mar 28, 2018 at 04:55 pm, Sandy T wrote:
I might add that the 15pF is due to the LED which does have to be driven by the audio section second amplifier (with a current limited maximum of about 30mA). The FET Output (attenuation) can be elsewhere.
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The AD8367 is a nice part.
Can control gain with a Vctrl that is linear in dB.
Has 45dB of dynamic range.
Plus a square law detector.
Would be very nice in some applications, perhaps driving an ADC.
But that 45dB is from -2.5 to +42.5 dB of gain.
Would require major surgery of the uBitx to make use of 42.5 dB of RF gain,
the two BiDi amps have a total of about 32 dB, and that's it till the audio pre-amp.??
I suppose you could follow this part with a 40dB attenuator...
Mouser sells it for $10 in my kind of quantities,
though Analog Devices is (was?) fairly easy to get samples from.
Jerry
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On Wed, Mar 28, 2018 at 04:52 pm, K9HZ wrote:
Have a look at the AD8367¡? The circuit shown in the AP section I¡¯ve built and it works well into the VHF range.? Sorry, a whole $6
?
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If you want the attenuation in part of the RF/IF chain the part needs to go there to keep leads short. Use a shielded cable to hook up the control leads instead. Re: popping in the audio In the receiver I built a decade ago you could see the agc action delay between the audio increase and the IF agc action on an oscilloscope but I could never actually hear it in the speaker. I'm sure it was there but it also takes a speaker cone a little bit of time to move because of inertia in the cone itself and in the speaker motor. I suspect that helps damp out some of the initial popping on a strong signal. tim ab0wr On Wed, 28 Mar 2018 16:55:09 -0700 "Sandy T" <windy10605@...> wrote: I might add that the 15pF is due to the LED which does have to be
driven by the audio section second amplifier (with a current limited
maximum of about 30mA). The FET Output (attenuation) can be elsewhere.
73 Kees K5BCQ
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Speaking of real hardware, your Vector Impedance Analyzer kit at under $100
is the best deal I know of for anything of the sort.? ($10+4 for a bare board!)
Good to 150mhz, shows complex impedance with sign, plots smith charts, shows swr.
Great as an antenna analyzer, or just checking out a cap or coil across frequency.
Can be used as a two port Vector Network Analyzer.
? ??? ? ? ?(three kits up from the bottom)
A quick suggestion.? Perhaps someday when sales peter out,
sell the board with source or binary blob so we could use it with other ARM processors.
Good enough to just have the code return the complex impedance at each frequency step.
Could have something like a teensy instead of the Raduino on the uBitx, then have the option of?
including your VIA board, adapt it for use with whatever user interface and display we happen to have.
Jerry, KE7ER?
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On Wed, Mar 28, 2018 at 06:50 pm, Sandy T wrote:
Real hardware does not lie....I need to do some testing with real hardware which has now arrived from Mouser.
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I¡¯ll publish my circuit and the data shortly, although I doubt many people will want to build it.? I used an AD820 as the integrator/ filter/ RF gain by DC offset, and because it¡¯s so fast, the closed loop is stable and almost delay free.? No pops. Oh BTW you CAN use two 8367¡¯s in series to get >60db.? I have not tried that but may give it a shot just to see how well it works. ? I think we all have different goals with the uBITx.? I just want to use it to experiment to eventually have my own receiver design with all of the popular bells and whistles, that rivals the best commercial designs, yet is inexpensive.? In that respect, the uBITx is a great platform to start from and experiment with.? I¡¯ve been able to perfect a plethora of hardware add-ons that are directly transferrable to my final project.? I still have a little bit to do on my Auto Antenna tuner (and I still promise it will cost $35 or less), and I am playing with a DSP filter for the receiver that has an adjustable bandpass, center frequency and notch for $10 (sounds like and works just like my K3), ?Uses a Arduino too. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Yahoo Group. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Wednesday, March 28, 2018 9:40 PM
To: [email protected]
Subject: Re: [BITX20] #bitx40 #ubitx ? The AD8367 is a nice part.
Can control gain with a Vctrl that is linear in dB.
Has 45dB of dynamic range.
Plus a square law detector.
Would be very nice in some applications, perhaps driving an ADC.
But that 45dB is from -2.5 to +42.5 dB of gain.
Would require major surgery of the uBitx to make use of 42.5 dB of RF gain,
the two BiDi amps have a total of about 32 dB, and that's it till the audio pre-amp.??
I suppose you could follow this part with a 40dB attenuator...
Mouser sells it for $10 in my kind of quantities,
though Analog Devices is (was?) fairly easy to get samples from.
Jerry
On Wed, Mar 28, 2018 at 04:52 pm, K9HZ wrote: Have a look at the AD8367¡? The circuit shown in the AP section I¡¯ve built and it works well into the VHF range.? Sorry, a whole $6 ?
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Wow! Keep pushing the development! Sounds like I may need to get a larger case! The DSP sounds really interesting. tim ab0wr On Thu, 29 Mar 2018 00:01:50 -0500 "K9HZ" <bill@...> wrote: I¡¯ll publish my circuit and the data shortly, although I doubt many
people will want to build it. I used an AD820 as the integrator/
filter/ RF gain by DC offset, and because it¡¯s so fast, the closed
loop is stable and almost delay free. No pops. Oh BTW you CAN use
two 8367¡¯s in series to get >60db. I have not tried that but may
give it a shot just to see how well it works.
I think we all have different goals with the uBITx. I just want to
use it to experiment to eventually have my own receiver design with
all of the popular bells and whistles, that rivals the best
commercial designs, yet is inexpensive. In that respect, the uBITx
is a great platform to start from and experiment with. I¡¯ve been
able to perfect a plethora of hardware add-ons that are directly
transferrable to my final project. I still have a little bit to do
on my Auto Antenna tuner (and I still promise it will cost $35 or
less), and I am playing with a DSP filter for the receiver that has
an adjustable bandpass, center frequency and notch for $10 (sounds
like and works just like my K3), Uses a Arduino too.
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ
Owner - Operator
Big Signal Ranch ¨C K9ZC
Staunton, Illinois
Owner ¨C Operator
Villa Grand Piton ¨C J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com <>
Like us on Facebook! <>
Moderator ¨C North American QRO Yahoo Group.
email: <mailto:bill@...> bill@...
From: [email protected] [mailto:[email protected]] On Behalf Of Jerry
Gaffke via Groups.Io Sent: Wednesday, March 28, 2018 9:40 PM
To: [email protected]
Subject: Re: [BITX20] #bitx40 #ubitx
The AD8367 is a nice part.
Can control gain with a Vctrl that is linear in dB.
Has 45dB of dynamic range.
Plus a square law detector.
Would be very nice in some applications, perhaps driving an ADC.
But that 45dB is from -2.5 to +42.5 dB of gain.
Would require major surgery of the uBitx to make use of 42.5 dB of RF
gain, the two BiDi amps have a total of about 32 dB, and that's it
till the audio pre-amp. I suppose you could follow this part with a
40dB attenuator...
Mouser sells it for $10 in my kind of quantities,
though Analog Devices is (was?) fairly easy to get samples from.
Jerry
On Wed, Mar 28, 2018 at 04:52 pm, K9HZ wrote:
Have a look at the AD8367¡ The circuit shown in the AP section I¡¯ve
built and it works well into the VHF range. Sorry, a whole $6
---
This email has been checked for viruses by AVG.
|
Thanks for all the positive comments on the VIA, Jerry.? Milt Cram, W8NUE (of NUE-PSK Modem fame), has done an outstanding job on the firmware.? Sure is great to have guys like that in the group.
?
73 Kees K5BCQ??
---------- Original Message ---------- From: "Jerry Gaffke via Groups.Io" <jgaffke@...> To: [email protected]Subject: Re: [BITX20] #bitx40 #ubitx Date: Wed, 28 Mar 2018 20:05:44 -0700 Speaking of real hardware, your Vector Impedance Analyzer kit at under $100 is the best deal I know of for anything of the sort.? ($10+4 for a bare board!) Good to 150mhz, shows complex impedance with sign, plots smith charts, shows swr. Great as an antenna analyzer, or just checking out a cap or coil across frequency. Can be used as a two port Vector Network Analyzer. ? ??? ? ? ?(three kits up from the bottom) A quick suggestion.? Perhaps someday when sales peter out, sell the board with source or binary blob so we could use it with other ARM processors. Good enough to just have the code return the complex impedance at each frequency step. Could have something like a teensy instead of the Raduino on the uBitx, then have the option of? including your VIA board, adapt it for use with whatever user interface and display we happen to have. Jerry, KE7ER? On Wed, Mar 28, 2018 at 06:50 pm, Sandy T wrote:
Real hardware does not lie....I need to do some testing with real hardware which has now arrived from Mouser.
|
I, for one, am very interested in building it.?
If I am honest, I? am probably drawn to the uBitx more for the learning and experimental aspect than the out-of-the-box functionality of it.? Don't get me wrong, it's a wonderful radio out of the box, but the open source nature of it really appeals to me.? I have so? much to learn yet, and I can't think of a better way than constantly trying to tinker with a known good design.?
73,
Carl, K0MWC
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just to add to
Jerry's comments , the AQRP now extends considerably beyond
150 MHz too!
Bill, VK7MX
On 30/03/2018 1:56 AM, Sandy T wrote:
toggle quoted message
Show quoted text
Thanks for all the positive comments on the VIA, Jerry.? Milt
Cram, W8NUE (of NUE-PSK Modem fame), has done an outstanding job
on the firmware.? Sure is great to have guys like that in the
group.
?
73 Kees K5BCQ??
---------- Original Message ----------
From: "Jerry Gaffke via Groups.Io"
<jgaffke@...>
To: [email protected]
Subject: Re: [BITX20] #bitx40 #ubitx
Date: Wed, 28 Mar 2018 20:05:44 -0700
Speaking of real hardware, your Vector Impedance Analyzer kit at
under $100
is the best deal I know of for anything of the sort.? ($10+4 for
a bare board!)
Good to 150mhz, shows complex impedance with sign, plots smith
charts, shows swr.
Great as an antenna analyzer, or just checking out a cap or coil
across frequency.
Can be used as a two port Vector Network Analyzer.
? ???
? ? ?(three kits up from the bottom)
A quick suggestion.? Perhaps someday when sales peter out,
sell the board with source or binary blob so we could use it
with other ARM processors.
Good enough to just have the code return the complex impedance
at each frequency step.
Could have something like a teensy instead of the Raduino on the
uBitx, then have the option of?
including your VIA board, adapt it for use with whatever user
interface and display we happen to have.
Jerry, KE7ER?
On Wed, Mar 28, 2018 at 06:50 pm, Sandy T wrote:
Real hardware does not lie....I need to do some
testing with real hardware which has now arrived from Mouser.
|
K9HZ