Date   

Re: AE7EU Top Level PCB Mod

Diver Martin <diver.martin@...>
 

This is one of those "We'll see how this works" things I think.  The guy who I've been talking to knows his stuff pretty well when it comes to building radios, so I trust his advice.  He's got some cool stuff on his webpage, though he doesn't sell any of the kits anymore I think.... http://www.gridtoys.com.

On Fri, Jan 12, 2018 at 10:26 PM, Vince Vielhaber <vev@...> wrote:


On 01/13/2018 12:56 AM, Jerry Gaffke via Groups.Io wrote:
A neat trick, I've never seen a mixer used as an attenuator.
Though might be cheaper ways than using an ADE-1
And I'm curious how linear this would be for incoming high level RF signals
when partially attenuated.

Amplifier Research Model 777 is an RF leveling preamp.  It uses a mini-circuits mixer as an attenuator.  First time I saw one used for that. I had to modify one to smooth the output.  It was in the chain between an RF generator and an amplifier putting RF into an anechoic chamber.  Before smoothing, at moderately high RF fields the RF was setting off the Halon alarm!

Vince.
--
  Michigan VHF Corp.   http://www.nobucks.net/   http://www.CDupe.com/
                          http://www.metalworkingfun.com






--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?


Re: AE7EU Top Level PCB Mod

Vince Vielhaber
 

On 01/13/2018 12:56 AM, Jerry Gaffke via Groups.Io wrote:
A neat trick, I've never seen a mixer used as an attenuator.
Though might be cheaper ways than using an ADE-1
And I'm curious how linear this would be for incoming high level RF signals
when partially attenuated.
Amplifier Research Model 777 is an RF leveling preamp. It uses a mini-circuits mixer as an attenuator. First time I saw one used for that. I had to modify one to smooth the output. It was in the chain between an RF generator and an amplifier putting RF into an anechoic chamber. Before smoothing, at moderately high RF fields the RF was setting off the Halon alarm!

Vince.
--
Michigan VHF Corp. http://www.nobucks.net/ http://www.CDupe.com/
http://www.metalworkingfun.com


Re: MAX9814 integration to uBitX

Guy N7BIR <sgbridge@...>
 

Dave,

just received my Max9814 and was waiting for someone smarter than me to figure out the wiring to the uBITX. I did download the 9814 tutorial from Adafruit but haven’t read it yet. 


Re: AE7EU Top Level PCB Mod

Jerry Gaffke
 

Here's his board design, ADE-1 is bottom-right of the first sheet:
    https://groups.io/g/BITX20/attachment/38900/1/uBitx_top.pdf

Here's the ADE-1 datasheet:  
    https://www.minicircuits.com/pdfs/ADE-1.pdf

ADE-1 pins are as follows:
L=LO       (local oscillator, or vfo)
R=RFIN   (input from antenna, we assume this is a receiver)
I=RFOUT (intermediate frequency)

A current source on the I pin (RFOUT) will flow through the top-left and bottom-right diodes,
With those two diodes conducting, the tops of the two transformers are connected together,
and the bottoms are also.

So the L and R windings are effectively coupled through the two back-to-back transformers.
Signals pass freely from ATT-IN to ATT-OUT when the diodes are conducting.

A neat trick, I've never seen a mixer used as an attenuator.
Though might be cheaper ways than using an ADE-1
And I'm curious how linear this would be for incoming high level RF signals
when partially attenuated.

Jerry, KE7ER


On Fri, Jan 12, 2018 at 09:21 pm, Mike Woods wrote:
Ok - I understand how it works now.  The one remaining question is how injecting DC into the output side (IF pin) of the mixer (as you have it drawn) would unbalance the mixer? Doesn’t this look like a short circuit to the DC? I would have thought you would connect the DC to the LO input to have current flowing through the diodes?
 


Re: AE7EU Top Level PCB Mod

 

Also, why not a whole kit option? would that not cut cost?


Re: AE7EU Top Level PCB Mod

 

I say make a Kickstarter or indigogo. I think more people might be interested in this. I for one would be happy to have all this in one board solving many mods at once. Not to mention an ATU in the bitx just sounds fun!

 

 73

   David


Re: AE7EU Top Level PCB Mod

Diver Martin <diver.martin@...>
 

A reasonable idea. Main thing will be to have both pads close enough together for the 0603, but large enough to accommodate the 1206.  I've done 0603's across a 1206 pad, but it's a PITA, and not easy for fabrication certainly.  I'm sure many fab houses won't like putting an 0603 onto a universal pad though, it'll probably have a greater tendency to tombstone.

On Fri, Jan 12, 2018 at 9:19 PM, Glenn <glennp@...> wrote:
Maybe consider a 'special' footprint that will take any smd size from 0603 to 1206. Seems there is plenty of room, in the main, to do this.

glenn
vk3pe




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?


Re: AE7EU Top Level PCB Mod

Diver Martin <diver.martin@...>
 

Hi Mike,

Check out the datasheet for the ADE-1 here: https://www.minicircuits.com/pdfs/ADE-1.pdf .  Page 1, bottom right side for the electrical schematic, you'll see the "I" pin has a DC connection to the diodes and then to ground.  This will forward-bias two of the diodes, and reverse-bias the other two.  A current limiting resistor (R14 in this case) limits the current going through the diodes.  I picked 1.2k randomly, it might be 1k-100k, I'll have to play with it I'm sure.

On Fri, Jan 12, 2018 at 9:21 PM, Mike Woods <mhwoods@...> wrote:
Ok - I understand how it works now.  The one remaining question is how injecting DC into the output side (IF pin) of the mixer (as you have it drawn) would unbalance the mixer? Doesn’t this look like a short circuit to the DC? I would have thought you would connect the DC to the LO input to have current flowing through the diodes?

Mike 




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?


Re: AE7EU Top Level PCB Mod

Mike Woods
 

Ok - I understand how it works now.  The one remaining question is how injecting DC into the output side (IF pin) of the mixer (as you have it drawn) would unbalance the mixer? Doesn’t this look like a short circuit to the DC? I would have thought you would connect the DC to the LO input to have current flowing through the diodes?

Mike 


Re: AE7EU Top Level PCB Mod

Glenn
 

Maybe consider a 'special' footprint that will take any smd size from 0603 to 1206. Seems there is plenty of room, in the main, to do this.

glenn
vk3pe


Re: preorder question #ubitx

 

I ordered mine on Dec12 as a preorder.  I just recieved an email that mine has shipped via DHL and to expect it on Tuesday 

Aug
AG5AT


while Im impatiently waiting

K9WIS
 

I ordered a hand full of nano boards to learn more about programming the part and set up my development project..I got it all up and running in a few minutes. I ordered 3 boards for under $10 on ebay and got them in a couple of days.
I also have an SI5351A board from a previuos project..maybe I'll make my own radiouino while Im waiting.

Brian K9WIS


Re: AE7EU Top Level PCB Mod

Diver Martin <diver.martin@...>
 

So, without any major modifications to the pick structure of my design, here's what I got back from Macrofab (US based in TX).

As you can see in the attached, the raw PCB cost is about $95 a pop, in qty 100.  In qty 1000, this goes down to about $75.  This doesn't include any of the Through-hole components though, things like the Teensy32, potentiometers, inductors (in a kit like this, it'd be you-wind), power connectors, and they couldn't quote me the ADE-1 ($2.55).  In total, about $45 in parts not included in that.  This makes the overall PCB $140, not including shipping, or about $150 if you assume about $10 for shipping within the USA, $130 if there were preorders for 1000 (Sorry, I don't have $10k to lose in advance, let alone $100k)

Is it even still reasonable?



On Fri, Jan 12, 2018 at 2:43 PM, Martin Held <diver.martin@...> wrote:
I used a lot of 0603's and such.  Those are a large percent of the assembly cost.  I could go to 1206's pretty easily I think....  A lot of people don't like assembling 0603's.  The other option then might be change a bunch of the resistors to through hole, same for the caps.

A coworker who's used the same assembly house got $0.40 a part for 25 PCB's, at about 180 parts per PCB he said.  That would make the assembly cost about $60.

There are a few places where resistor/capacitor arrays might be applicable in this design, which can significantly reduce costs.

On Fri, Jan 12, 2018 at 2:09 PM, chris gress <Chrisg0wfh@...> wrote:
Could you just get the ic,s fitted make the rest home assembly would that help cut the costs chris

On 12 Jan 2018 21:57, "Diver Martin" <diver.martin@...> wrote:
So, good news, bad news.

Good news: I got a BoM together, defined all the parts, etc.
Bad news:  The BoM (majority single unit pricing from Digikey, but I took out gross single-part costs like 0603 capacitors/resistors/etc) is $112.  This might vary from half to 3/4 depending on the volume, so $60 to $90 or something.  Without knowing the volumes I'd do, it's hard to define.
Good news:  I have a vendor in town that will assemble the boards.
Bad news:  It's about $1 a part to place it on the PCB in a prototype run.  There are 147 SMT parts, assuming the person buying the board installs all TH components, toroids, etc.  That's $150 a PCB for assembly worst case.  In prototype quantities, I was told $1 per part (RoHS $1.20) (qty 1-10 boards).  Past assemblies I've heard down from $0.1 per part to $0.25 per part, so I'm not quite sure where to go on that front, as it's also volume dependant I believe.  I've put out a few pings to those I know who've gotten things built up for a better guestimate, but for now, I'll go with the pessimistic $1/part.

So... Assuming a good case of $75 for the BoM, $10 for the PCB, $15-$150 for assembly, $10 shipping, not including the $500 NRE or my initial builds (so tack on $10 there too assuming a run of 100 PCB's).  Soooo... $110 to $250 is the current price bracket that I've got, the major uncertainty in the cost of per-part placement / assembly.

#1 cost item:  Relays for the tuner and other things ($35)
#2 cost item:  Teensy3.2 ($20)
#3 cost item:  Minicircuits mixer ($3.15)
#4 cost item:  20-turn precision pots ($3 total, eliminate final design)

For those who wish to peruse...  A BoM is attached.


On Wed, Jan 10, 2018 at 10:39 PM, Martin Held <diver.martin@...> wrote:
So, I've finally got a rough draft of what I'm thinking for my uBitx top PCB mod.  Features at this point are:

No modifications required to uBitx board itself (not to say a 470uF anti-pop mod might be bad, or other things couldn't be done)
ATU: 7-inductor, 8-capacitor with Hi-Z/Lo-Z switch.
Selectable Power output (two power input connectors)
Brain transplant:  Teensy3.2 96MHz ARM processor
All connections on side edges - no wiring to enclosure
Front panel with pushbutton switches
DSP Audio (Via Teensy32, would require headphones or amplified speakers)
Solderless AGC modification (Attenuator at the front end switched in during RX)
Realtime clock (via Teensy32)
Linear amplifier control (just a reed relay on a 3.5mm header, sorry, not an RCA, but you could easily change it...)
Top side only construction (would make assembly cost lower)

BoM cost:  Probably way higher than it should be.  Needs optimization, and I still need to enter in costs.
Complexity:  Probably way more than it should be.
Layout:  An ugly mess of routing.  I can't say I like it, but the constraints I put on myself made it really hard to route.  There's lots of open areas to cross with lots of signals going all different directions.

Picture of the layout and schematic PDF attached, along with a 3D view.

I think the one modification that I still need to consider is a microphone preamp.  But, I have no flippin' clue where on the PCB I'd put the gain control knob!  Might have to be an internal potentiometer....

--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?



--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?



--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?


Re: Bitx40/Raduino - no power out

 

Another group member Bill found his Q13 dead.. so seems like something is killing them!

Raj


At 13/01/2018, you wrote:
Probably ok as is, though a bit of copper could make it happier.

Most failed q13's  here saw a nearby QRO transmitter, and that's only fixed by the back-to-back diodes.
I'm not aware of many that burn out due to too much power dissipation, and we may be under the wire on the spec.
But if it did burn out, I'd replace it with the leaded TO92 2n3904, as that can dissipate considerably more.

As an alternative, I think Raj once suggested soldering a second mmbt3904 on top of it.
Or I suppose you could solder a leaded 2n3904 in parallel.
The ubitx uses paralled 2n3904's in that position.

Your choice.


On Fri, Jan 12, 2018 at 02:59 pm, Gordon Gibby wrote:

should we glue some sort of small bit of copper on top of that hurtin' puppy?


Re: Bitx40/Raduino no power - help

 

Vic,

RV136 is DRIVE and not bias. Bias is RV1, please leave it alone for now and see suggestion below!

You may have a problem with soldering of L6 or L7 or the relay K2.

Raj

At 12/01/2018, you wrote:
More information on this problem: I adjusted RV136 bias and find I can adjust the overall current draw during transmit from 1.7a (fully CCW) down to 0.31a (roughly center of RV136 rotation, no further drop when fully CW) and there is no change when modulating. The supply voltage (14v) is seen on the PA heat sink tab, and the other pins measure 0v and 3.9v when transmitting. I can hear the undistorted modulation in a nearby receiver and I tried 2 different electret elements with identical results...no increase in current when modulating. Tried both into a dummy load and an antenna...no difference.

Any ideas or help with what is wrong here?

=Vic=


Re: preorder question #ubitx

Art Howard
 

I would suggest paying the extra $10 for DHL shipping

On 12 Jan 2018 2:06 pm, "Xcott Craver" <xcottcraver@...> wrote:
Hi,

The site still has a Buy page listing 109 as the price.  Is HFsignals still accepting orders at this price?  I understand everything's on preorder now, but I want to make sure that an order placed today will "go somewhere."

Thanks, Xcott K2CAJ


Re: Sotabeams CW filter problem

Bob Benedict, KD8CGH
 

Michael
  Thanks for the suggestions. I'll try the .1 uF cap first.
  The power is always on to my filter.
  The first time I wired it, I tied the AF filter output to the line to the audio connector. Big mistake. Even when there was no input to the AF filter it generates noise on it's output.
  I put the AF filter in between Vol-H and Vol-M in the audio chain. It's just before the TDA2822 amplifier. The rotary selects bypass, through filter with normal CW or through filter with narrow CW.
    Bob   KD8CGH


Re: uBITX Case

William Londree <ventura_bill@...>
 




Rearranged labels. Used bigger for Call Sign.


Re: Sotabeams CW filter problem

 

Bob : 

I successfully added the General Purpose SotaBeams DSP filter to my BITX40. I am still waiting on my uBitx so I am not yet familiar with the
wiring yet. Let me have a peek at the uBITX schematic and I'll get back to you over the weekend once I understand how you have wired it.

A couple of things that I found when I integrated the Sotabeams DSP filterwith the Bitx40. I had some very weird interactions with the volume control & LM386 audio amp until  I put a 0.1 uF coupling cap in series with the output of the DSP filter. I recommend that you do that for starters. 

The other thing I noticed is that the filter itself generates some hash, which it seems to conveniently filter out of the audio going through it.
With my wiring I did't have enough poles on the switch that I am using to control the power to the filter, so power is on even when I bypass the filter.
I fixed the hash problem by using VK3YEs trick of an RC filter in series with the power leads to the audio filter. It is two 220 uF electrolytics to ground with a 12 ohm series resistor between the + leads of the caps and it prevents internal noise generated by the filter from getting back along the supply leads into the rest of the rig.

Cheers

Michael VE3WMB 

P.S. Start with the coupling cap in series with the output of the filter and see if things improve. I will get back to you once I have looked at the schematic and 
figured out how you wired things up. 


Re: Max 9814

lostfrogsrecords <dave@...>
 

Thanks Mike, that looks great!  A lot of good work and documentation as well as PCB offering.

I'm going with a PCB assembly from Adafruit, and specifically to interface to the uBitX circuitry,

Dave, KI4PSR


On 1/12/2018 7:06 PM, Michael Hagen wrote:

 

Here is my mic with a MAX9814 speech processor in it.  I used the Mic and Sw supplied with BitX.

The PCB is tiny and fits up in the mic tube.  All parts were 3d Printed.

I have only tested it on the scope, the pot can adjust the output all the way to zero.

Testing showed constant output with 1-10mv signal from a generator.

I have provided a schematic.  It is basically made from an AP Note on the IC.

I also have a PCB in BitX that senses the PTT switch on the mic and activates Transmit.

This saves a wire to the Mic, and I can use standard 3.5 mm Stereo cord.   A 6 ft. double ended male was

0.99 at the 99 Cent store,  I cut it in half, making 2 cables.

I have a few PCBs.

73's

Mike, WA6ISP


On 1/3/2018 7:39 AM, Arvo KD9HLC via Groups.Io wrote:
A couple of people are looking at an Analog Devices SSM2167 chip on a board.

https://groups.io/g/BITX20/topic/6468223

I'm waiting for mine to come in.

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
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