Date   
Re: Designing Maritime Radio #bitx40

Jerry Gaffke
 

I could not see either picture on this chromebook.

You plan to be transmitting and receiving at a frequencies of 8.222 and 8.746mhz. 
The Bitx40 bandpass filter is used for both transmit and receive, so the simplest solution would
be to have a single bandpass filter using fixed components with a 500khz bandwidth.

Making this filter tunable during manufacture to properly align the rig may be a good idea
if the fixed parts are not precise enough to give the same center frequency for each rig built.
But this makes building and aligning rigs more complicated.

If you wind up using filters narrower than 500khz for some reason, it may be necessary to 
have one bandpass filter to transmit and one to receive, selected perhaps by relays.
A significant complication, best to avoid this.

Allowing the user to tune the filter seems unnecessary, as this will be operating on fixed
transmit and receive frequencies near 8mhz.

The transmit low pass filter can almost certainly be left about as it is with slight
adjustments made to inductor and capacitor values, no need for that to be tunable.
 


On Thu, Mar 1, 2018 at 03:59 pm, <qonita.salimah@...> wrote:
In this picture below, the Band Pass Filter is using a tunable inductor. But in the schematic files in hfsignals.com using a fixed inductor and capacitor.
Is there any advantage and disadvantage for these two types of passive components?

Re: full rig power control unit

K9HZ <bill@...>
 

I used DipTrace and I just uploaded the original file to the files section here under “K9HZ Projects’.  I believe KiCAD will also read DipTrace files (???) and you can make boards in that tool too.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Yahoo Group.

 

email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Walter
Sent: Thursday, March 1, 2018 6:33 AM
To: BITX20@groups.io
Subject: Re: [BITX20] full rig power control unit

 

If I wranted to build a circuit like this one is there a software to help me layout a perfboard for the circuit.  I have LTSpice but I don't see anything to layout a perf board in it. It just may be that I don't know where that feature is in the software.
--
73, W9KJO
Walter


Virus-free. www.avg.com

Re: full rig power control unit

K9HZ <bill@...>
 

No boards available… I designed it for a friend and as I said in my original post… it was prototyped and proven to work… but I had no desire to build boards (I want to finish the antenna tuner first).  If someone wants to provide boards, please, by all means do so… the circuit is public and for your use and modification.  I uploaded the DipTrace file I used to create the schematic to the “K9HZ Projects” files section here in the BIT20 Group.IO group.  I didn’t pay much attention to the part footprints because I just wanted a quick schematic… so beware that you need to check each part for its dimensions.  The actual part values are in the EXCEL spreadsheet that is in the files section as well…  So far it’s saved a couple of radios (or so it has been reported to me…).

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Yahoo Group.

 

email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Walter
Sent: Thursday, March 1, 2018 5:55 AM
To: BITX20@groups.io
Subject: Re: [BITX20] full rig power control unit

 

Is there a description and installation instructions for this mod?

Does someone actually have circuit boards that can be purchased for this?

--
73, W9KJO
Walter


Virus-free. www.avg.com

Re: full rig power control unit

Glenn
 

I only see one 62R resistor. I assume you mean that one is 68R ?   C10 & C11 are not in the bill of material.

Did you see my other post re the apparent reversal of the 'operate and fault' led's?

The reset switch does not reset the SCR's. Only the astable.

glenn
vk3pe

Re: Shipping notification

vk7hch@...
 

And on the 2nd of March, I have it in my hand. Ridiculous isn't it, 2 weeks for an eBay item from the next state, 4 days for an item from India!
Now the much anticipated fun begins!

Re: full rig power control unit

K9HZ <bill@...>
 

Parts list is the EXCEL file.  Watch the 68ohm resistor… you will have to adjust that for your applied voltage

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Yahoo Group.

 

email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of wb7dmx@...
Sent: Thursday, March 1, 2018 1:58 AM
To: BITX20@groups.io
Subject: Re: [BITX20] full rig power control unit

 

VERY GOOD THANKS

HOW ABOUT A PARTS LIST, NO VALUES IN PRINT


Virus-free. www.avg.com

Re: Where to from here?

Dave Bottom <ars.kd6az@...>
 

See Ian, KD8CECs blog and link to his firmware - turns it into a great radio 

Dave WI6R


On Mar 1, 2018, at 4:30 PM, davidaker@... wrote:

This afternoon, I drilled out my enclosure (one of the mailboxes from Lowes) and wired it up and made a contact on 30m and 40m (putting out 11 watts on 160, 8w on 80, 6w on 40m and about 3w on 20m).  How do I control output power and is there a way to jump to another band other than cranking the vfo?  Haven't wired up the mic yet.
<IMG_20180301_165829.jpg>
<IMG_20180301_165927.jpg>

Where to from here?

davidaker@...
 

This afternoon, I drilled out my enclosure (one of the mailboxes from Lowes) and wired it up and made a contact on 30m and 40m (putting out 11 watts on 160, 8w on 80, 6w on 40m and about 3w on 20m).  How do I control output power and is there a way to jump to another band other than cranking the vfo?  Haven't wired up the mic yet.

Re: Designing Maritime Radio #bitx40

qonita.salimah@...
 


Sorry this is the schematic picture

Re: Designing Maritime Radio #bitx40

qonita.salimah@...
 

Thank you for all of your reply

In this picture below, the Band Pass Filter is using a tunable inductor. But in the schematic files in hfsignals.com using a fixed inductor and capacitor.
 

Is there any advantage and disadvantage for these two types of passive components?

Thank you so much :)

Re: B40 LM386 and µB TDA2822 and that 470µF Cap

Jerry Gaffke
 

One observation that may or may not be relevant:
The datasheet from UTC spec's a supply voltage of 1.8 to 12v:  https://www.taydaelectronics.com/datasheets/A-1509.pdf
whereas the ST datasheet specs 1.8 to 15v:  https://www.taydaelectronics.com/datasheets/A-1003.pdf
Both spec an "Absolute Max" of 15v,
 


On Thu, Mar 1, 2018 at 03:39 pm, Jerry Gaffke wrote:
And that some clone TDA2822's may be weaker than mainline manufacturers.

Re: B40 LM386 and µB TDA2822 and that 470µF Cap

Jerry Gaffke
 

And subsequent replies have suggested this may not be sufficient.

Some seem to fry when plugging something into the headphone jack even if there is no short to ground involved.
Or when powering up the rig.
Our best guess now is that there are significant currents involved when that 470uF cap suddenly has to charge up to Vcc/2
And that some clone TDA2822's may be weaker than mainline manufacturers.


On Thu, Mar 1, 2018 at 03:31 pm, Christopher Miller wrote:
One of the first replies suggested not wiring the ring, and using a mono to stereo adapter cable if stereo headphones are required. 
 

Re: B40 LM386 and µB TDA2822 and that 470µF Cap

Christopher Miller
 

One of the first replies suggested not wiring the ring, and using a mono to stereo adapter cable if stereo headphones are required. 

Chris
KF4FTR

Re: B40 LM386 and µB TDA2822 and that 470µF Cap

Jerry Gaffke
 

It would be really really tough to fabricate a 100uF cap as part of a silicon wafer.
Datasheet specs the quiescent output voltage to be around half of the supply voltage,
right where you would expect it given the totem pole output driver.
As per post 43200.

And as alluded to in previous posts, the size of the cap is dictated by the impedance
of the load (typically 8 ohms) and the lowest frequencies you need to be hearing.

If you don't like the cap you can use the bridge topology in the datasheet,
using the two halves of the amp at 180 degrees out of phase.. 
But then neither side of your speaker is a ground potential. 
It's either that or a big cap, your choice. 


On Thu, Mar 1, 2018 at 02:56 pm, Arvo KD9HLC wrote:
Yes, but I'd think if someone was building an IC audio amp they'd go ahead and stick a cap inside it!

For Sale - Raduino (from uBITX kit)

n5ib_2
 

I have a never-used Raduino/NANO (optionally, with LCD display) for sale.
$25 postpaid to a USA address for just the Raduino/NANO, $30 postpaid USA for the Raduino/NANO and display.
Shippping to a DX address would be around US $15 and require a customs declaration.

These are the ones that came with my uBITX. I have replaced them with my "RadI2Cino" and a 4x20 display.
The Raduino board has the handwritten annotation "547/1" and "not programmed"

I'll ship it as is, or if the buyer sends me a ".zip" file with their choice of Arduino firmware, I will program the NANO.

Reply --OFF LIST PLEASE-- to n5ib (at) juno (dot) com if you're interested.

Jim, N5IB

Re: full rig power control unit

Glenn
 

There are some missing parts in the BOM also, C10 & C11. I assume 10nF (0.01uF)

glenn

Re: B40 LM386 and µB TDA2822 and that 470µF Cap

Arvo W0VRA
 

On Thu, Mar 1, 2018 at 02:38 pm, Gordon Gibby wrote:
The opamp output transistor circuit can only move between zero and a positive voltage.  
Yes, but I'd think if someone was building an IC audio amp they'd go ahead and stick a cap inside it!

I suppose different applications would have different optimum caps.

Re: full rig power control unit

Glenn
 

I'm thinking of doing a PCB for this but have a query about it's operation.

It seems to me that any detected fault turns on Q5, which in turn turns off Q1, which then has the effect of bringing up the 'Operate' LED D1 rather than the 'Fault' LED. ie they seem to be swapped over.

Has this Schematic actually been built and tested?

Glenn
vk3pe

Re: B40 LM386 and µB TDA2822 and that 470µF Cap

Gordon Gibby <ggibby@...>
 

The capacitor is there because this are you amplifier is designed to be operated with one supply voltage, +V, and ground.

The opamp output transistor circuit can only move between zero and a positive voltage.  

To avoid keeping a physical offset displacenent on the speaker cone, at the cost of significant current through its very low DC resistance! One adds a large capacitor in series to allow the speaker cone to rest at neutral position.

In the datasheet I looked at, they were using a 1000 µF capacitor.   That’s probably give you a better low frequency response, and basically the value isn’t that critical.



On Mar 1, 2018, at 17:20, Arvo KD9HLC via Groups.Io <arvopl@...> wrote:

Someone said if you find a fence ask why it's there before you tear it down.

On the B40 there is a 470µF cap on the output, between the LM386 output and the speaker.  On the LM386's TI datasheet Figure 10 there is a 250µF cap in that spot.  It's not an unreasonable leap to surmise that someone thought, "Hmmm, a 470 would probably work there and I've got a bunch of them."  I can't find anything in the datasheet explaining the need for the capacitor.  It may be that there is some DC offset in the output that needs to be removed.

On the µB there is also a 470µF cap between the output of the TDA2822 and the speaker.  On the TDA2822's STMicroelectronics datasheet application circuits there are examples with both 100µF and 470µF capacitors.  Again, I can't find why those caps are there.

The presence of these caps in the manufacturer's guidelines makes the "too much capacitor in the µB" hypothesis much less probable.  Maximum input voltage rating of 15V in the TDA2822 datasheet imply that 12-14V supplies should not be a problem, either.

A dead short on the output should not be a catastrophic problem for the amps because the caps are blocking DC current, so any power to be dissipated is associated with how loud you've got the volume knob cranked.  So if you turn it up and don't hear anything, turn it back down!

All bets are off if we have parts of unknown provenance, ie, counterfeits.  Does HF Signals have a process in place to assure the supply of components that conform to the expected specifications?  Bad batches of parts shouldn't happen from reputable suppliers.

All that said, there should probably be a pretty plain heads up somewhere in the tribal knowledge that if you wire up the µB speaker jack per the website and plug a TS (tip-sleeve) as opposed to a TRS (tip-ring-sleeve) male connector into it, you will have a dead short across the jack and it won't work properly.

One way to avoid that trouble is to simply wire the output of the amp to the tip connector of the jack and leave the ring connector of the jack floating (unconnected).  If you plug in a mono speaker, or an old fashioned earphone, it will work.  If you plug in stereo headphones you'll only hear audio from one earpiece.

I'm leaving mine wired for stereo.

Re: U1 fried

G1KQH
 

Recently I found some TDA2822's on ebay from China, I got the GQRP club to purchase a batch ( I bought 50 too ). Tony Fishpool (G4WIF) setup up a test and found although they worked well at low Volts they got hot over 7V!:


His findings are made public here on his website here: http://www.fishpool.org.uk/audioamp.htm


Food for thought!

73 Steve

GQRP 11049

http://g1kqh.blogspot.co.uk/