Date   
Re: BitX HW-16: full break-in high power ri

Jerry Gaffke
 

Ah, what the heck.
Topics are for veering off of.

No money back then, Heathkit was too expensive.
Was working with old TV parts and discarded WWII surplus (ARC-5's).
But I spent many hours digging through Heathkit catalogs.

These new kits are relatively expensive compared to stuff like the nanoVNA, but the website is persuasive.
I've got $100 bucks now.
And a thorough dislike for all the clocks I've bought in the last 20 years.

I hope they can get back into ham gear.

Jerry, KE7ER



On Sun, Sep 8, 2019 at 06:24 AM, Don--AE4DW wrote:
Trying not to veer too far off topic, but I remember seeing that resurected heathkit site several years ago, before they had any products to offer. It does look like they got it off the ground.

As another of those hams who started their operating experience with an HW-16 (circa 1976), and then upgraded to an HW-101, I still, to this day, appreciate what Heath stood for eons ago.

Re: BitX HW-16: full break-in high power ri

Jerry Gaffke
 

Yes, you could compromise receiver sensitivity without much downside if atmospheric noise still exceeds front end noise.
Though it is nice to be able to at least listen in when using a crummy antenna, such as a few feet of magnet wire
thrown across the floor.

In that 2018 paper on his website, W7ZOI simulates what a VNA would see using LTSpice.
When you build hardware, would be nice to verify the results using a cheap VNA such as
     https://www.alibaba.com/product-detail/Original-2-8-Touchscreen-50KHz-900MHz_62232701280.html
as discussed in     https://groups.io/g/nanovna-users

As mentioned previously in the forum, a VNA would not do the job of an Antuino
when sniffing out signals in a working radio.  The VNA can only see the results of a signal
that it injects into the circuit, at a frequency of its choosing.

Jerry, KE7ER


On Sat, Sep 7, 2019 at 11:44 PM, Tom, wb6b wrote:
On Sat, Sep 7, 2019 at 06:59 PM, Jerry Gaffke wrote:
Here's a 2018 treatment of T/R switches by W7ZOI, the Kang approach is figure 1:
    http://w7zoi.net/tr-qrp.pdf
A quick look at this article looks very good. I'm in the process of learning the Eagle Schematic capture and PCB design package. That package includes Ngspice. I can use the LTSpice schematic included in the article as a practice exercise for learning Eagle and Ngspice. As well as more about the operation of the T/R switch.

Just a thought though, if you were willing to comprise a little attenuation of the receive signal into the receive circuit and waste a little heat in a resistor while transmitting, maybe just using a resistor to limit the current flowing into the back to back diodes and a series resistor to the input of the receive circuit to keep the current there well below what would damage the receiver input, would work. That would work for a multi band transceiver. 

If you don't force the input of the receiver first stage to be 50 ohms and let it be significantly higher, the main resistor from the antenna connector to the back-to-back diodes could be a fairly high resistance. At HF the noise contributed by the receiver first stage is low compared to the main source of atmospheric noise, so a little signal loss wold not be a problem. (Of course, the answer to this is probably already covered in some part of these linked articles I have not read yet.)

I image there are receivers out there that don't bother to to supply 50 ohms, on receive, to the antenna terminal. I wonder how far you could deviate before the coax could create a 1/4 wave notch filter. I'm sure I'd end up cutting my coax just to the length so it would be a perfect 1/4 wave length at my favorite net's frequency.

Tom, wb6b

Re: BITX40

 

Roger,

Take the two antenna wires black and brown and twist them to minimize radiation and solder the black to the SO239 ground tab and
brown as you done. Keep those wires as short as possible.

Do the same for the Raduino RF out to the mother board.

All the long wires will add to the tuning click problem.

Raj


At 08-09-19, you wrote:

Thank you Vic.  The antenna is a 30’ vertical connected with RG213.  I have tried several aerials without hearing anything other than the clack clack of the tuning, whether the aerial is connected or not.  The display does indicate a frequency as you tune, although the range varies which you say is a design feature.

All the loose ends are taped as suggested in the online walk through.  I should have waited before buying the metal case which ended up costing more that the boards!  There are few connections necessary to get a signal that I’m thinking that the DDS board is faulty.

Picture of unit below.

Roger




On 8 Sep 2019, at 10:39 am, Vic WA4THR via Groups.Io < vhklein@...> wrote:

The frequency starting to step up or down at the ends of the tuning pot rotation is normal and part of the design to allow moving the tuning range. If you remember old SW receivers, it is kind of like the tuning is the bandspread control and at the ends you are adjusting the main tuning. Also, with no antenna connected the "clicks" when tuning are typical. If you upgrade to the Allard Munter sketch, those will be largely eliminated and you can further adjust the tuning range to your liking.

So, some more information is needed to understand the issue. What antenna do you have on the radio? Does the display indicate frequencies as you tune? Can you post a picture of the board and wiring?

=Vic=
[]  

Re: BitX HW-16: full break-in high power ri

Don--AE4DW
 

On Sat, Sep 7, 2019 at 12:42 AM, Tom, wb6b wrote:
On Fri, Sep 6, 2019 at 06:24 PM, Curt wrote:
my novice hw16 still lives
Interesting, I was looking around at sites that featured old Heathkit photos and product information. Found this link. Looks like someone is reviving Heathkit in Santa Cruz California. Maybe a nostalgic Dot Com millionaire? Much better than when Zenith was slapping the Heathkit name on cheap consumer products.

http://www.heathkit.com

Tom, wb6b
Trying not to veer too far off topic, but I remember seeing that resurected heathkit site several years ago, before they had any products to offer. It does look like they got it off the ground.

As another of those hams who started their operating experience with an HW-16 (circa 1976), and then upgraded to an HW-101, I still, to this day, appreciate what Heath stood for eons ago.

Re: T/R Relay sticking!

Evan Hand
 

The total for the board is less than 3 amps, and the PA is not switched.  There is not more than 500 ma being switched by the main T/R relay K1. K3 is handling the antenna switching between the PA and the receive front end.  That could have high RF induced currents that would be difficult to measure.  The other band switching relays are also handling the RF power.

With the above, we need to know which relay is sticking.

There is one other possibility, that is RF feedback into the rig causing the Nano to sense that a key is pressed. I had this issue with an off center fed dipole feeding back into the rig and causing it to lock up.  Have there been any changes to the shack right before the relay started sticking?  

Above are just some ideas.  Please take with a grain of salt and research before using.
73
Evan
AC9TU

Re: T/R Relay sticking!

 

Hi Chuck,

Has anyone measured the current that this relay is switching?  I wonder if it is exceeding the specification for these small relays which I think is normally 2A max.

In general though, I would expect a top brand relay would last longer.  Maybe you could try an Omron G5V-2 series relay. 

73,


Mark.

Re: BITX40

Roger Tuffin <roger.tuffin@...>
 


Thank you Vic.  The antenna is a 30’ vertical connected with RG213.  I have tried several aerials without hearing anything other than the clack clack of the tuning, whether the aerial is connected or not.  The display does indicate a frequency as you tune, although the range varies which you say is a design feature.

All the loose ends are taped as suggested in the online walk through.  I should have waited before buying the metal case which ended up costing more that the boards!  There are few connections necessary to get a signal that I’m thinking that the DDS board is faulty. 

Picture of unit below.

Roger




On 8 Sep 2019, at 10:39 am, Vic WA4THR via Groups.Io <vhklein@...> wrote:

The frequency starting to step up or down at the ends of the tuning pot rotation is normal and part of the design to allow moving the tuning range. If you remember old SW receivers, it is kind of like the tuning is the bandspread control and at the ends you are adjusting the main tuning. Also, with no antenna connected the "clicks" when tuning are typical. If you upgrade to the Allard Munter sketch, those will be largely eliminated and you can further adjust the tuning range to your liking.

So, some more information is needed to understand the issue. What antenna do you have on the radio? Does the display indicate frequencies as you tune? Can you post a picture of the board and wiring?

=Vic=

Re: BITX40

Vic WA4THR
 

The frequency starting to step up or down at the ends of the tuning pot rotation is normal and part of the design to allow moving the tuning range. If you remember old SW receivers, it is kind of like the tuning is the bandspread control and at the ends you are adjusting the main tuning. Also, with no antenna connected the "clicks" when tuning are typical. If you upgrade to the Allard Munter sketch, those will be largely eliminated and you can further adjust the tuning range to your liking.

So, some more information is needed to understand the issue. What antenna do you have on the radio? Does the display indicate frequencies as you tune? Can you post a picture of the board and wiring?

=Vic=

Re: BitX HW-16: full break-in high power ri

Tom, wb6b
 

On Sat, Sep 7, 2019 at 06:59 PM, Jerry Gaffke wrote:
Here's a 2018 treatment of T/R switches by W7ZOI, the Kang approach is figure 1:
    http://w7zoi.net/tr-qrp.pdf
A quick look at this article looks very good. I'm in the process of learning the Eagle Schematic capture and PCB design package. That package includes Ngspice. I can use the LTSpice schematic included in the article as a practice exercise for learning Eagle and Ngspice. As well as more about the operation of the T/R switch.

Just a thought though, if you were willing to comprise a little attenuation of the receive signal into the receive circuit and waste a little heat in a resistor while transmitting, maybe just using a resistor to limit the current flowing into the back to back diodes and a series resistor to the input of the receive circuit to keep the current there well below what would damage the receiver input, would work. That would work for a multi band transceiver. 

If you don't force the input of the receiver first stage to be 50 ohms and let it be significantly higher, the main resistor from the antenna connector to the back-to-back diodes could be a fairly high resistance. At HF the noise contributed by the receiver first stage is low compared to the main source of atmospheric noise, so a little signal loss wold not be a problem. (Of course, the answer to this is probably already covered in some part of these linked articles I have not read yet.)

I image there are receivers out there that don't bother to to supply 50 ohms, on receive, to the antenna terminal. I wonder how far you could deviate before the coax could create a 1/4 wave notch filter. I'm sure I'd end up cutting my coax just to the length so it would be a perfect 1/4 wave length at my favorite net's frequency.

Tom, wb6b

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

Jerry Gaffke
 

Reversing the power supply into the board can blow a bunch of stuff,
and thus be hard to fix.
But the fact that the Raduino works at all is a very good sign.

The Raduino is usually dead in the water after an event like this.
It is still possible that it is partially damaged (blown IO cells into the Nano?).
If a friend also has a uBitx, maybe try your Raduino in his uBitx to see if it works.
But it might have to be a very good friend.

If the encoder is wired up properly and the encoder did not come defective,
it should cause the frequency shown in the display to change.
If that does not work, check your wiring closely.
You can verify that the encoder is working properly with an ohmmeter,
disconnect it and measure the resistance from terminal A of the encoder 
(as shown in the wireup diagram) to terminal C.  It alternate between
open (thousands of ohms) and shorted (near zero ohms) as you rotate the knob.
Then do the same for between terminal B and terminal C.

If PA-PWR (the +12v into the IRF510 finals) got a reversed supply, then
look hard at L9 and the traces from it to the IRF510's and the PA-PWR connector.
Either L9 or the traces will fry, but probably not the IRF510's.
That could well be the source of your smoke.

With any luck at all, anything on the TX rail did not see -12v, only the RX rail saw -12v.
Most of the stuff that the RX rail goes to is pretty well protected by resistors, limiting current flow.
The LM386 at U1 and/or R71 could have blown, the 100 ohms at R71 would have limited currents
into U1 to 120ma absolute max but that's quite a lot.
I suspect most of the transistors would survive due to the nearby resistors, maybe all.

Once you prove out the Raduino somehow and have U1 working to where there's
a hiss in the headphones, you might try Farhan's procedure outlined here for the Bitx40:
    http://bitxhacks.blogspot.com/2016/12/troubleshooting-bitx40.html
Farhan is using a piece of wire maybe a meter long as an antenna to pick up
local QRM (digital clocks, microwaves, atmospheric noise)
and inject that noise into various parts of the receiver.

This could be very challenging to get working again.
Or you could be lucky.

Jerry, KE7ER


On Sat, Sep 7, 2019 at 08:09 PM, <gustav316@...> wrote:
Hi Jerry,
i am using the amateurradiokits.in enclosure, which comes with some extra items to wire up connections, one of which is a three pin connector for volume. What happened was that the red and black wires on the 12v power supply to the board were reversed, maybe 15 seconds of power supplied before I cut it.

i adjusted the contrast and the display is working and shows the frequency, although the encoder doesn’t seem to change the frequency. I am going to disassembly, check all of the solder joints and see if I can see any obvious visible damage to any components. Right now, I don’t see any, other than my on/off switch, which needs to be replaced since I need to hold it in to maintain the power on to the unit.

Re: BitX HW-16: full break-in high power ri

Tom, wb6b
 

On Sat, Sep 7, 2019 at 06:59 PM, Jerry Gaffke wrote:
Kang approach is in fig 2 of the W7ZOI article pointed to by post  https://groups.io/g/BITX20/message/70861
Hi,

That Wes Hayward article is pretty good. I'd recommend people read it, including myself.

I think at the time I found that article we were trying to figure out just how much like a PIN diode the 1N4007 rectifiers behaved. And if 1N4007 diodes from different manufactures might be different in regards to the "PINness" of their diodes. I skimmed right past the "Resonate T/R Switch" description. 

Tom, wb6b

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

Evan Hand
 

After I posted my replay, I read Jerry's recommendations.  I like the second receiver test for the BFO to verify that the Raduino RF section is working.  I will need to remember that for future references.  You can do that when powered by the USB connection as the Si5351a runs off of the 3.3v rail that comes from the Nano.

Another possibility for the source of the smell is it came from the volume control.  If you truly put 12v across it, and the wiper was close to one of the ends, you could have smoked it.  Since the resistor is behind a metal case, you may not see it without close inspection.  Run a resistance check on it as well.

73
Evan
AC9TU

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

gustav316@...
 

Hi Jerry,
i am using the amateurradiokits.in enclosure, which comes with some extra items to wire up connections, one of which is a three pin connector for volume. What happened was that the red and black wires on the 12v power supply to the board were reversed, maybe 15 seconds of power supplied before I cut it.

i adjusted the contrast and the display is working and shows the frequency, although the encoder doesn’t seem to change the frequency. I am going to disassembly, check all of the solder joints and see if I can see any obvious visible damage to any components. Right now, I don’t see any, other than my on/off switch, which needs to be replaced since I need to hold it in to maintain the power on to the unit.

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

Evan Hand
 

Gus,

As a potential way of isolating the fault, you can unplug the Raduino from the main board and run the Raduino from a USB port on your computer, or other 5 volt supply.  That would let you know if the display and Nano are OK.  If you do this, you do not need the controls connected to the 8 pin connector on the Raduino.  plug a microUSB cable into the Nano on the RAduino and into a PC or other USB 5 volt source.  The display should light up, and you should see the normal startup screen.  If I interpreted your description, you put the 12 v power to the volume control connections on the uBITX board.  That could have taken out the Nano on the Raduino, as there is a connection to the Nano for CW side tone.  The Nano does not like anything over 5v or under 0v relative to the common on the Nano.  Nano's are cheap, so no big deal if you need to replace it.  Just make sure that you get one WITHOUT the headers already soldered, as they need to go on the other side of the board to work in the uBITX.

If that does work, then the Raduino is Probably OK.

Going beyond that will depend on the test equipment that you have.

By the way, did you do the test in step two of the wire up instructions from HF Signals?
http://www.hfsignals.com/index.php/ubitx-wire-up/

I would do that test to verify that the board is still operational.  Note that the Raduino is NOT installed when measuring the current.

73
Evan
AC9TU

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

Jerry Gaffke
 

Gus,

This is not very clear to me:

>  However, I mistakenly switched two of the three wire cables.
>  The one that I used for the power was supposed to be for the volume control.
>  Normally there would not likely be an issue but for the fact that the way
>  the connector attached to the board, the polarity was actually reversed 

The volume control on the uBitx is wired up to an 8 pin connector,
the power supply goes into a 3 pin connector.  Would be hard to swap them.
Exactly what pin did you connect the +12v wire from your power supply into?
Exactly what pin did you connect the ground wire from your power supply into?

It is possible for those caps to be damaged by reverse polarity.
But if you see no apparent damage, they are probably in good enough shape.

Reverse polarity on the main +12v rail will pretty much destroy the Raduino 
and also blow a bunch of parts on the main board.  That would be difficult to repair.

I think I would first try to get that Raduino working.
You can unplug it from the radio, feed it between 8 and 12 volts, and see if you can 
get the display to work.  If the display works, see if you can hear the BFO by tuning in
a nearby shortwave receiver to 11.059mhz, listen for a clear CW tone with a piece of
wire for an antenna from the receiver coming within a couple inches of the Raduino.
If the display works and you can hear that tone, the Raduino is fine.

If what you did was wire your power supply into VOL-M and/or VOL-H and/or Ground
(the three volume control wires), I'd think the damage would be limited to the LM386 at U1.
Do you see obvious cracks or craters in the case of U1?
Q74 might have been hurt, but I doubt it.  There is a possibility that a negative supply on VOL-M
could have gotten through the LM386 into the +12v rail, but the 100 ohms at R74 would
somewhat limit the current available for wrecking havoc.
 
Jerry, KE7ER


On Sat, Sep 7, 2019 at 06:41 PM, <gustav316@...> wrote:
Thank you, Mark. I do have the 4.7k ohm resistor installed and I will try to adjust the contrast as well. Perhaps that will fix the issue, save for my switch, which is not functioning and needs to be replaced. If not, I will try to swap out the caps, but hopefully the very short application of reverse polarity didn’t totally damage them. I appreciate your response.

-Gus
W9SSN

Re: BitX HW-16: full break-in high power ri

Jerry Gaffke
 

Tom,

The Kang approach is in fig 2 of the W7ZOI article pointed to by post  https://groups.io/g/BITX20/message/70861
That article mentions Roy Lewellen, W7EL, and his "Optimized Transceiver" in the Aug 1980 QST
as a possible source for what W7ZOI considers this "standard" T/R switch.
Here's a 2018 treatment of T/R switches by W7ZOI, the Kang approach is figure 1:
    http://w7zoi.net/tr-qrp.pdf

Oh, and post 70861 was from Tom, WB6B.
I've probably seen the circuit over the years as well, 
never quite realizing how it worked.

Jerry, KE7ER

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

gustav316@...
 

Thank you, Mark. I do have the 4.7k ohm resistor installed and I will try to adjust the contrast as well. Perhaps that will fix the issue, save for my switch, which is not functioning and needs to be replaced. If not, I will try to swap out the caps, but hopefully the very short application of reverse polarity didn’t totally damage them. I appreciate your response.

-Gus
W9SSN

Re: BitX HW-16: full break-in high power ri

Tom, wb6b
 

On Sat, Sep 7, 2019 at 06:34 AM, Jim Willis wrote:
IBM Huntsville, they showed me their navigation system comprising three microprocessors “voters” and an analog “patch panel” navigation computer.  I was hooked!
I can imagine what that was like. I did not work in the space race, but, as a kid, a friends father worked for Autonetics and he would bring us to their employee open house events and we would get to see all this amazing technology set up on display in various labs. For a kid it was mind boggling to see this stuff and in many lucky instances, someone was there to try to explain it to a kid. 

I just looked at this video where a new tech person gets to talk with an IBM Huntsville engineer from the day. He really seems to get a feeling for the technology of the day and the amazing things accomplished at that state of the art.

https://www.youtube.com/watch?v=6mMK6iSZsAs

What it must have been like to thrust a monstrous machine off the earth with a huge controlled explosion, with a control technology that had a main program loop cycle time of two seconds, to actually keep this monster on track.

Tom, wb6b

Re: I am an idiot. Did I fry my v. 5 board? #ubitx-help #ubitx40help

 

Hi Gus,

Well, if you smelled something then likely something got a bit too hot!

A couple notes:

The black squares on the display is normal if you haven't adjusted the contrast for the diplay yet (small smt pot on the board).

Looking at the schematic I notice two places where reversed power will end up with a circuit with electrolytic capacitors hooked up backwards.  Check the schematic for these (one is the power line to the lm386 audio chip -- the other is nearby).  Electrolytic capacitors don't like being hooked up backwards and are likely permanently damaged.  I would replace them with similar value parts.

You should get a good magnifier out and a strong light and examine both boards well for burnt traces.   If you find any, note any parts connected to the traces as they may need to be investigated for damage.

Make sure you have the CW key resistor in place -- the board will stay in transmit and never go to receiver unless this is installed.

Finally, see recent posts about reverse polarity protection :-0

73,


Mark.

Re: Graphics files for Nextion LCD displays.

John Scherer
 

Thanks much Mark..
--
John - N0CTL - Fulltime RV in a 40' motorhome