Date   
Re: no audio

Sam Tedesco
 

Got it. Thanks for all the suggestions

Re: V5 audio Help !

Arv Evans
 

Chuck

The VOL-High side of the volume control is probably not the culprit unless the volume
potentiometer hot side has become shorted to ground.  Temporarily shorting this to ground
would probably not damage anything. 

If you look at the circuit as a set of function blocks it should be possible to trace the problem
to its cause.  Try to avoid shotgun approaches where you jump around without a logical
approach.  If my memory is correct I think you are working on a uBITX, Version-5...?
The information on this is located at this URL:


The receive and transmit and audio mute circuit sections are described in that web page.
In this part of the circuit, The LM386 section is relatively easy to comprehend but the rest
of the circuit segment does seem to be a bit difficult to understand.  So lets take a look at
what parts perform which function.
 
ubitx_v5_audio-768x231.png

Q8 on the right is the transmit audio from microphone to BFO mixer.  This is probably not
involved in your receive audio problem.

Receive audio comes in on the right, from the BFO mixer at the common point of C63 and C50. 
It passes through C50 to the base of Q70.  Q70 amplifies this receive audio with output on the
collector and through C51.  Voltage for Q70 is provided in receive mode only via R51 and R51. 
C52 is a filtering capacitor to help isolate Q70 from extraneous signals that might be riding on
the DC power lead.

The left end of C51 is shown connected to connector pin M1.  On the main schematic points M1,
M2, M3, and M4 are shown as connected permanently to ground.  This is apparently an error in
the main diagram. 

Wiring for the volume control potentiometer is shown in URL:

ubitx_wiring.svg_-1.png

Audio output from Q70 collector goes through C51 to the HIGH side of the volume control
(VOL-H on the diagram).  This is a yellow wire from the plug on the main board.  Ground
for the volume control is on the Green wire from the plug on the main board.  Audio out
from the volume control is on the Orange wire labeled VOL-M on the drawing.

NOTE:  Q74 appears in the receive audio path but is used as an ON-OFF switch to
shunt receive audio to ground during transmit modes.  It is ON when transmitting and
an open circuit when receiving.  It is driven by T/R voltage (high in transmit mode and
ground in receive mode). 

Audio from the wiper of the volume control (VOL-M Orange wire) enters the LM386 on
input pin-3 and goes to the speaker/headphone jack from pin-5. 

Okay...you now have some detail on the receive audio path in your uBITX transceiver.
Depending on level of experience you may be able to troubleshoot the problem.  If not
please let us know and we can take the signal tracing and detection on a step-by-step
basis. 

Arv  K7HKL
_._






On Fri, Jun 7, 2019 at 11:14 PM chuckr@... <chuckr@...> wrote:
Hi, as mentioned first symptoms was the sudden drop in audio to near nothing after an attempt to wire audio to the mike plug ( second round four pin connector) for digital use. All was working fine until this point , I think i may have caused the Vol-H to get grounded. I have reversed all that I was doing and all wiring etc. to where it was last working at which time the audio would adjust so loud that one would have to cover their ears. For a day or so the audio was  still barely there and you could still tune around . as time went and I tried two lm386 and now the audio is completely gone except for the low clicking of the encoder as it turns.
All i have for testing is a multi-meter. I have checked all wiring for continuity. The radio still tunes and transmits as when it was new a couple weeks ago. I know this info is lacking and not really very tech but I will try to answer / our questions etc.
Thanks much
chuck

Re: Nextion display cutout and mounting. #ubitx #ubitx-help

Eric Carter
 

Hi Ian,

Plugging the two line display in was the first thing I did for troubleshooting. The display responded to all commanded inputs.It  came from my troubleshooting aircraft electronics for 
Years. 

Regards,

Eric

On Sat, Jun 8, 2019, 17:53 Ian Reeve <ian.radioworkshop@...> wrote:

Hi Eric,

 

Do you still have the original 2 line display?  If so carefully plug that in to the header pins to see if that responds to the rig controls.

 

Are you using KD8CEC software on the Arduino or is it still the original ubitx?

 

If the 2 line display responds to the rig commands, the Arduino must be working properly and as long as the connections are correct to the Nextion and you are using KD8CEC software on the Arduino I can only suggest the display is faulty.

 

Seems strange though that you successfully loaded the image onto the Nextion, I would have thought a faulty screen would have not loaded the image

 

Regards

 

Ian

 

Sent from Mail for Windows 10

 


From: BITX20@groups.io <BITX20@groups.io> on behalf of Eric Carter <e.o.carter1@...>
Sent: Saturday, June 8, 2019 3:16:54 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Nextion display cutout and mounting. #ubitx #ubitx-help
 
Hi Ian,

I checked the resistance and continuity of the connections with a multimeter and found no issue. Bummer. I wish it could have been that simple. I am beginning to wonder if there is a problem with the Nextion display itself.

Regards,

Eric

Re: Simple construction idea

Ashhar Farhan
 

brilliant


On Sat, Jun 8, 2019 at 7:14 PM Jack Purdum via Groups.Io <jjpurdum=yahoo.com@groups.io> wrote:
All:

I've been working with a small (2.4") TFT touch screen display for a CW messaging system. The display has 14 pins on the right edge of the display, with their ID's silk screened on the back side of the display. During the course of building the circuit, I probably flipped the display front-to-back...oh, I don't know...about a bazillion times. Al (AC8GY) had a great , but simple, time-saving idea, as shown here:

Inline image

He cut some scrap from an Avery label sheet and just stuck it on the display. Well worth the effort for almost any device that has silk screening on the back but you need to work with it from the front. If need be, it's easy to peel the label off when you're done.

Jack, W8TEE

Re: Nextion display cutout and mounting. #ubitx #ubitx-help

Eric Carter
 


Hey Ian,


I am still running the  CEC firmware.

Eric

On Sat, Jun 8, 2019, 20:31 Eric Carter via Groups.Io <e.o.carter1=gmail.com@groups.io> wrote:
Hi Ian,

Plugging the two line display in was the first thing I did for troubleshooting. The display responded to all commanded inputs.It  came from my troubleshooting aircraft electronics for 
Years. 

Regards,

Eric

On Sat, Jun 8, 2019, 17:53 Ian Reeve <ian.radioworkshop@...> wrote:

Hi Eric,

 

Do you still have the original 2 line display?  If so carefully plug that in to the header pins to see if that responds to the rig controls.

 

Are you using KD8CEC software on the Arduino or is it still the original ubitx?

 

If the 2 line display responds to the rig commands, the Arduino must be working properly and as long as the connections are correct to the Nextion and you are using KD8CEC software on the Arduino I can only suggest the display is faulty.

 

Seems strange though that you successfully loaded the image onto the Nextion, I would have thought a faulty screen would have not loaded the image

 

Regards

 

Ian

 

Sent from Mail for Windows 10

 


From: BITX20@groups.io <BITX20@groups.io> on behalf of Eric Carter <e.o.carter1@...>
Sent: Saturday, June 8, 2019 3:16:54 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Nextion display cutout and mounting. #ubitx #ubitx-help
 
Hi Ian,

I checked the resistance and continuity of the connections with a multimeter and found no issue. Bummer. I wish it could have been that simple. I am beginning to wonder if there is a problem with the Nextion display itself.

Regards,

Eric

Re: Nextion display cutout and mounting. #ubitx #ubitx-help

Ian Reeve
 

Hi Eric, You have covered all areas I can think of so that only leaves the screen and perhaps the two.wires blue and yellow to nextion.won't harm anything so perhaps stop around the blue and yellow wires at the session end. Good luck


From: BITX20@groups.io <BITX20@groups.io> on behalf of Eric Carter <e.o.carter1@...>
Sent: Saturday, June 8, 2019 7:52:37 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Nextion display cutout and mounting. #ubitx #ubitx-help
 

Hey Ian,


I am still running the  CEC firmware.

Eric

On Sat, Jun 8, 2019, 20:31 Eric Carter via Groups.Io <e.o.carter1=gmail.com@groups.io> wrote:
Hi Ian,

Plugging the two line display in was the first thing I did for troubleshooting. The display responded to all commanded inputs.It  came from my troubleshooting aircraft electronics for 
Years. 

Regards,

Eric

On Sat, Jun 8, 2019, 17:53 Ian Reeve <ian.radioworkshop@...> wrote:

Hi Eric,

 

Do you still have the original 2 line display?  If so carefully plug that in to the header pins to see if that responds to the rig controls.

 

Are you using KD8CEC software on the Arduino or is it still the original ubitx?

 

If the 2 line display responds to the rig commands, the Arduino must be working properly and as long as the connections are correct to the Nextion and you are using KD8CEC software on the Arduino I can only suggest the display is faulty.

 

Seems strange though that you successfully loaded the image onto the Nextion, I would have thought a faulty screen would have not loaded the image

 

Regards

 

Ian

 

Sent from Mail for Windows 10

 


From: BITX20@groups.io <BITX20@groups.io> on behalf of Eric Carter <e.o.carter1@...>
Sent: Saturday, June 8, 2019 3:16:54 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Nextion display cutout and mounting. #ubitx #ubitx-help
 
Hi Ian,

I checked the resistance and continuity of the connections with a multimeter and found no issue. Bummer. I wish it could have been that simple. I am beginning to wonder if there is a problem with the Nextion display itself.

Regards,

Eric

uBITX all bander new wire-up. LCD flashes on-off repeatedly

Neil Tolman
 

uBITX all bander new wire-up. LCD flashes on-off repeatedly.  Anyone else had this problem?
Thank you
73
Neil

Re: uBITX all bander new wire-up. LCD flashes on-off repeatedly

Mark Hatch
 

If you were using a Nextion display, I have seen this  when only powering via USB.

73
Mark

Re: Simple construction idea

Doug W
 

I wonder how long it is going to take for this palm print to fade from my forehead?  
--
www.bitxmap.com

Re: uBITX all bander new wire-up. LCD flashes on-off repeatedly

Neil Tolman
 

Hi Mark,
Thank you for your answer.
It's fully powered by a fused cord off a a bank of 12 volt batteries. The voltage at the time was 12.7 volts.
Neil

On Saturday, June 8, 2019, 5:13:27 PM EDT, Mark Hatch <mark2382@...> wrote:


If you were using a Nextion display, I have seen this  when only powering via USB.

73
Mark

Re: Nextion display cutout and mounting. #ubitx #ubitx-help

john terry
 

Hi eric

I don’t have an answer, but admit I have had two Nextion displays that would not update. One 2.8 read card as incompatable, the second 3.2 just did nothing. I suspect incompatable Knock offs. These were marked Nextion, but not Itead.
Model numbers were correct. 

John N0jt 

On Sat, Jun 8, 2019 at 3:49 AM Eric Carter <e.o.carter1@...> wrote:
Hi Derek,

I have the Nextion 3.2" model NX4024K032_011R. I have not had any success updating the firmware to my display. I tried the TFT and HMI files. Do you have any suggestions as to what to try to resolve this?

Eric Carter 

Re: V5 audio Help !

chuckr@hostu.org
 

Hi to all that have responded, I'am pretty sure I have found the problem, and will share the embarrassing  and simple fix if indeed this is the whole of my problem. It is late and just returned home from my grandson's wedding and tomorrow is Sunday and Church, so will be Monday before completion of my repair. Stay tuned for the tell of a funny, almost if not dumb rookie type mistake.
chuck
73 all

uBitx V3 transmit probles.

Dennis Yancey
 

I have a V3 that just quit transmitting. It appeared the finals just went out. I replaced the finals (used sockets per advice from another user) and still no output. It is a good thing that I put them in sockets as now one of the new finals is bad. I decided to leave the finals out and test all the Transmit test points per the Diagnostic guide. When I test all the test  points, the values are good both in transmit and receive mode, the transmitter section seems to be working as it should. 

I hooked up my straight key and tested it in cw mode. The transmit section again looked good as far as the voltages go. Remember there are no finals and on pin 2 of the IRF510 I am getting a voltage reading when transmitting and a constant voltage of 12 volts on pin 2 all the time. Nothing of course on pin 3 as there is no 510 in place. 

When I put an IRF510 in each socket, the one in Q94 looks normal but immediately the one in Q95 goes to 10 volts on pin 1. Where is this coming from and why? I have gone through 3 IRF510s in that location now, testing each one on my tester before installation. 

Any ideas? Kind of at my wits end (actually that happened when I turned 13, but that's another story)..... 

Thanks in advance for the always helpful and illuminating ideas. 

God bless
Dennis, KD4EPG
--
72 and God bless
KD4EPG

Re: uBITx v5 - with mods

MVS Sarma
 

Ravi jee, 
Just use kd8cec , select the lcd type in ubitx.h, select ver5 on main file, just compile. 

Later pwer on Nd while calibrating  change bfo to 1105550 and click ptt and save. Also power cycle.
Later select wwv and complete calibration.if needed few steps of bfo.

You should succeed. Atb
Sarma vu3 zmv



On Sat, 8 Jun 2019, 8:14 pm Ravi Miranda <ravimiranda@... wrote:
Hi All,

Apologies for the long post.

Background
I built a V5 using the circuit here:
http://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

I have also included the mods (BFR106) and changed the resistors as
specified. Only the RX stage has been enabled.
For the stages I used :
http://w7zoi.net/bidirectional_matched_amplifier.pdf keeping the
original values intact

The ladder crystal filter has been built with 11.0592 Mhz Crystals.

The voltages for the RX side (only) transistors are as follows:
Q10 [C] (9.33)     [B] (2.02)      [E] (1.31)
Q11 [C] (11.69)    [B] (9.33)     [E] (8.62)
Q12 [C] (11.69)    [B] (8.62)     [E] (7.89)


Q30 [C] (9.12)     [B] (2.06)      [E] (1.38)
Q31 [C] (11.69)    [B] (9.12)     [E] (8.45)
Q32 [C] (11.69)    [B] (8.45)     [E] (7.75)

I have not used the AGC circuit as given in the original V5 but opted
for the LM324 version. However, this is not  enabled.

I have taken the Panadapter out from just before the ladder filter
(post the stage 2 TIA). This is connected to SDRSharp to check signals

For the software, I used the V1.2  with frequencies calculated based on KD8CEC:
http://www.hamskey.com/2019/02/whats-new-with-ubitx-v5-1-changed-if.html

I  used the following values:
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)

#define INIT_USB_FREQ (11059250l)

According to the notes in KD8CEC's blog the firstIF has been set to
45005000L due to L7 and L5 pulling the crystal filter by 5KHz

Using the PanAdapter tap point that has been provided for I can see
that the signal passes through at just about 45.000.000 MHz, but at
times (start up) the signal can be heard on SDR# on 44.993.400.


Going backwards, I have used a signal injector from the input of the
audio amp to the output of the crystal stage and have a good noise
injection level at the speaker. If I use the signal injector at the
input side of crystal filter there is no sound.

I am using a local MW station on 1458KHz as this is the only station
that I can hear via SDR# (AM). The beat seems correct.

I can hear this station on the uBITx speaker very faintly (if I put my
ear next to it).

I am unable to copy any Ham stations or WWV or any other HF broadcast stations.

On start up I can hear a slight crackling noise through the speaker,
but have no clue where this is being generated.

To ensure that the SI5351 was calibrated correctly I used :
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch

and saved the value in the program

I have a RF milivoltmeter (homebrew) using a AD8307 and LM358
(uncalibrated), this is showing signal levels at testpoints. I haven't
done a thorough test at all points yet.

I have injected a 20mV(approx) using a AD9851 into the antenna input I
can hear the zero beat (14.150). With a stronger signal injection the
speaker jumps around quite a bit :-)

I have the following few questions ( few)
1. How do I know that the uBITx is tuned correctly
2. The volume level through the speaker is very poor.
3. Are the voltage levels on the transistors correct?
4. Shouldn't the Pandadapter (RTL dongle + SDR#) show the spectrum of
a larger bandwidth rather than just the tuned frequency at 45MHz?
5. Are the stages amplifying correctly?
6. How do I locate the source of the crackling? This dies down in a few mins.

I have access to a DSO, what checks can I do to verify the working and
improve the sound level?

Thoughts suggestions and comments welcome.

Sorry once again for the long post and thanks for reading. Have a great weekend.

Best 73,

Ravi/M0RVI










--
I'm here to add more value to the world than I'm using up.



Re: uBitx V3 transmit probles.

 

If the blue bias pot is slightly skewed then one lead could be cut. Replace.

Remove Q95 and check gate voltage as you vary the associated preset RV2. It should go from
0-5V. If not replace and set the bias again.

Raj

At 09-06-19, you wrote:
I have a V3 that just quit transmitting. It appeared the finals just went out. I replaced the finals (used sockets per advice from another user) and still no output. It is a good thing that I put them in sockets as now one of the new finals is bad. I decided to leave the finals out and test all the Transmit test points per the Diagnostic guide. When I test all the test points, the values are good both in transmit and receive mode, the transmitter section seems to be working as it should.

I hooked up my straight key and tested it in cw mode. The transmit section again looked good as far as the voltages go. Remember there are no finals and on pin 2 of the IRF510 I am getting a voltage reading when transmitting and a constant voltage of 12 volts on pin 2 all the time. Nothing of course on pin 3 as there is no 510 in place.

When I put an IRF510 in each socket, the one in Q94 looks normal but immediately the one in Q95 goes to 10 volts on pin 1. Where is this coming from and why? I have gone through 3 IRF510s in that location now, testing each one on my tester before installation.

Any ideas? Kind of at my wits end (actually that happened when I turned 13, but that's another story).....

Thanks in advance for the always helpful and illuminating ideas.

God bless
Dennis, KD4EPG

Re: uBITx v5 - with mods

Ashhar Farhan
 

ravi,
which firmware version are you using? it might help to trace a signal. inject a 100mv signal and trace it with a scope on the rx path..
- f

On Sun, Jun 9, 2019 at 11:35 AM MVS Sarma <mvssarma@...> wrote:
Ravi jee, 
Just use kd8cec , select the lcd type in ubitx.h, select ver5 on main file, just compile. 

Later pwer on Nd while calibrating  change bfo to 1105550 and click ptt and save. Also power cycle.
Later select wwv and complete calibration.if needed few steps of bfo.

You should succeed. Atb
Sarma vu3 zmv



On Sat, 8 Jun 2019, 8:14 pm Ravi Miranda <ravimiranda@... wrote:
Hi All,

Apologies for the long post.

Background
I built a V5 using the circuit here:
http://www.hfsignals.com/wp-content/uploads/2019/02/ubitx_v5.pdf

I have also included the mods (BFR106) and changed the resistors as
specified. Only the RX stage has been enabled.
For the stages I used :
http://w7zoi.net/bidirectional_matched_amplifier.pdf keeping the
original values intact

The ladder crystal filter has been built with 11.0592 Mhz Crystals.

The voltages for the RX side (only) transistors are as follows:
Q10 [C] (9.33)     [B] (2.02)      [E] (1.31)
Q11 [C] (11.69)    [B] (9.33)     [E] (8.62)
Q12 [C] (11.69)    [B] (8.62)     [E] (7.89)


Q30 [C] (9.12)     [B] (2.06)      [E] (1.38)
Q31 [C] (11.69)    [B] (9.12)     [E] (8.45)
Q32 [C] (11.69)    [B] (8.45)     [E] (7.75)

I have not used the AGC circuit as given in the original V5 but opted
for the LM324 version. However, this is not  enabled.

I have taken the Panadapter out from just before the ladder filter
(post the stage 2 TIA). This is connected to SDRSharp to check signals

For the software, I used the V1.2  with frequencies calculated based on KD8CEC:
http://www.hamskey.com/2019/02/whats-new-with-ubitx-v5-1-changed-if.html

I  used the following values:
#define SECOND_OSC_USB (56054200l)
#define SECOND_OSC_LSB (33940800l)

#define INIT_USB_FREQ (11059250l)

According to the notes in KD8CEC's blog the firstIF has been set to
45005000L due to L7 and L5 pulling the crystal filter by 5KHz

Using the PanAdapter tap point that has been provided for I can see
that the signal passes through at just about 45.000.000 MHz, but at
times (start up) the signal can be heard on SDR# on 44.993.400.


Going backwards, I have used a signal injector from the input of the
audio amp to the output of the crystal stage and have a good noise
injection level at the speaker. If I use the signal injector at the
input side of crystal filter there is no sound.

I am using a local MW station on 1458KHz as this is the only station
that I can hear via SDR# (AM). The beat seems correct.

I can hear this station on the uBITx speaker very faintly (if I put my
ear next to it).

I am unable to copy any Ham stations or WWV or any other HF broadcast stations.

On start up I can hear a slight crackling noise through the speaker,
but have no clue where this is being generated.

To ensure that the SI5351 was calibrated correctly I used :
https://groups.io/g/BITX20/wiki/Si5351-Calibration-Sketch

and saved the value in the program

I have a RF milivoltmeter (homebrew) using a AD8307 and LM358
(uncalibrated), this is showing signal levels at testpoints. I haven't
done a thorough test at all points yet.

I have injected a 20mV(approx) using a AD9851 into the antenna input I
can hear the zero beat (14.150). With a stronger signal injection the
speaker jumps around quite a bit :-)

I have the following few questions ( few)
1. How do I know that the uBITx is tuned correctly
2. The volume level through the speaker is very poor.
3. Are the voltage levels on the transistors correct?
4. Shouldn't the Pandadapter (RTL dongle + SDR#) show the spectrum of
a larger bandwidth rather than just the tuned frequency at 45MHz?
5. Are the stages amplifying correctly?
6. How do I locate the source of the crackling? This dies down in a few mins.

I have access to a DSO, what checks can I do to verify the working and
improve the sound level?

Thoughts suggestions and comments welcome.

Sorry once again for the long post and thanks for reading. Have a great weekend.

Best 73,

Ravi/M0RVI










--
I'm here to add more value to the world than I'm using up.



Re: Preliminary results -- W8TEE/AC8GY Mag Loop Testing

EI4GNB
 

I knocked up a 3-turn loop, with an old soviet era vac-cap, total length was 10m of copper tube, and it covered 160m thru' 30m and did work very well, although the bandwidth was so skinny on topband, it did not allow for use of the internal tuner in my rig, tuning slightly off the SSB frequency as auto-tuners do when using a carrier. It just weighed so much that it was impractical. Did manage trans-atlantic on FT8 on Topband using it, so not all bad.

Next i tried using LM400 coax instead of the copper in a single loop, with 2 favourite lengths in the kit and a much smaller Vac-Cap, and i can work 40m thru' 6m by swapping out the coax (basically a long patch lead) and doing a slight tweak to the vari cap. I housed everything in an ABS box with SO239 for the coax loop connected to the cap, and i mount it on a small fibreglass pole, strapping it to whatever is available with luggage/shipping straps when out & about. Sure beats end-feds or tryign to support a vertical or inverted V etc.

I feed all my loops with a ferrite ring BTW, just dangling on the coax loop opposite the cap which is in the ABS box the loop hangs from.

Sure, this ain't no 'Cloudburn 5000 XL-DX Superblast multi-element face-melter' of an antenna, but it punches WAY above it's weight, and if You get lucky, You may even catch something to eat with it.

Re: Preliminary results -- W8TEE/AC8GY Mag Loop Testing

Robert D. Bowers
 

A friend of mine reported very good results with one of the loop antennas sold by MFJ (40-6 coverage as I remember).  He liked it because of the noise problem - here it can be a huge issue (not unusual to have S9 noise at least a couple hours out of the day, and some days 20-40db over the whole day).  He got out fine - but the big difference is that he could hear others.  (I've been thinking about building a loop - because of the noise, but even more so because they're small and work without being high up - and this area IS bad for lightning (a couple of direct hits on the tower over the years and many strikes within a couple of hundred feet at most, only a few repairs needed in the shack due to very good grounding, a disconnect 'patch board', and careful layout).

This thread reminds me of what I was told about a person wanting to run 40m (I think it was for a contest, but for something 'special').  He made up a quicky dipole and just threw it across the tops of some bushes, a few feet off the ground.  He said it worked GREAT, so much so that a couple of other hams were going to try it.  You wouldn't think it would work so good, but he said he did really well with it.

Another story - there was a huge sinkhole that suddenly formed here in Florida.  A ham lived just outside of the danger zone, and reported differences in how his antennas operated as the water level (immediate water table) rose in the sinkhole.  (I don't remember if his setup worked better or worse - just that it changed.)

The thing is, every ham lives in a different situation... different factors that will strongly affect the performance of their antennas.  Good ground and conductive soil (moisture) vs dry desert and poor ground, you name it.  If one has an idea for an antenna, try it.  It might be just what is needed in that person's situation - and it's great fun trying.  That's part of learning the electronics/radio portion of Amateur Radio... so you can have ideas of how to work around issues you may encounter (like poor grounding).  That's just part of being a good op.

Bob

N4FBZ

On 6/9/19 10:14 AM, EI4GNB wrote:
I knocked up a 3-turn loop, with an old soviet era vac-cap, total length was 10m of copper tube, and it covered 160m thru' 30m and did work very well, although the bandwidth was so skinny on topband, it did not allow for use of the internal tuner in my rig, tuning slightly off the SSB frequency as auto-tuners do when using a carrier. It just weighed so much that it was impractical. Did manage trans-atlantic on FT8 on Topband using it, so not all bad.

Next i tried using LM400 coax instead of the copper in a single loop, with 2 favourite lengths in the kit and a much smaller Vac-Cap, and i can work 40m thru' 6m by swapping out the coax (basically a long patch lead) and doing a slight tweak to the vari cap. I housed everything in an ABS box with SO239 for the coax loop connected to the cap, and i mount it on a small fibreglass pole, strapping it to whatever is available with luggage/shipping straps when out & about. Sure beats end-feds or tryign to support a vertical or inverted V etc.

I feed all my loops with a ferrite ring BTW, just dangling on the coax loop opposite the cap which is in the ABS box the loop hangs from.

Sure, this ain't no 'Cloudburn 5000 XL-DX Superblast multi-element face-melter' of an antenna, but it punches WAY above it's weight, and if You get lucky, You may even catch something to eat with it.

Re: Preliminary results -- W8TEE/AC8GY Mag Loop Testing

ajparent1/KB1GMX <kb1gmx@...>
 

Alan de G1FXB

Jun 1
   

I recall you done antenna R&D.

Yes, I did for a commercial firm that was biased toward research and specialized designs.

EH antennas, based on work and research are a great way to make the coax radiate.
The antenna is often near the lower limits and radiates poorly but the coax shield is often long
enough to be effective on 160.

Do they work, for some measure of "works" yes sorta.  Hint do not choke the shield.
A better statement is that better antennas are likely possible in the same volume.

Every time I see that I go back to first principles and examine the system.

Allison

Re: Preliminary results -- W8TEE/AC8GY Mag Loop Testing

ajparent1/KB1GMX <kb1gmx@...>
 

Where I stand on loops:

Based on design work and in use.  Loop antennas are useful either in the
wide band receiving only type or tuned transmitting type.  They are not
close to full size dipoles in performance never minding beams.  However
they are self contained, compact, have a pair of very deep directional nulls.
Those features often offset the low gain and touchy tuning and on the
low bands like 80 and 160 they can be very useful even RX only for beating
local noise issues.  Often that is more important then how big your signal is.

As such Loops along with dipoles and other well understood antennas be part
of the hams box of tricks to enable communications.  

Bob/N4FBZ nails it:

"The thing is, every ham lives in a different situation... different factors that will strongly affect the performance of their antennas. 
Good ground and conductive soil (moisture) vs dry desert and poor ground, you name it.  If one has an idea for an antenna, try
it.  It might be just what is needed in that person's situation - and it's great fun trying.  That's part of learning the electronics/radio
portion of Amateur Radio... so you can have ideas of how to work around issues you may encounter (like poor grounding). 
That's just part of being a good op."

To that I'll add my three rules for antennas:
***If you want to improve any antenna raise it higher.
***If you want a better antenna add more metal (more elements
     or longer wire and so on) as bigger is often better.
***Above all else put something up or toss a wire out the window
    on the ground floor, it will be better than a bucket of wire in the shed.
    And you will then have an antenna you can compare you future work to.

Allison