Date   

Re: 50 watt amp problem

m0bmn
 

Hi Andrew
Thanks for taking the time to reply, i think you mis-understand my comments on the bias current, with the pot turned fully anticlockwise the voltage on the gates of the fets is zero and the amp draws 40mA with the PTT line enabled of course, now my own amps draw about 80mA under the same conditions.  that's what seems strange to start with, as the pot is advanced the current at about mid point starts to rise as the voltage on the gates increase.  The 4k7 pot it self draws about 10mA (5v/4.7K= approx 10mA) so its possible I suppose that 40mA is OK  at this stage.
Its a fair and good point about the diodes, I have NOT the correct diode fitted (D7) , so its possible that could be the root of the low power??? I have ordered some diodes from RS so should be here Monday /Tuesday , I hope that makes a difference. at least its giving 'some' RF now , before it was zero.
also a good point about the transformers, that is a possibility, I will , if the diode swap doesn't help remove them and rewind. This is turning into a bigger job than I expected, that will teach me to offer help Hi.
once i fit the new diodes i will report back.

Thanks again for the time and trouble.
73 for now
Paul M0BMN


#40m #40m

Don Blachura
 

Just wanted to say what a amazing lil rig the QCX plus is.
This morning on the "OC" contest on 40 meters cw, using my ground mounted vertical and 4
 watts worked  "Australia" from Lake View, NY. ( near Buffalo,NY ).

Don...w2xb


Re: #gps #gps

Greg Walters
 

I'm with Hans,

I have my clock set up with the QLG1 and can connect quite easily to 9-13 satellites. Mind you, it is located on the bottom floor of a split level house, with a metal roof. Yes, it is about 3 feet from a window, but that window opens up under the metal roof of our parking area. No issues receiving signals. 

I'm also contemplating a WSPR setup... I'll be curious of what you end up with, Rick. 

Keep us posted. 
--
73,
Greg
KY4GW


Re: #gps #gps

Jim Mcilroy
 

Hi

Sometime in the last century when GPS receivers were the weight of boat anchors I had a task to fit a GPS antenna on the roof of a 9-storey building and cable it to an apparatus room in the basement where the 1pps signal from the receiver would keep a rubidium oscillator tame.

I used air spaced dielectric cable and big chunky N-type connectors. No repeaters.

It worked well.

In the UK you can get this stuff from Westlake Cables. Don't know about the USA but I'm sure somebody has it.

73

Jim

G4EQX

On 10/10/2020 12:01, Shane Justice wrote:
Hi Alan,

I have heard of a passive repeater, but I wouldn't expect them to have much performance, much as it sounds like you have experienced. For what it's worth, there was a period of time where cell boosters were marketed as boosting cell phone performance in rural areas. I've never known anyone to try them.

In professional use, I have seen active GPS amplifiers used indoors, such as in a large conferences where many gps equipped systems were being demonstrated, but that is the limit of my experience in that arena. Unless I had multiple GPS units that had to work in an area indoors where there is poor signal, it is more cost effective to use an external amplified antenna to bring the signal in to the GPS unit. The position fix reported by the GPS will the t-e location of the antenna, not the location of the GPS receiver, if that is of concern.

Best,
Shane


On Oct 10, 2020 at 00:36, Alan G4ZFQ <alan4alan@...> wrote:

> Hense my assertion that the modern receivers are so sensitive that they

> may not need an amplified antenna in some situations.



Shane,



Yes, I've seen lots of reports here of reception in seemingly impossible

places.



But I've tried repeater antennas and they have only worked when nearly

on top of the RX antenna. Maybe I've not done it correctly and that's

not typical?



73 Alan G4ZFQ














Re: 50 watt amp problem

Andrew Lenton
 

Hi Paul,

 

Ok, this if a very simple circuit and little to go wrong providing it is correct in the fist place.

 

·       1st issue “I am only seeing about 40mA bias and that doesn't seem right.” The bias 5 Volt regulator is connected to a 4K7 pot 5V  divided by 4k7 = 1/940th of an Amp or 64mA, if you only get 40mA the pot cannot be 4K7 or the Bias supply is not 5V.

·       Having said that the pot is not a critical value it just need to provide a small bias voltage to the RF power transistors, so set to the point that increases the conduction and then drop back.

·       1N 4007, these are not PIN diodes, however, they work very well as RF switches, Elecraft used these in the K2 100 watt PA and the K2, I discovered not all 1N4007 are the same, with regard, as being used as RF switches, so changed them  for known good ones, same has Han’s supplies. I found this to my cost in repairing by K2 after a lightning strike, the replacement 1N4007 I had laying around did not work, but replacing them with a different make worked fine, I even swapped them back as I could nor believe it, they measured fine.

·       Apply 3 Watt and 15 V then let me know what power you are getting and the current consumed, on a good amp and then the troublesome amp, forget scopes and measure on a Watt meter, or Hans’s dummy load

·       Transformers, might be best to rewind them, if you have internal shot due to insulation failure on the same winding, the DC will be fine and the resistance close to the non-shorted value, however it will dampen the RF!

 

73

 

Andrew G8UUG


Re: #gps #gps

Shane Justice <justshane@...>
 

Hi Hans,

Thank you for the detailed, behind the scenes information on the QLG-1 design. I know the stitching of the ground plane instantly struck me when I looked at the PCB. It's a very nice piece of work. I actually found some higher inductance chokes to use, with the resistor and board-mount SMA connector and have that QLG-1 configured for inside-the-chasis mount in the U3S Deluxe case. I'm impressed with the performance of the system!

As I am in Arizona, I can attest that the sun out here is more harsh than most any other region in the United States, with the possible exception of the Death Valley region of the Southwest. Plastic, unless it is specifically UV stabilized plastic doesn't last long in full sunlight here. Even cars that have plastic materials for door handles have those parts fail after 8 or 10 years when kept outdoors continuously.

Sorry I missed your live chat the other night. I did happen to watch you video the next day with great interest. I enjoyed your presentation of the history of you and QRP-Labs. 

Have a great Saturday!

73,
Shane


On Oct 10, 2020 at 01:32, Hans Summers <hans.summers@...> wrote:

Hi Shane

Yes the modern GPS chips are very sensitive. However there's also magic in the QLG1 GPS kit antenna... the reason the QLG1 GPS PCB is so "big" compared to other GPS modules is intentional, the large groundplane under the patch antenna greatly improves the antenna performance and therefore overall sensitivity. The patch antenna is also custom-manufactured for QRP Labs and is sized and tuned to match the requirements of the PCB groundplane; I sent the factory assembled QLG1 PCBs and they figured out the exact size and tuning for the antenna to be perfectly resonant on 1575MHz. So the high sensitivity of the QLG1 GPS is due both to the sensitive GPS receiver chip and also the PCB design and antenna matching. 

Generally people should try the QLG1 with its own patch antenna. In my applications it will work well. I don't find any need to operate it with a clear sky view etc., it works fine indoors. 

I've never used an active external antenna with it but the PCB is designed to take an SMA socket for people who want to do that, and they also need to fit an inductor and resistor; note that the quoted 27nH inductance should be viewed as a minimum, not an exact requirement. So almost anything goes. Wind some wire around a high value resistor and you've done it in 30 seconds. No need to fuss over finding exact 27nH inductors. 

In Tokyo I used to have the GPS outside the window on the railings outside the window, and I ran about 10 meters of 4-conductor cable (shielded/screened cable) to the shack. It always worked fine. Even though since I was on the 3rd floor of 7, and with lots of tall buildings all around, there wasn't much sky view. I haven't tried more than 10 meters distance between QLG1 and U3S/QCX/etc. 

Note that when using common plastic food containers as an enclosure, be careful: the sun is a pretty harsh foe... several times I left things for 6 months, a year... then went back to check and as soon as I touched the plastic tub, it fractured instantly into hundreds of tiny fragments. Strong UV decomposes some plastics quite fast. Depends on where you live too... Tokyo has a lot of sunshine 80-90% of days and strong. Turkey too where I live now. The food containers would last longer in England :-)

73 Hans G0UPL 
http://qrp-labs.com 

On Sat, Oct 10, 2020, 06:00 Shane Justice <justshane@...> wrote:
Alan,
While I was waiting for the inductor to supply power to the active antenna, I hooked that antenna up to the QLG-1, and much to my amazement, the gps got a full 3D solution and this was inside my house with a 15 foot deep overhang over the full length patio.

Hense my assertion that the modern receivers are so sensitive that they may not need an amplified antenna in some situations.


On Oct 9, 2020 at 13:43, Alan G4ZFQ <alan4alan@...> wrote:

> GPS signal levels are quite low, but has anybody considered a "passive

> repeater" in the form of inside and outside tuned antennas connected by
> a low-loss coupler?

The problem is that the coax is not low loss. An active antenna is required.
So you may as well just use an active antenna.

73 Alan G4ZFQ







Re: #gps #gps

Shane Justice <justshane@...>
 

Hi Alan,

I have heard of a passive repeater, but I wouldn't expect them to have much performance, much as it sounds like you have experienced. For what it's worth, there was a period of time where cell boosters were marketed as boosting cell phone performance in rural areas. I've never known anyone to try them.

In professional use, I have seen active GPS amplifiers used indoors, such as in a large conferences where many gps equipped systems were being demonstrated, but that is the limit of my experience in that arena. Unless I had multiple GPS units that had to work in an area indoors where there is poor signal, it is more cost effective to use an external amplified antenna to bring the signal in to the GPS unit. The position fix reported by the GPS will the t-e location of the antenna, not the location of the GPS receiver, if that is of concern.

Best,
Shane


On Oct 10, 2020 at 00:36, Alan G4ZFQ <alan4alan@...> wrote:

> Hense my assertion that the modern receivers are so sensitive that they

> may not need an amplified antenna in some situations.

Shane,

Yes, I've seen lots of reports here of reception in seemingly impossible
places.

But I've tried repeater antennas and they have only worked when nearly
on top of the RX antenna. Maybe I've not done it correctly and that's
not typical?

73 Alan G4ZFQ







Re: #gps #gps

Hans Summers
 

Hi Shane

Yes the modern GPS chips are very sensitive. However there's also magic in the QLG1 GPS kit antenna... the reason the QLG1 GPS PCB is so "big" compared to other GPS modules is intentional, the large groundplane under the patch antenna greatly improves the antenna performance and therefore overall sensitivity. The patch antenna is also custom-manufactured for QRP Labs and is sized and tuned to match the requirements of the PCB groundplane; I sent the factory assembled QLG1 PCBs and they figured out the exact size and tuning for the antenna to be perfectly resonant on 1575MHz. So the high sensitivity of the QLG1 GPS is due both to the sensitive GPS receiver chip and also the PCB design and antenna matching. 

Generally people should try the QLG1 with its own patch antenna. In my applications it will work well. I don't find any need to operate it with a clear sky view etc., it works fine indoors. 

I've never used an active external antenna with it but the PCB is designed to take an SMA socket for people who want to do that, and they also need to fit an inductor and resistor; note that the quoted 27nH inductance should be viewed as a minimum, not an exact requirement. So almost anything goes. Wind some wire around a high value resistor and you've done it in 30 seconds. No need to fuss over finding exact 27nH inductors. 

In Tokyo I used to have the GPS outside the window on the railings outside the window, and I ran about 10 meters of 4-conductor cable (shielded/screened cable) to the shack. It always worked fine. Even though since I was on the 3rd floor of 7, and with lots of tall buildings all around, there wasn't much sky view. I haven't tried more than 10 meters distance between QLG1 and U3S/QCX/etc. 

Note that when using common plastic food containers as an enclosure, be careful: the sun is a pretty harsh foe... several times I left things for 6 months, a year... then went back to check and as soon as I touched the plastic tub, it fractured instantly into hundreds of tiny fragments. Strong UV decomposes some plastics quite fast. Depends on where you live too... Tokyo has a lot of sunshine 80-90% of days and strong. Turkey too where I live now. The food containers would last longer in England :-)

73 Hans G0UPL 


On Sat, Oct 10, 2020, 06:00 Shane Justice <justshane@...> wrote:
Alan,
While I was waiting for the inductor to supply power to the active antenna, I hooked that antenna up to the QLG-1, and much to my amazement, the gps got a full 3D solution and this was inside my house with a 15 foot deep overhang over the full length patio.

Hense my assertion that the modern receivers are so sensitive that they may not need an amplified antenna in some situations.


On Oct 9, 2020 at 13:43, Alan G4ZFQ <alan4alan@...> wrote:

> GPS signal levels are quite low, but has anybody considered a "passive

> repeater" in the form of inside and outside tuned antennas connected by
> a low-loss coupler?

The problem is that the coax is not low loss. An active antenna is required.
So you may as well just use an active antenna.

73 Alan G4ZFQ







Re: #gps #gps

Ian VA7ITM
 

On Fri, Oct 9, 2020 at 10:34 AM, N3MNT wrote:
I am thinking entire GPS outside ( in waterproof container ( even tupperware) and run 4 conductor shielded signal cable into shack.
At the very bottom of https://www.qrp-labs.com/qlg1.html is an example waterproof case.

73 Ian VA7ITM


Re: Clock - Day of the Week Problem? #clock

Kevin Luxford
 

Nigel,
Thanks for the advice - appreciate it.
vy 73, Kevin VK3DAP / ZL2DAP  ex VK6UI
--
Kevington


Re: #gps #gps

Alan G4ZFQ
 

Hense my assertion that the modern receivers are so sensitive that they may not need an amplified antenna in some situations.
Shane,

Yes, I've seen lots of reports here of reception in seemingly impossible places.

But I've tried repeater antennas and they have only worked when nearly on top of the RX antenna. Maybe I've not done it correctly and that's not typical?

73 Alan G4ZFQ


Re: Unable to Align my QCX+ CW Transceiver

Shane Justice <justshane@...>
 

Michael, I'm just getting back to the QCX+, and it appears that the big iron can burn off that enamel coating at 704 F, and in only a few seconds!

Best Regards,
Shane


On Oct 8, 2020 at 22:24, Michael Greene <kn6ize@...> wrote:

BTW, I had great luck burning the coating off of the wire that came with the main kit assembly, but found it impossible even at high heat to burn off the coating on the band specific toroid wire (seemed darker and thicker). I had to desolder those and scrape the wire end coating off with sandpaper.


Re: #gps #gps

Shane Justice <justshane@...>
 

Apparently.


On Oct 9, 2020 at 14:16, Arv Evans <arvid.evans@...> wrote:

Apparently you missed the point of my suggestion.
_._


On Fri, Oct 9, 2020 at 1:57 PM Shane Justice <justshane@...> wrote:
Arv,

These modern receivers have such a low noise floor that an amplified antenna is not required in an open sky situation. The amplified antenna is just extra insurance for situations where the are sky obstructions, and/or limited sky views available (think urban canyons, tunnels, and the like).

All the good, current receivers take all this into account in their signal processing chains, and you get this for the cost of the unit. The external antennas all come with weatherproof cables with connectors installed, ready to be threaded onto the socket on the board. 

In contrast, putting the whole GPS in a tupperware box, to be mounted outside in the weather, and bring in TTL level signals in the "shack" through a cable, is putting a lot more effort into accomplishing the goal of getting GPS data into the U3S/QCX/etc. You'll have to deal with a thicker cable, additional connections, RF noise injection on the TTL lines, and the poor signal levels of TTL over 5 or more feet, for starters. Unless you just like fiddling with stuff, getting a pre-made external GPS antenna and cable is the fastest, least trouble-prone, most efficient way to get the GPS data into the receiver.

I suppose it all boils down to your personal tradeoffs between using your time, spending your money, and your perceptions of what provides you with the greatest sense of accomplishment.

I prefer conquering a problem and having it stayed conquered for many, many years. I care about establishing a capability and being able to build upon that capability toward some goal, then moving on to the next challenge, the next capability, the next function, not continuously fighting with problems created by missteps with earlier, suboptimal implementations that require recurring maintenance/repairs.

It all depends upon what you want from your projects.

73,
Shane
KE7TR




On Oct 9, 2020 at 11:44, Arv Evans <arvid.evans@...> wrote:

GPS signal levels are quite low, but has anybody considered a "passive repeater" in the form of inside and outside tuned antennas connected by a low-loss coupler?
_._


On Fri, Oct 9, 2020 at 11:34 AM N3MNT <bob@...> wrote:
I am thinking entire GPS outside ( in waterproof container ( even tupperware) and run 4 conductor shielded signal cable into shack.


Re: #gps #gps

Shane Justice <justshane@...>
 

Alan,
While I was waiting for the inductor to supply power to the active antenna, I hooked that antenna up to the QLG-1, and much to my amazement, the gps got a full 3D solution and this was inside my house with a 15 foot deep overhang over the full length patio.

Hense my assertion that the modern receivers are so sensitive that they may not need an amplified antenna in some situations.


On Oct 9, 2020 at 13:43, Alan G4ZFQ <alan4alan@...> wrote:

> GPS signal levels are quite low, but has anybody considered a "passive

> repeater" in the form of inside and outside tuned antennas connected by
> a low-loss coupler?

The problem is that the coax is not low loss. An active antenna is required.
So you may as well just use an active antenna.

73 Alan G4ZFQ







Re: #gps #gps

Shane Justice <justshane@...>
 

Very good! I was going to comment that buying a piece of Tupperware alone would cost more than the amplified GPS antenna and the parts to integrate into the QLG-1...

Good job there!

Shane


On Oct 9, 2020 at 12:50, Frank W1FRA <allenfr@...> wrote:

There are always more proper ways to do something. My inexpensive, ie cheap, Tupper ware from the recycling at the dump, and 40ft of twisted pair of the telephone service truck works fine. Is it perfect Darned if I know, its always worked and I'm on to other projects !


Re: #gps #gps

Michael.2E0IHW
 

On 09/10/2020 21:42, Alan G4ZFQ wrote:
GPS signal levels are quite low, but has anybody considered a "passive repeater" in the form of inside and outside tuned antennas connected by a low-loss coupler?
The problem is that the coax is not low loss. An active antenna is required.
So you may as well just use an active antenna.

73 Alan G4ZFQ
The passive idea can work for mobile phones.
Yagi outside on a pole, low-loss coax to  inside dipole.
Hold mobile phone close for indoor use.

Michael 2E0IHW


Re: Clock - Day of the Week Problem? #clock

Daniel Walter
 

Correction: 1.03c firmware 
--
73, Dan  NM3A


Re: #gps #gps

Arv Evans <arvid.evans@...>
 

I think that you also missed the point of my suggestion.  
Using just inside and outside antellas with just a low-los
bulkhead connector through the wall might be worth testing.

Arv
_._


On Fri, Oct 9, 2020 at 2:43 PM Alan G4ZFQ <alan4alan@...> wrote:
> GPS signal levels are quite low, but has anybody considered a "passive
> repeater" in the form of inside and outside tuned antennas connected by
> a low-loss coupler?

The problem is that the coax is not low loss. An active antenna is required.
So you may as well just use an active antenna.

73 Alan G4ZFQ







Re: #gps #gps

Arv Evans <arvid.evans@...>
 

Apparently you missed the point of my suggestion.
_._


On Fri, Oct 9, 2020 at 1:57 PM Shane Justice <justshane@...> wrote:
Arv,

These modern receivers have such a low noise floor that an amplified antenna is not required in an open sky situation. The amplified antenna is just extra insurance for situations where the are sky obstructions, and/or limited sky views available (think urban canyons, tunnels, and the like).

All the good, current receivers take all this into account in their signal processing chains, and you get this for the cost of the unit. The external antennas all come with weatherproof cables with connectors installed, ready to be threaded onto the socket on the board. 

In contrast, putting the whole GPS in a tupperware box, to be mounted outside in the weather, and bring in TTL level signals in the "shack" through a cable, is putting a lot more effort into accomplishing the goal of getting GPS data into the U3S/QCX/etc. You'll have to deal with a thicker cable, additional connections, RF noise injection on the TTL lines, and the poor signal levels of TTL over 5 or more feet, for starters. Unless you just like fiddling with stuff, getting a pre-made external GPS antenna and cable is the fastest, least trouble-prone, most efficient way to get the GPS data into the receiver.

I suppose it all boils down to your personal tradeoffs between using your time, spending your money, and your perceptions of what provides you with the greatest sense of accomplishment.

I prefer conquering a problem and having it stayed conquered for many, many years. I care about establishing a capability and being able to build upon that capability toward some goal, then moving on to the next challenge, the next capability, the next function, not continuously fighting with problems created by missteps with earlier, suboptimal implementations that require recurring maintenance/repairs.

It all depends upon what you want from your projects.

73,
Shane
KE7TR




On Oct 9, 2020 at 11:44, Arv Evans <arvid.evans@...> wrote:

GPS signal levels are quite low, but has anybody considered a "passive repeater" in the form of inside and outside tuned antennas connected by a low-loss coupler?
_._


On Fri, Oct 9, 2020 at 11:34 AM N3MNT <bob@...> wrote:
I am thinking entire GPS outside ( in waterproof container ( even tupperware) and run 4 conductor shielded signal cable into shack.


Re: #gps #gps

Alan G4ZFQ
 

GPS signal levels are quite low, but has anybody considered a "passive repeater" in the form of inside and outside tuned antennas connected by a low-loss coupler?
The problem is that the coax is not low loss. An active antenna is required.
So you may as well just use an active antenna.

73 Alan G4ZFQ