Date   
Re: 50w amp

Curt M.
 

I use a switchable multiband low pass filter for one of those 75w eBay amplifiers and the output looks great. No reason you can’t use something like this. Not sure if they are still available on eBay or not. This is before I installed everything in a nice metal enclosure  


Curt M.

Re: 50w amp

Andy Brilleaux <punkbiscuit@...>
 

For +general+ info, an Atu typically adds 10 to 15db of harmonic attenuation, depending upon loaded Q.

Useful in its own right, but not a, replacement for having the right lpf in the first place.


73 de Andy

Re: QCX alignment aid #alignment

Trystan G0KAY
 

I've not realigned my QCX since I made it. Seeing the stickers makes me wonder if I should be realigning it from time to time?

Re: 50w amp

KEN G4APB
 

Hi Alan,
I used to use the valve transmitter ‘Tune and Load’ in band switchable pi networks and no tvi filter, but had an ATU. I wonder if that system simply matched tx to antenna or actually provided sufficient harmonic filtering? We seem to have lost some  of this knowledge in the quest for broadband ‘no adjustment’ rigs.
73 Ken g4apb 

Re: 50W PA for QCX Arriving in the US

Andy V. Borisenko
 

Don, I had a K-2 for several years. With all the options.
This is a highly publicized transceiver, but in fact an ordinary radio. A lot of myths and legends around K2. Best for CW, etc. This is not always true. When you buy and collect it, remember my words.
Please note: poor quality components. Take a few variable resistors in addition to replace them (af / rf gain, after a year of operation).
And never buy the KIO2 option! This will give CAT, but also S+2 noise.
K2 is not protected from static in any way. Be careful.
And to correctly configure CW filters (so that they work on the same frequency) is from the realm of fantasy.
Think Don. And good luck!

Re: MSF or DCF clock module instead of GPS

Alan G4ZFQ
 

I wish there would be some solution out there for using the DCF77
Razvan,

In principle it is simple, decode DCF77, convert it to a NMEA stream.
Or a hardware solution would be to produce the 20MHz reference from an OCXO. A good OCXO could keep very good time.
Or lock it to the DCF carrier?

73 Alan G4ZFQ

Re: MSF or DCF clock module instead of GPS

Arv Evans
 

Rasvan. DL2ARL

It might be a better approach to regard the U3 as hardware only, and write your own complete software suite.  This avoids the whole proprietary software issue.

Arv. K7HKL



On Fri, Jan 3, 2020, 6:03 PM <dl2arl@...> wrote:
I wish there would be some solution out there for using the DCF77 and someone would post it here. General hints regarding solutions for DCF77 clocks made on the basis of popular microcontrollers help of course, but are not the final goal I was aiming towards. I need a solution for the U3 and this has little to do with a simple and stand alone DCF77 clock.
Even if I would devise a way to decode the DCF77 data stream somehow (information galore on the net), I would still need help in order to know how to inject it into the U3 logic, which is not an open source project.

Have a great New Year and all the best to you!

73, Razvan DL2ARL

Re: MSF or DCF clock module instead of GPS

dl2arl@...
 

I wish there would be some solution out there for using the DCF77 and someone would post it here. General hints regarding solutions for DCF77 clocks made on the basis of popular microcontrollers help of course, but are not the final goal I was aiming towards. I need a solution for the U3 and this has little to do with a simple and stand alone DCF77 clock.
Even if I would devise a way to decode the DCF77 data stream somehow (information galore on the net), I would still need help in order to know how to inject it into the U3 logic, which is not an open source project.

Have a great New Year and all the best to you!

73, Razvan DL2ARL

Re: 50w amp

@CurtisM
 

No that was Skip's comment not mine, but we had the same theme.

Add me to the confused, when Ron mentions a multiband LPF. Is this a set of filters, selected with a switch or relay?  do insure they can handle 50 watts. Many cannot.

Curt

Re: 50w amp

geoff M0ORE
 

A LPF is needed to primarily attenuate harmonics. A square wave signal is primarily odd harmonics with the third being the dominate. This means that a 7MHz square wave will have a significant output on 21MHz. To attenuate this signal, a 30MHz cutoff LPF is as much use as a chocolate teapot. 
A  LPF needs to have a cutoff just higher than the signal you want to pass. For 7MHz, something about 7.5MHz would be OK.


Re: 4 line display for qrplabs clock

Bobby
 

Jim,

Hi!  Purchased mine fro Adafruit.  Good price.  Works great.  See attached photo.  Click link to see product.


73
W2RWM
Bob.....


-----Original Message-----
From: Roy Edens <rjedens@...>
To: QRPLabs <QRPLabs@groups.io>
Sent: Fri, Jan 3, 2020 4:53 pm
Subject: [QRPLabs] 4 line display for qrplabs clock

I am building my second clock and would like to use 4 line display. I would appreciate information on a suitable display--Model/part number and source.
Jim w6rjq

4 line display for qrplabs clock

Roy Edens
 

I am building my second clock and would like to use 4 line display. I would appreciate information on a suitable display--Model/part number and source.
Jim w6rjq

Re: 50w amp

Alan G4ZFQ
 

Traditional lpf were intended to limit TVI...on the transmit.
Modern lpfs are used to limit the RF into SDR rxes.
Once upon a time we had valve (tube) transmitters that had tuned outputs and did not radiate too much harmonic power. Then a 30MHz LPF was normally adequate in order to avoid TVI.
Now we have wideband amplifiers that produce a relatively high level of harmonics and need much tighter LPF suppression to avoid creating QRM on higher bands. Especially class C, D, E might need one for each band.

73 Alan G4ZFQ

50w amp... pse excuse my error

SkipF, NT1G <skip.flem@...>
 

Modern lpfs on cqx 'softens' the square wave transmitted.
The traditional lpf is much too high in cut off to prevent a 20 M
signal from blasting 10m.
If the amplifier is a 'linear amplifier'...it needs an analog (lpf)
 input. Why amplify harmonics?


On Fri, Jan 3, 2020, 3:50 PM SkipF, NT1G via Groups.Io <skip.flem=gmail.com@groups.io> wrote:
Traditional lpf were intended to limit TVI...on the transmit.
Modern lpfs are used to limit the RF into SDR rxes.

Re: 50w amp

rentwist@...
 

On Fri, Jan 3, 2020 at 12:13 PM, @CurtisM wrote:
Traditional ham LPFs only reject signals above 30 MHz
@Curt, agree with all you wrote, but the above is very confusing , at least to me.  Perhaps clarification is in order.  By "Traditional", you must mean a TVI filter, correct?

For a PA LPF, this is simply not true.  If it were, only one LPF would be needed for all HF bands!

73,

Robert, WA2T

73,

Robert, WA2T

Re: 50w amp

SkipF, NT1G <skip.flem@...>
 

Traditional lpf were intended to limit TVI...on the transmit.
Modern lpfs are used to limit the RF into SDR rxes.

Re: QCX alignment aid #alignment

Curt M.
 

Very good idea.  Next time I open mine up, I'll have to do that.

Curt M.

Re: Smoked my 40

George Korper
 

DO NOT REPLACE THE BS 170'S UNTIL YOU CHECK THE VOLTAGES
ON THE PINS.IN THE TRANSMITTING CIRCUIT.  THEY ARE IN THE MANUAL. 
I REPLACED THE FINALS
THINKING THE PROBLEM WAS SIMPLE AND THEY BLEW AGAIN
WHEN IT WAS A PROBLEM THAT WAS IN Q6 AND IC3 AS WELL. 


On Fri, Jan 3, 2020 at 1:47 PM Jon R Garber <kc8rlp@...> wrote:
Well dang, I smoked my QCX 40. I was going to operate WSPR. I connected my GPS to the radio, and while attempting to set the programming all of a sudden smoke started to pour out from underneath the display. Now there is no power out of the rig. 

Re: Smoked my 40

N3MNT
 

Several questions.  Did you have a reasonably tuned antenna connected?  What version of the firmware were you running?  In earlier firmware revisions if the GPS was connected to the QCX with power connected, the transmitter would be keyed as the gps inputs and the key inputs share a common pin.  The last two revisions of the firmware disable the tx if GPS connected and not in beacon mode.  Most likely you damaged the 3 final transistors and the driver.  This is not uncommon.

Re: Smoked my 40

Gregg Myers
 

Sorry, my mistake. I read more carefully it was the GPS that transmitted as I read your message again. If you upgrade the firmware to 1.03 that won’t happen, as it will automatically put the QCX in Practice mode with GPS connected. Are you on earlier firmware?
73, Gregg

On Fri, Jan 3, 2020 at 1:05 PM Gregg Myers via Groups.Io <gregg.w7grm=gmail.com@groups.io> wrote:
Hi Jon,
You likely just smoked the RF Finals, Q1, Q2, and Q3. Hopefully, just those. They are underneath the display where you saw smoke. I think you can repair easily enough. I guess you had no antenna or dummy load connected as a WSPR transmission with no load can do that!
73,
Gregg

On Fri, Jan 3, 2020 at 11:47 AM Jon R Garber <kc8rlp@...> wrote:
Well dang, I smoked my QCX 40. I was going to operate WSPR. I connected my GPS to the radio, and while attempting to set the programming all of a sudden smoke started to pour out from underneath the display. Now there is no power out of the rig.