Hi Howard,?
OK on the short between rf out and ground, that is the same problem that I had.
Try putting the lpf relay board back in and then use only 1 filter, put it in position 1 and see if the short disappears. It may be that one of the lpf's has a short, mine did and it was the filter that was always in series.
Be aware that as the frequency increases, power output decreases. Try the 40m lpf and see what power it gives.
Another way to check the lpf's is to pull them from the board and check continuity, the two outermost pins on one end, doesn't matter which end, should be O/C, if there is continuity there is a short on that particular filter.
Good luck?
Andy.

I think we need to get this tag into use.
--
> I finally got it all together...now I can't remember where I put it<

Wes

AE6ZM

Hereford, AZ

?

I do not see where anyone has mentioned the W0-W1 and W2-W3 jumpers. Do you have the correct configuration?
--
> I finally got it all together...now I can't remember where I put it<

Wes

AE6ZM

Hereford, AZ

?

These were DC measurements on the bs170. I need to read about the RF probe, from the reference you sent me and then build or borrow one to make the measurements you are suggesting.?
Also, it was suggested that maybe I burned out the BS170, when the low pass relay board was in the circuit and caused a short between the RF out and ground? (now it out of the circuit)... but if I have these DC measurements now, it means that BS170 is still good. Yes?
Thanks again, for your time... we will solve the problem... (that's the spirit). I'll work on the problem during the week... in and around my volunteer work.
73 Howard 4x1zz

I was asked to check?the drain voltage (DC and RF) on the BS-170: I measured on receive 5.08 volts and on transmit I measured 5.17 volt. (Positive lead on the drain and negative lead on ground.)
At the Gate of BS170, on receive, I measured 1.84 volts and transmit 1.82 volts.
I hope this information is good, for your suggested next step to solving my very low RF power out.
Tnx for your time.

What about power consumption does it increase when transmitting?
Does the power consumption change at all when adjusting the bias?
If you had a short between ant and ground (I take it you had the same short between ground and RF in) you would probably destroy the PA fet.

Jan

I found that there is short between the RF out and ground when the Low pass relay board inserted. (I used the RF out and ground from the low pass relay board... also all the filters were in the proper order highest frequency to lowest from 1-5 with 0 being the lowest.)?
Sooo, I took off the low pass relay board and inserted the 20 Meter LP filter on the U3 board and went solo, connected the RF out and ground from the U3s board. I have now only a drop more power... the watt meter needle did move a tad... but still very very low RF.
??

Ted

The rig will NOT transmit in practice mode, in all other ways it will behave normally.

Always check that you have an good antenna or dummyload connected before powering up the OCX.

Jan

¿ªÔÆÌåÓý

Hi Ga?tan,
You are correct in what you say, the synthesiser reference crystal is 'freewheeling' during the message cycles.
The U3 firmware calibrates after the end of the TX cycle, there is no continuous calibration process.

Your observations on negative drift in one mode and positive drift on another is a result of the duty cycle of each mode,
Both directly heating the xtal and associated components by warming of the PA transistors etc and also the differing loading of power supplies and the synthesiser IC it's self.
The park mode can extend this loading during rest periods in between transmissions but it's still not identical to the duty cycle experienced in use.
(There is another comment in a later post that rest periods are unacceptable for a beacon? so although you may have experimented with park mode,
you may not be getting the best results possible if you do not allow a sufficient period of dead time in the park mode for pre-heating of the synthesiser IC.
However you will still battling against the drift effects of warming and cooling of the xtal and components.)
Based on the information you have provided,
Using a 20 second calibration after 3.5 minutes of key down you are asking the calibration routine to 'pull' back the xtal reference frequency back in line
while at the same time the physical xtal and osc components? are experiencing a cooling period as the PA is off.
it's a tough ask for everything to reach equilibrium in 20 seconds!

Good electronic and mechanical / thermal construction will help.
There is plenty already written on the subject of frequency stability FAQ and HOW to DO's,
mainly in response to QRSS and WSPR but equally applicable to use of the U3S in VHF.
The search function on the IO groups website will become your best friend.

Hans has already provided solder pads on the Si5351 synthesiser PCB for substitution of the crystal for a TCXO module.
A problem with using these components is that it should be remembered it is a Temperature Compensated Xtal Oscillator and not an 'old-fashioned' Temperature Controlled Xtal Oscillator.
The compensation aspect of the modern devices take the form of discreet frequency steps which will also show in the synthesiser output as the compensation temperature falls above or below each threshold.
(Some manufactures devices have larger frequency steps than others)
The better solution is to use Han's own OCXO synthesiser PCB, this works on the principle of holding the crystal and associated osc components at a higher temperature than what they are expected to experience during the TX cycle,
and has no undesirable frequency steps in use.


Just to manage expectations, a U3S will be OK for your own short term personal low power beacon use.
If it were intended to provide a national service, best check your countries radio authority publications as regards frequency accuracy & inband and out of band spectra,
and satisfy yourself you have the resources and are able to operate to those standards.
The U3S is good, it's very good, but it's still a below €30 item, and as such it's more than setting up the menu entry's and adding an additional PA and low pass filter.
It's perhaps not the first or easiest choice to base construction of an off the shelf beacon on.
That said, others have developed the progrock module to become a modern day replacement to a 96MHz reference & multiplied up for UHF / SHF working, given the resources it's possible.

Many VHF and up, beacons are increasing becoming based on the modules documented by OZ2M






I hope this is food for thought, regards Alan

? Just so I can learn about how to test with a DVM. I¡¯m hoping I can improve my troubleshooting skills so I can figure out for myself in the future.

FETs are not too easy to check with a meter, some hints were given in past posts. A component tester works and is a good thing to have.

The power amplifier and i think it¡¯s Q6 that needed to be

replaced too because I can¡¯t even power up the rig right now because it¡¯s stuck on TX or something like that,

Q6 is the TX 12V switching transistor, look at the schematic.
When Q1, 2, or 3 shorts then it does as well. So 12V remains applied to the shorted BS170(s)

if I plug it in it draws

overcurrent and burns up even more

Is the result.
If you just replace one defective device it starts all over again.

73 Alan G4ZFQ

Hi All
My USB tiny ISP will not see any of my 3 off QCX's MCU's
All 3 QCX's have been programmed and Re programmed using the ISP at some time i.e from Firmware V 1.00 b to e.
As I thought maybe the ISP had failed I ordered another one but that performs the same.

Two of the QCX's are using 25MHz xtals I have a firmware file to accommodate the 25MHz and one is still using 27Mhz
All 3 are at version 1.00e

Because I lost one of the MCU's which was at 25MHz I ordered another from Hans which arrived at v1.00e programmed for 27MHz.

I need to re programe it with my 25MHz version. Now I am at a loss as to what the problem may be!

Has anyone tried to re program? an MCU which is already at ver 1.00e? with success?

I am using AVRDUDESS and have tried Bitburner they both come back with the same error

avrdude.exe: initialization failed, rc=-1

¿ªÔÆÌåÓý

I live in harmony with a 22kW AM station, but it's 3km away, not a mere .25 miles!

A couple of things:
1)? I see a model; 402X ICE BCB filter - it has a ground lug.? Have you attached a ground at that point?
2)? I'd try an attenuator in the antenna line, just to see if the QCX receiver is being over-loaded.? Sometimes,
just a few dB of attenuation will make the problem go away.
3)? Have you other rigs/antennas that manage to survive the onslaught of a BC station that close?
4)? I use an L-network with the inductor as the shunt element - this allegedly provides a high-pass response.
???? Do you use an antenna coupler of any kind (including internal couplers on other rigs)?
5)? It might be a common-mode issue - have you tried a balun or some kind of choke right at the rig?
???? Like a dozen turns of RG-174 around a type 43 core?
???? If it was common-mode, I can envision a case where the RF would flow around your filter.

Good luck
Jerry
KI4IO

Have you read the FAQ about frequency drift?
The GPS will not help against short term frequency drift, but the different parking modes might (there was a good discussion here a while ago about the drift and parking).
If you have the new rev synth board there is provision to mount a TXCO I think that would solve your problem.

Jan

2nd harmonic would be on 3080 4th harmonic would be on 6160 and 5th on 7700 normally it is the odd harmonics that are much stronger, so my guess is it is not a harmonic (could be some other mixer product).

Have you the QCX in a metallic box ?
If you disconnect the antenna is the AM station still there?

Jan

What is the configuration that needs to be changed?

Ted

Eventually found this, not emphasised enough!

/g/QRPLabs/message/21033

73 Alan G4ZFQ

You need to set menu 4.7 Practice to ON.

The manual clearly states why GPS and paddle are in parallell (5.14).

Jan

What is the configuration that needs to be changed?

It's somewhere in the manual, I guess it's easy to miss. The GPS input is shared by the keyer so something needs to be changed.

I guess always have an antenna connected just in case.

Or dummy load. A mis-matched antenna could be almost as bad as none.

73 Alan G4ZFQ