Date   

Re: 0.03w RF output, 1w at transistor drains, Help? #qcx

Shirley Dulcey KE1L
 

Thank you for this answer, W4JED. That's a point that a lot of us missed; we were assuming there is actually RF on the non-LPF side of C29. The suggestions people (including me!) have been making about C29 open or shorted capacitors in the LPF are correct if there is RF (which you can verify with an oscilloscope or an RF probe), but if there is little or no RF present you need to look elsewhere for the solution.


On Wed, Aug 19, 2020 at 8:50 AM James Daldry W4JED <jim@...> wrote:

PUH-LEEZE!!

When applied to a point with a DC voltage, the "wattmeter" reads the DC as "watts". Any DC voltage above a certain level (Hans could probably tell you what that level is) is read as 5.2 "watts". Meaning, any "watt" readings on the drains of Q1,2,3 are meaningless. It only tells you that the DC is getting there. If you were to touch the 12 volt input connection it would read 5.2 "watts". Look at the schematic. There is no blocking capacitor to keep the DC out of the A to D converter. Before C29, MEANINGLESS. After C29, sorta OK. At the antenna jack (where there is an actual sine wave) something like an actual reading, provided it is connected to a 50 ohm dummy load. Not an antenna, because the impedance of an antenna can be all over the place, and the reading will change with impedance.

73

Jim W4JED

On 8/18/20 8:57 PM, spam via groups.io wrote:
I'm measuring '5.2w' on the input of c29, and only 0.14w on the other side, I'm assuming this is not correct here


U3S + for sale

Podolsky A <w8du@...>
 

Mates:
I have the following for sale. 99 percent assembled but never powered up or aligned. Just don't have time for it. SO here is what I have:
U3s - Rev 3 F/W 3.12
GPS QLG1
Relay LPF board
LPF for 40, 30 20 meters (40 meter board not assembled)

Price is $50 plus actual shipping (USA sales only, no shipping outside USA)
Please send me an EMAIL to mycall at arrl d ot ne t if you want it.
Tnx de Arnie W8DU


Re: 0.03w RF output, 1w at transistor drains, Help

Jim Painter
 

Jim, good information. Thanks...

Jim...kq3s


On Wed, Aug 19, 2020 at 8:50 AM, James Daldry W4JED
<jim@...> wrote:

PUH-LEEZE!!

When applied to a point with a DC voltage, the "wattmeter" reads the DC as "watts". Any DC voltage above a certain level (Hans could probably tell you what that level is) is read as 5.2 "watts". Meaning, any "watt" readings on the drains of Q1,2,3 are meaningless. It only tells you that the DC is getting there. If you were to touch the 12 volt input connection it would read 5.2 "watts". Look at the schematic. There is no blocking capacitor to keep the DC out of the A to D converter. Before C29, MEANINGLESS. After C29, sorta OK. At the antenna jack (where there is an actual sine wave) something like an actual reading, provided it is connected to a 50 ohm dummy load. Not an antenna, because the impedance of an antenna can be all over the place, and the reading will change with impedance.

73

Jim W4JED

On 8/18/20 8:57 PM, spam via groups.io wrote:
I'm measuring '5.2w' on the input of c29, and only 0.14w on the other side, I'm assuming this is not correct here


Re: One more problem U3S WSPR

Vernon Matheson
 

You should read again John...copied and pasted from the assembly instructions.

Cheers

Vernon

On 2020-08-19 14:31, John McClun wrote:
From what I read in my build instructions, position 0 must have the highest band module.  In my case 10M (28Mhz).


Re: One more problem U3S WSPR

Roger Hill
 

Hi John:

No that is wrong.

Highest band goes in position 1. Read the manual carefully.

Regards

Roger

G3YTN

---
***************************
Roger Hill
***************************


On 2020-08-19 15:31, John McClun wrote:

From what I read in my build instructions, position 0 must have the highest band module.  In my case 10M (28Mhz).


Re: One more problem U3S WSPR

John McClun
 

From what I read in my build instructions, position 0 must have the highest band module.  In my case 10M (28Mhz).


Re: Alignment process

Brent DeWitt
 

I agree with Curt that the built-in bar graph works very well, but the auto-scaling can be a bit distracting.  as an alternative, I've found that simply listening with a decent pair of headphones allows me to null the adjustments pretty well.
-- 
73,
Brent DeWitt, AB1LF
Milford, MA


Re: One more problem U3S WSPR

Doug
 

Hi Ken
Thanks for your suggestion..... I monitored the 5 v line and I don't think it is dipping.
I think what I am going to do is order another relay board kit..... I am starting to think I have some faulty relays.
I do not see any other answer.... I could be wrong, but I figure if I build another relay board kit, there is nothing
else that could cause these problems. As I look at the wiring schematic, the five relays are attached to the five pins off the
MCU (ic-1)...It seems  straight forward....You can see my board... All the jumpers seem to be right. You can not see the diodes
in the picture, but I checked and they are on the board correctly.... The only other thing is the MCU, but I don't think that is the case. In fact, because
I wired those stranded wires directly to the transmit board and they tend to break when flexed much at all,, I am going to rebuild that kit and I will have a new MCU.... It transmits on 40 meters just fine and that is
the band I am most interested in, so I am fine for now.... But, I do want to try an figure out what went wrong here......
I want to thank everyone for your suggestions and time....I appreciate it very much.... Maybe I can return the favor in the future...
73's to all
Doug WA3ZHG


Re: 0.03w RF output, 1w at transistor drains, Help? #qcx

James Daldry W4JED
 

PUH-LEEZE!!

When applied to a point with a DC voltage, the "wattmeter" reads the DC as "watts". Any DC voltage above a certain level (Hans could probably tell you what that level is) is read as 5.2 "watts". Meaning, any "watt" readings on the drains of Q1,2,3 are meaningless. It only tells you that the DC is getting there. If you were to touch the 12 volt input connection it would read 5.2 "watts". Look at the schematic. There is no blocking capacitor to keep the DC out of the A to D converter. Before C29, MEANINGLESS. After C29, sorta OK. At the antenna jack (where there is an actual sine wave) something like an actual reading, provided it is connected to a 50 ohm dummy load. Not an antenna, because the impedance of an antenna can be all over the place, and the reading will change with impedance.

73

Jim W4JED

On 8/18/20 8:57 PM, spam via groups.io wrote:
I'm measuring '5.2w' on the input of c29, and only 0.14w on the other side, I'm assuming this is not correct here


Re: Using 5Watt PA on 6 and 2meters. #5wPA

Timothy Fidler
 

Phil
Tim in ZL back again.  As far as the OPT is concerned , I have had a look at optimising it  at 80 Mhz as a half way house between 6m and 2m. Type 43 material as per previous is death to RF at such frequencies. 
I came t the conclusion that a FT50-61 would do the job with 0.9 x the current winding scheme. This is based on real test data on coax suppression cores  , not just simple AL values.  This is on the basis of presenting to the Drain of the MOSFET the same approximate primary Z as it saw at 10 Mhz with the original FT50-43 core. I had to use some min frequency design basis and without calculations from the designer available to me 10 Mhz was a good number between  3 Mhz and 28 Mhz as a mean design point.  The data I used was based on Farrite Cat 14 datasheets and also the AL values shown on the Toroid King  technical pages.  These latter data relate to Amidon toroids I believe and  Am and Fairrite use the same material but different ID and through  dimensions for the same inch series cores.  Engineering basis in due course - written up in my diary. 


transmitter/transceiver idea

Jens Groh
 

Hello Hans and all,

what would you think of a QRPLabs "Transmitter Module"? Counterpart of the Receiver Module and a QSX spin-off.

We could combine the VFO Module, the Receiver Module, said Transmitter Module and appropriate filter modules, and this way have a complete transceiver frontend. Then connect it to a PC's sound port or alternatively to an audio-centric embedded system (my preferred one is Axoloti btw) and do the modulation/demodulation there.
This would open up QRPLabs transmitter technology to creators of experimental, new or "think different" operation and modulation modes, transceiver concepts and user interfaces.
For a classic SSB transceiver it is not necessary, of course. Simply wait for QSX and buy and build one.

The Linear PA Module, to support a transceiver frontend like that, should adopt the receiver bypass switch from the 50W PA and have the connections to the receiver section and the transmitter section separated.

Attractive or not?

Greetings
Jens

"Make Redefining Ham Radio Easy!" (imagined QRPLabs Motto;-)


Re: Power rating for LPF Kit? #lpf

Shirley Dulcey KE1L
 

There are three things that can limit the power handling of a filter:

1. Voltage rating of the capacitors
2. Saturation and heating of the cores
3. Resistive heating of the wire used to wind the inductors

To make a higher power filter you scale everything up. Higher voltage caps, larger cores, thicker wire. Also wider traces on the printed circuit board, and for a very high power filter you might also need to go to a PCB with a thicker layer of copper or wire it point to point. You can see an example of how you might scale up the LPF in the 50W amp kit; Hans uses 250V caps instead of 50V caps, T50 cores instead of T37 cores, and thicker wire to wind the toroids.

Hans got the design from W3NQN, who offered his designs freely to the ham community. You can build your own filters using the same design but with suitable components. Though if you only need a 10W filter, it's hard to beat the price of the kit from Hans!



On Wed, Aug 19, 2020 at 1:49 AM spam via groups.io <spam=craftxbox.com@groups.io> wrote:
Thank you! Out of curiosity, What are the factors that dictate this? How could I possibly increase the power they can handle?


Re: 0.03w RF output, 1w at transistor drains, Help? #qcx

Alan G4ZFQ
 

I'm measuring '5.2w' on the input of c29, and only 0.14w on the other side,
The problem is that the on-board power meter does not necessarily show RF here. DC voltage will affect this and make you think there is RF there.
Connect one end of your 104 capacitor to the input end of C29. See if the power meter reads anything on the other free end of the 104.

73 Alan G4ZFQ


Re: 0.03w RF output, 1w at transistor drains, Help? #qcx

jim
 

On further consideration ..Check for a ground on the RF connector ...through L1,2,3 ...(power off) any of the caps in the LPF could be shorted, C29 could be open ....simple ohm-meter check will verify

Jim

On Tuesday, August 18, 2020, 5:57:08 PM PDT, spam via groups.io <spam@...> wrote:


I'm measuring '5.2w' on the input of c29, and only 0.14w on the other side, I'm assuming this is not correct here


Re: 0.03w RF output, 1w at transistor drains, Help? #qcx

jim
 

unsure as to how you are defining "5.2 watts" at input of Q29...waveform at that point is CLK2 (gates of q1,q2,q3) swinging from Vcc to ground...A (nearly) Square wave...as such it is composed of the fundamental frequency (clk2) and LOADS of odd harmonics...any "power"  measured there will include ALL the power in the fundamental and ALL the harmonics...

IF you are defining power at that point as referenced to 50 ohms, be advised that at that point Z (impedance) will be most anything other than 50 ohms ...Drain on q1,q2,q3 all high Z....collector of Q6 high Z...Per Section 5.9 of the assembly manual L4/C30 resonate circuit for class E defines Z at that point ...as class E...maybe 50 ohms....maybe depending on value of L4 and C30 resonate frequency...

Have you double checked the values of the capacitors/inductors in that area? as they are band dependent,  maybe some/one got swapped/mis-labled

Jim




On Tuesday, August 18, 2020, 5:57:08 PM PDT, spam via groups.io <spam@...> wrote:


I'm measuring '5.2w' on the input of c29, and only 0.14w on the other side, I'm assuming this is not correct here


Re: Power rating for LPF Kit? #lpf

 

Thank you! Out of curiosity, What are the factors that dictate this? How could I possibly increase the power they can handle?


Re: One more problem U3S WSPR

KEN G4APB
 

Doug, it sounds like a PSU supply dipping problem to me. Try a large value electrolytic across your 5v line. 

73 Ken G4APB


Re: Power rating for LPF Kit? #lpf

Hans Summers
 

The Low Pass Filter kit can handle at least 10W safely.

73 Hans G0UPL 

On Wed, Aug 19, 2020, 06:00 spam via groups.io <spam=craftxbox.com@groups.io> wrote:
Hello, I'm wondering what the maximum power the LPF Kit's can take, Specifically for the 80m, 40m and 20m variants if they differ any.


Re: Using 5Watt PA on 6 and 2meters. #5wPA

Timothy Fidler
 

Phil for the  RD15HVf1 you will have to "twist the pins" on G  and S it is I believe . People who have made PCB drafting errors of this type have reported losses at HF NOT VHF  of 0.3 dB from this.  Error -the instructions say this was allowed for , I was thinking of the 10 W linear kit. Seems that this kit has a dual pad arrangement.

2. Deleted. 

3. Almost all high performance amps at VHF use PTFE insulated wire in their OPT cores.  IN fact a lot above 6m use 1/4 wave Coax TE transformers which is a big change and a hard to get bit of kit in small qty. This makes them only semi broad band. Delete comment on Coax transformers for a class C amp design. Refers to cl B PP.

4.  I believe this kit uses type 43 Ferrite cores nominally Yes , FT50-43.  That is magnificently lossy even at 15Mhz.  You  will be able to get type 61 to work at 6m This has been proven in many real designs. Typically a PPull amp using the RD16HH (nb sixteen) and  using type 61 OP cores will produce 8 W out on 6m when it produced 16 W out on say 20m .  your mileage may vary but be prepared for as low as say 3W out after changin out the ferrite.  The best solution is to use a type 61 ferrite which has the same AL as a single FT 50-43.  If you used an FT140-61 which is massive c'w the original  then you are still short on AL , 150 versus  440 for the previous part.  (see Kitsandparts or Toroid king website for this data ) Possibly the cleanest soln is two off FT114-61 stacked and epoxied  end to end for an AL of 150 now up the turns by root (440/150). That gives you a multiplier onturns of 1.7 which, looking at the photo is probably feasible.  Will a type -61 ferrite work at 150 Mh? .  The Fair rite catalogue 14 show data - see the multiaperture core page. For a type 61xx 202 core the indications are the core Will work at 150 Mhz - the XL has dropped only about 10 percent over the 50Mhz value but is going south rapidly to wards zero impedance.  THe equiv curve for a type 43 material core shows it unusable as a practical RF transformer  above 80 Mhz.




5. If you are to get this to work on 2 m then the BS170 will almost certainly require change out .

All the information on its DS indicate that performance above 50 Mhz is problematical .  Sod's law is that there is no equivalent really as an industrial (cheap item ) that will work well at 144 Mhz.  There are some RD06 devices you could look at -they are going to be expensive to get in one offs from a reputable supplier . All the datasheets for these Mitsi mosfets are on the RFParts  (USA) site. 

 RD15HVf1 with a small bias based on the standard 5V type of cct  (adjustable to about 2.4 VDC  ) which implies a coupling capacitor might be an easiest case (procurement ) replacement for the BS170. Or after looking at threshold voltages on the respective DS  and what the BS170 is currently seeing you might be able to do just a simple twisted pin replacement. This is not beautiful for VHF and you potentially could get all sorts of instability issues (happy thought for the evening ).  Gate inductors of three turns of Cu wire on a 100 ohm  Carbon resistor body have been known to help in that case (at HF- mileage may vary).

This sort of (analogue)  circuit potentially can produce 8 W RF when RD16HH is used at HF.  possibly you might go as close as 5 W at VHF with optimised components.  I have no idea if the drive cct can run at 144 Mhz. HC 595 - HCmos logic - 40 Mhz clock rings a bell. Are you running it with the AT Tiny 84 and how fast can that run it ??.  it sounds  to me that 144 Mhz might be a non starter on the digital side - perhaps the frequency comment in the text refers only to what the PA could do on the anal. side and with massive re-engineering.. ... over to you , pilot.





Power rating for LPF Kit? #lpf

 

Hello, I'm wondering what the maximum power the LPF Kit's can take, Specifically for the 80m, 40m and 20m variants if they differ any.