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Re: Thoughts on Low Power and fewer turns on LP filter toroids

Brian George
 

Just a passing thought ...if component tolerances are a key factor contributing to low output when using the 20m and 30m LPFs then why aren't about 50% of constructors having to ADD turns and why is it only on 20m and 30m? I had exactly the same issue but a VNA scan showed that the 3dB cut-off points were ideal for both 20m and 30m - about 11% above the highest operating frequency. What I did discover was that the insertion loss was a little higher on the 20m LPF and the passband on the 30m LPF sloped down towards the cut-off pojnt instead of being flat. 

73
Brian
G3ZOH  


Low Pass Filer Board Timing. #bpf #wspr #u3s

Phil Crockford <pcc@...>
 

Does anyone have a definitive answer to the following: -

What is the time delay between the activation of a selected low pass filter, via B0-B5 from the U3S board, and the start of a WSPA transmission?

Thanks

 

Phi G8IOA


Re: U3S Output #u3s

Phil Crockford <pcc@...>
 

Yes I have done it. It involves a board with relays driven from the B0 - B5 outputs on the U3S board. Each relay controls the amount of Bias on the PA transistor via a potentiometer, one for each of the outputs.
It works well. If you want diagram and notes let me know.

No doubt there are other ways of doing it but this was done with what i has in my box.

Phil G8IOA


QRP labs Arduino Shield Kit Schematic #shield

KG5ZID Hardy
 

Is there a better schematic than the hand-drawn one shown in the assembly instructions? I am attempting to use this shield with an AD9850 DDS module, and the LPF kit. In particular, the AD9850_reset pin is not shown on the hand drawn schematic. Using the numbering scheme used on the schematic, this would be pin 15, next to Data pin 14 on the module header. On my shield, this pin appears to be grounded. Furthermore, the header pin which would normally connect to the Arduino Uno D12 pin also appears to be grounded. This is shown on the schematic to be connected to Band 4. I don't see any solder bridges but that's always a possibility!
--KG5ZID Hardy


Re: QRP-LABS Low Pass Filter upgrade

Timothy Fidler
 

It is possible to armour up say a 40 w PCB for a LP  filter  like the one from Far Ccts  (Also sold out of India  by Sunil Lakarami) with heavy Cu wire , solder stitched along  existinig traces.  you need to handle the bare wire with gloved hands so it does not get sweat on it so you can then spray it with Polyurethane varnish to protect the critical outer layer where RF will be travelling.  DO NOT flow solder all over the copper. you need bead welds of solder to the PCB trace every now and then. Obviously the CU is being run down the guts of the existing PCB trace.  Where you have vias in a PC B you will have to work out a solution.  Navships on Ebay sells TE insulated Cu wire 1.0 mm dia which can be a shovel out of hard place.  take care not to breath teflon fumes if soldering it.  Navships is also known as John's wire shop.  I don't believe he has any solid core wire greater than 1.0mm. TE insulated wire of any sort is a nice thing to have for this sort of duty. 

Sod's law - such a board will be sized for say type T50 toroids. If you want to move it to a HIGHER PLane you may get mechanical clashes. So a 5 filter PCB may turn into a 3 band PCB. " Ya get that on these big jobs"

regards, TE Fid


Replacement Parts for QCX+

Len W1LEN
 

I'm looking for a mail order/online source to buy small quantities of replacement parts for QCX+, specifically IC7 LM4562, and R25 3.3K ohm resistor.  Any suggestions would be much appreciated.  Thanks very much.

Len W1LEN

Virus-free. www.avg.com


Re: Thoughts on Low Power and fewer turns on LP filter toroids

Phil/K3UT
 

I’ve always kept a 50ohm dummy load on the output. I will take a look at L4 tomorrow, first by compressing and then spacing the windings.  Then i may remove a turn. More later. 

Phil K3UT 


Re: #40m qcx+ #40m

Bruce K1FFX
 

If your logging software is N1MM+, you may have better results using the "KENWOOD-SLOW" setting.

- Bruce K1FFX


Re: Select Button on Alignment QCX+ 20m

N3MNT
 

Could be a simple issue.  Make sure you did not install the know too far on the shaft ( close to the case) or it will not have sufficient travel to activate the switch.


Skeeter Hunt 2020 Results published.

Larry Makoski
 

To all Skeeters and Skeeter Hunters,

You are ALL chmapions in my book! Thank you all for participating - without you, this event is a big ZERO. You folks make it what it is. And while you're tops, special kudos go to:

Gene N5GW - 1st Place overall with 25,912 points
Kent as N0SS - 2nd Place overall with 21,316 points
Dave AB9CA - 3rd Place overall with 17. 806 points
Peter NN9K - 4th Place overall with 16,381 points
Marc W4MPS - 5th Place overall with 14.020 points

The 2020 Skeeter Scoreboard is available for viewing in its entirety at:

https://drive.google.com/file/d/18QkjuDoQik9OYXQeC19l4kUPCyAgYcQU/view?usp=sharing

The soapbox will follow ASAP as well as certificates to those who earned them.

Thanks again to all who particpated and and to those who sent in log summaries, comments and photos.

73 de Larry W2LJ - Skeeter Hunt Contest Manager - Skeeter # 13 in perpetuity.


Re: Thoughts on Low Power and fewer turns on LP filter toroids

Curt wb8yyy
 

Phil

the 5 watt outside is specified for higher voltage than 13.8 volts.  okay a few claim more, but I trust the designer's data. 

your rigs are working wonderfully 3 watts to 5 watts is a small fraction of one S-unit !  only your power meter knows the difference. 

okay to tweak a rig when building - otherwise we may as well order it already built (funny thing, that option is coming!). 

all seems well - enjoy its radiations - wow these QCX have wonderful receivers! 

73 Curt


Re: QCX #smoked ? #smoked

Curt wb8yyy
 

John

let's not conclude anything yet - but suffice it to say WSPR can be rough on this rig - the original QCX without any heat sinking on the bs170 finals.  I can't speak to the qcx+ on WSPR, but the heatsink at least looks nice! 

let's see - single band rig - if you do WSPR once each 10 minutes - I would think it should work if your antenna has a reasonable match.  kaput?  I would think only the bs170 finals take punishment - order a batch of them from W8DIZ if you are stateside. 

now i did smoke some bs170 in my QCX - when I plugged in GPS and did not realize it set rig into transmit.  hang in there I hope the QCX is still okay. 

73 curt


Re: DSB & AM on 222MHz with IQ receiver, can it be done? #building #vhf #si5351a #fst3253 #1.25M #fst3253 #ht #building #vhf #si5351a

Justin Kelly
 

Not exactly the direction I was looking to turn, but this seems to have some merit, https://www.rtl-sdr.com/rpitx-v2-released-easily-record-and-replay-with-rtl-sdr-and-a-raspberry-pi/

-Justin N2TOH 


Re: #40m qcx+ #40m

Don Blachura
 

Tu Ron. At 83 my mind is getting a little rusty.
Tu agn.

Don...w2xb


Re: #40m qcx+ #40m

Ronald Taylor
 

 Page 138 in the manual... Kenwood TS-480


4.28 CAT Control commands (PC remote operation)

The CAT command system is intended to allow the QCX+ to be used with logging software (general and contest) which uses CAT control commands to query the transceiver for information entered into the log, typically operating frequency, mode etc. A subset of the Kenwood TS-480 command set is implemented, with a few minor modifications.



page138image28583472

QCX+ assembly Rev 1.03                                                                                                           138


On Tue, Sep 8, 2020 at 1:30 PM Don Blachura via groups.io <haircutter=verizon.net@groups.io> wrote:
Need a liitle help. What rig do you select in logging software to use the "cat' on the qcx+?
I see the port in my Device manager, but from there I am lost.

Don...w2xb
(using aclog by n3jfp)


#40m qcx+ #40m

Don Blachura
 

Need a liitle help. What rig do you select in logging software to use the "cat' on the qcx+?
I see the port in my Device manager, but from there I am lost.

Don...w2xb
(using aclog by n3jfp)


Re: QCX #smoked ? #smoked

Shirley Dulcey KE1L
 

Most of the "12V" power supplies sold to hams are really 13.8V supplies out of the box. (Many of them can be adjusted with an internal trimmer.) A lot of ham gear is designed to operate best at that voltage, which is about what you get from a typical automobile while it is running. The power supply is probably working as designed.


On Tue, Sep 8, 2020 at 3:59 PM John Sharman via groups.io <jsharman6=sky.com@groups.io> wrote:
Finals are ok !


On 8 Sep 2020, at 20:45, ajparent1/KB1GMX <kb1gmx@...> wrote:

Define kaput,  and what item?

Likely fried the finals in the morning and during the day repeated tries finished the job.
THe PS I can only guess about.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: QCX #smoked ? #smoked

John Sharman
 

Finals are ok !


On 8 Sep 2020, at 20:45, ajparent1/KB1GMX <kb1gmx@...> wrote:

Define kaput,  and what item?

Likely fried the finals in the morning and during the day repeated tries finished the job.
THe PS I can only guess about.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


Re: Thoughts on Low Power and fewer turns on LP filter toroids

Hans Summers
 

Hi all

This problem has always come up at intervals on this group. 

It used to be that we could blame suspect capacitors for being lossy since several were found on occasion. 

Not any more! All capacitors are now NP0 ceramics manufactured by Vishay and procured from Digikey. All the toroids are from Diz @ kitsandparts.com. I don't think it at all likely that there are any quality issues with these US sourced parts. 

Which leads us just back to variations in component tolerances, winding styles, soldering (check grounded pins of capacitors which are harder to get soldered well to the groundplane!). And variations and errors in power measurement. All these variations are the most likely cause all along on most previous occasions too... but for sure the capacitors and toroids in the LPFs are really always good now. 

73 Hans G0UPL 

On Tue, Sep 8, 2020, 21:44 Michael.2E0IHW via groups.io <blumu=btinternet.com@groups.io> wrote:
Apart from soldering issues, this must be  the most confounding disincentive  for faint-hearted wonnabe QSX+ers ...

There must surely be a concise winding-checklist for genuine radio "amateurs" ?

Michael 2E0IHW
...........................................................

On 08/09/2020 17:57, Phil/K3UT (ex W3HZZ) wrote:
I've completed a 20M QCX+ and have just fixed a friend's 30M QCX+. Both are working nicely, but at 13.1 volts I get about 3watts output on both, using the onboard RF tool to measure (and less on my Elecraft wattmeter). 

To achieve that output, I had to take two turns off L1 and L3 and one turn off of L2 and fiddle around a little with the spacing of the windings. I did that with both radios.

Any thoughts why the number of turns differs so greatly from that specified in the build instructions? Both kits were shipped about the same time. Could it be a quality control issue of the toroids? I measured the toroids on the 20M version before I installed them, and they were spot on before I took the turns off. I didn't measure them after the turns had been removed.

I'm satisfied with the power output of the units.  Just curious why they aren't meeting the specs as stated in the manual?

Phil, K3UT


Re: QCX #smoked ? #smoked

ajparent1/kb1gmx
 

Define kaput,  and what item?

Likely fried the finals in the morning and during the day repeated tries finished the job.
THe PS I can only guess about.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting