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I have Sprite on 20M and using a trimmer on FL4 to allow peaking output.? Also using a 2N5109 for PA.? Rigged a battery to supply 13.8 V, the shack supply causes too much noise (any suggestions?).? Getting 400mW output, made contact with NE0F in Denver CO, about 850 miles from here as first contact with the radio.? There is a 'test' on this weekend so will wait until later to try working a few more stations.
72, Curt KB5JO
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Curt,
Good job on the 20m Sprite, trimmer for the series section and the
5109.
Can you determine the approximate frequency of the noise?? If so you
can notch it out. Otherwise a brute force (differential) pi filter might
help.
I found this info for filtering switching supplies and buck-boost voltage
sources:
These components act on noise components as follows.
Capacitors: Bypass noise currents to GND.
Inductors: Reflect noise currents.
Ferrite beads: Inductive component reflects low-frequency noise currents,
and resistive component converts higher-frequency noise currents into
heat.
Resistors: Convert noise currents into heat.
At 11:17 AM 5/30/2020, you wrote:
I have Sprite on 20M and using a
trimmer on FL4 to allow peaking output.? Also using a 2N5109 for
PA.? Rigged a battery to supply 13.8 V, the shack supply causes too
much noise (any suggestions?).? Getting 400mW output, made contact
with NE0F in Denver CO, about 850 miles from here as first contact with
the radio.? There is a 'test' on this weekend so will wait until
later to try working a few more stations.
72, Curt KB5JO
Chuck, W5USJ (ex K2OFN)
ARCI 5422, SKCC 19956
EM22cv, Rains Co., Texas
-- Chuck, W5USJ
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The PS noise is essentially 60 hz hum.? What is strange is the Pixie(s) are the only ones that exhibit this here.? The Rockmites all tolerate power from the shack supply quite well.? All of the other QRP radios in the shack use that same supply.? I am thinking it is because the Pixies have no voltage regulation into the mixer transistor, while the Rockmites have a 5.1V zener, resistor, bypass cap on the SA612 mixer supply.? And, the mixer itself has internal circuitry to reduce noise.
What is also strange is all of the Pixie variants including the Sprite put out only about 300-400 mW.? My? Rockmite 20 with a 2N5109 easily makes nearly a watt.? I am thinking the single PN2222 oscillator doesn't produce enough drive for more PA output.
I remain impressed that these simple radios can be successfully used to make contact, built many different versions of the "Pixie 2" and have made contacts with all of them.? The Sprite is the best of the bunch in my opinion.
Curt KB5JO
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Second QSO, this time 2xQRP with NA5N n NM, about 750 miles from me.? He was 559, he gave me a 329.
So far 19 QSOs with 9 states ( 7 on 40M, 2 on 20M ) using the Sprite.? Not bad for a $30 radio.
Curt KB5JO
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What a great catch Curt! Paul NA5N is a pretty famous QRPer and he plays with some awesome antennas! ;-)
I'm quite looking forward to my Sprite arriving.
73? Colin
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Colin,
Yes Paul is famous, this is only second time have worked him.
I wanted to mention that for my Sprite the trimmer is installed at xcl where the schematic calls for a fixed 22 pF cap, believe the intent was to vary the T/R offset with the trimmer,? I wanted both transmit and receive frequency to swing with trimmer position and used a fixed offset of 82 pF.
72, Curt KB5JO
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My Sea Sprite kit arrived at the weekend. I've just finished building the board, I've built the rig for 20m using a low pass filter. I've just done the smoke test and was pleased to observe that the rig fired up first time with no problems. I'm seeing 300mW from 12v and I also heard some CW from an adjacent frequency. Pleased to be an official Sea Sprite 20 club member! 73, Colin 
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Colin,
Beautiful! You do nice work!? Fast too!? I still need to print out the wrapper for mine several years after building it.? Wish we could QSO 2xSprite but likelyhood of that for awhile is zero.? Maybe when the spots come back about 2025.
I built mine with Chuck's 2.5MHz width BPF, and he has done some more detailed work with filter designs and testing.? I am getting about 400 mW with 12VDC and no problem with BCI.
Let us know how she drives.
72, Curt KB5JO
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Curt,
I have just test driven the Sea Sprite 20, it looks as though I have further work to do. I was getting very strong BCI. The station was identifying a "Radio Armenia International transmitting from Bucharest" Google hasn't helped me so far.
The problem I have is component supply, it just seems so hard to get hold of decent quality capacitors in amateur radio friendly values.
I have a NanoVNA waiting for a suitable project so I may experiment with a band pass filter. I have some 270pF caps, so that should get me to 540pF if doubled up. The filter I've seen asks for 510pF. I have one each of the toroidal cores (1x -2 mix, 1x -6 mix) so I'm just one core short. I do have the larger -6 cores though.
If all else fails, I'll see if I can get hold of the parts to put the 40m values in (my kit was short).
73, Colin
Colin,
Beautiful! You do nice work!? Fast too!? I still need to print out the wrapper for mine several years after building it.? Wish we could QSO 2xSprite but likelyhood of that for awhile is zero.? Maybe when the spots come back about 2025.
I built mine with Chuck's 2.5MHz width BPF, and he has done some more detailed work with filter designs and testing.? I am getting about 400 mW with 12VDC and no problem with BCI.
Let us know how she drives.
72, Curt KB5JO
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Colin,
I used 330pF and 180pF for the 510.? The 240 nH 8t on T30-6 and the
4.7uH I filled a T30-2 up with #26 then overlapped about 5 turns
more.
The 47u is a 10% but the filter came out quite close with the
VNA.
I would send you the parts I used if I can send them regular mail.?
I think they are thin enough to make a regular mail envelope.? Tape
them between two cards the size of QSLs.
At 04:42 PM 6/12/2020, Colin Evans M1BUU wrote:
toggle quoted message
Show quoted text
Curt,
I have just test driven the Sea Sprite 20, it looks as though I have
further work to do. I was getting very strong BCI. The station was
identifying a "Radio Armenia International transmitting from
Bucharest" Google hasn't helped me so far.
The problem I have is component supply, it just seems so hard to get hold
of decent quality capacitors in amateur radio friendly values.
I have a NanoVNA waiting for a suitable project so I may experiment with
a band pass filter. I have some 270pF caps, so that should get me to
540pF if doubled up. The filter I've seen asks for 510pF. I have one each
of the toroidal cores (1x -2 mix, 1x -6 mix) so I'm just one core short.
I do have the larger -6 cores though.
If all else fails, I'll see if I can get hold of the parts to put the 40m
values in (my kit was short).
73, Colin
On Fri, 12 Jun 2020, 00:45 Curt via
,
<rhulett1=
[email protected]> wrote:
- Colin,
- Beautiful! You do nice work!?? Fast too!?? I still need to
print out the wrapper for mine several years after building it.??
Wish we could QSO 2xSprite but likelyhood of that for awhile is
zero.?? Maybe when the spots come back about 2025.
- I built mine with Chuck's 2.5MHz width BPF, and he has done some more
detailed work with filter designs and testing.?? I am getting about
400 mW with 12VDC and no problem with BCI.
- Let us know how she drives.
- 72, Curt KB5JO
Chuck, W5USJ (ex K2OFN)
ARCI 5422, SKCC 19956
EM22cv, Rains Co., Texas
--
Chuck, W5USJ
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Chuck,
Didn't your recent work with the NanoVNA show best performance using? parallel inductances of 160 nH, parallel cap of 800 pF, series inductance 3.9 uH, series cap of 33 pF?
72, Curt KB5JO
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Curt,
I did this as an update to the user guide July 2017.? Pretty close
to the version with the VNA test fixture. The Elsie model is also dated
7/2017.
The 250 pF capacitors don't seem to be a standard value?? For the
VNA evaluation the caps were 330 and 180 pF
I've browsed through all my Sprite 20m filter designs and only find the
one here.
But, I finally found this revised Elsie model in an old list... seems to
be the one with the values you described.
And, it looks good: about 2 MHz across the flat part of the curve and
impedance right at 50 Ohms and high RL. No idea when or why it was
done?
At 06:58 AM 6/13/2020, you wrote:
Chuck,
Didn't your recent work with the NanoVNA show best performance
using? parallel inductances of 160 nH, parallel cap of 800 pF,
series inductance 3.9 uH, series cap of 33 pF?
72, Curt KB5JO
Chuck, W5USJ (ex K2OFN)
ARCI 5422, SKCC 19956
EM22cv, Rains Co., Texas
-- Chuck, W5USJ
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Colin,
I am sure 2x270pF (540pF) will work just fine.? Anything marked 510 isn't going to be 510 anyway.? You can use the toroids in the picture for the BPF, mine uses 9 turns on 37-6 cores.? You can use the 6 mix you have to make the series inductor, mine uses 29 turns on a 37-6 core.? You can squeeze or spread windings on the toroid cores to tune things since you have the VNA ( which I don't). I used a trim cap for the series cap and tuned for maximum output power.? Chuck can show you how to connect the fixture to do the testing.
GL n 72 Curt KB5JO
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Thanks for the offer of parts Chuck. I considered making a parallel capacitor but figured that the value of each individual capacitor would need to be fairly close?together in value. I do have 330 and 180p caps.
I've also acknowledge the later post describing a different filter.
I will order some small -6 toroids.
I have plenty of ideas to work with!
73, Colin
On Sat, 13 Jun 2020, 01:20 Chuck Carpenter, < w5usj@...> wrote:
Colin,
I used 330pF and 180pF for the 510.? The 240 nH 8t on T30-6 and the
4.7uH I filled a T30-2 up with #26 then overlapped about 5 turns
more.
The 47u is a 10% but the filter came out quite close with the
VNA.
I would send you the parts I used if I can send them regular mail.?
I think they are thin enough to make a regular mail envelope.? Tape
them between two cards the size of QSLs.
At 04:42 PM 6/12/2020, Colin Evans M1BUU wrote:
Curt,
I have just test driven the Sea Sprite 20, it looks as though I have
further work to do. I was getting very strong BCI. The station was
identifying a "Radio Armenia International transmitting from
Bucharest" Google hasn't helped me so far.
The problem I have is component supply, it just seems so hard to get hold
of decent quality capacitors in amateur radio friendly values.
I have a NanoVNA waiting for a suitable project so I may experiment with
a band pass filter. I have some 270pF caps, so that should get me to
540pF if doubled up. The filter I've seen asks for 510pF. I have one each
of the toroidal cores (1x -2 mix, 1x -6 mix) so I'm just one core short.
I do have the larger -6 cores though.
If all else fails, I'll see if I can get hold of the parts to put the 40m
values in (my kit was short).
73, Colin
On Fri, 12 Jun 2020, 00:45 Curt via
,
<rhulett1=
[email protected]> wrote:
- Colin,
- Beautiful! You do nice work!?? Fast too!?? I still need to
print out the wrapper for mine several years after building it.??
Wish we could QSO 2xSprite but likelyhood of that for awhile is
zero.?? Maybe when the spots come back about 2025.
- I built mine with Chuck's 2.5MHz width BPF, and he has done some more
detailed work with filter designs and testing.?? I am getting about
400 mW with 12VDC and no problem with BCI.
- Let us know how she drives.
- 72, Curt KB5JO
Chuck, W5USJ (ex K2OFN)
ARCI 5422, SKCC 19956
EM22cv, Rains Co., Texas
--
Chuck, W5USJ
|
Curt -?
All noted. I have some 220pF caps too, so could try 220+270 to give ~490pf.
I switched the Sprite on again this afternoon and there was no BCI, I guess Radio Romania International (yes, seems it was RRI not "Radio Armenia") wasn't transmitting!
Lots of chance for experiment.
73, Colin
Colin,
I am sure 2x270pF (540pF) will work just fine.? Anything marked 510 isn't going to be 510 anyway.? You can use the toroids in the picture for the BPF, mine uses 9 turns on 37-6 cores.? You can use the 6 mix you have to make the series inductor, mine uses 29 turns on a 37-6 core.? You can squeeze or spread windings on the toroid cores to tune things since you have the VNA ( which I don't). I used a trim cap for the series cap and tuned for maximum output power.? Chuck can show you how to connect the fixture to do the testing.
GL n 72 Curt KB5JO
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Curt - anymore adventures with the Sprite recently?
I have been building a QRP Labs 50 watts class C amp for 20m. I realised that I don't really use my QCX 30 so I'm swapping it over to 20m to drive the new amp. I'm also incorporating all the updates and mods, including new firmware. All this has meant that my limited time at the bench has been swallowed up and the Sea Sprite has been put on the back burner for now. I did get some more toroid cores and caps, so I should be able to try out a BPF pretty easily. (I pinched one of the yellow cores I used on the Sprite for the QCX, so it's currently looking a bit tatty!)
I will resume with the Sprite in due course, I also have a QRPme Corn Challenge board to play with.
Lots of projects on my list and it keeps getting longer!
73?
Colin
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Colin, ? I haven¡¯t used the Sprite in awhile.? Made a detour breadboarding a 1 transistor transceiver called a Pititico, invented by an op n Brazil. ? 
It works pretty well, especially since it is only 10 parts.? I eventually managed two QSOs with it, one to a station north of me about 160 miles and another NE of me about 200 miles.? It receives quite well, and RBN has heard me as far as 900 miles. ? Now I am in process of building a 5W10 transceiver from Kits n Parts.? It is an experimental conversion of the 5W20. ? I will be playing with the Sprite 20 also off and on while the plague continues to rage.? XYL n I are staying away from everyone including family.? My 50 year-old son, his girlfriend, and her little girl all caught the virus.? He is having a rough time with it, ten days in. He has no idea where he got it.? Probably at his job.? People who say it is a myth have no idea. ? GL n 72, Curt KB5JO ? Sent from for Windows 10 ?
toggle quoted message
Show quoted text
From: Colin Evans M1BUUSent: Thursday, July 2, 2020 3:23 PM To: [email protected]Subject: Re: [QRpmeKits] Sprite on 20M ? Curt - anymore adventures with the Sprite recently?
I have been building a QRP Labs 50 watts class C amp for 20m. I realised that I don't really use my QCX 30 so I'm swapping it over to 20m to drive the new amp. I'm also incorporating all the updates and mods, including new firmware. All this has meant that my limited time at the bench has been swallowed up and the Sea Sprite has been put on the back burner for now. I did get some more toroid cores and caps, so I should be able to try out a BPF pretty easily. (I pinched one of the yellow cores I used on the Sprite for the QCX, so it's currently looking a bit tatty!)
I will resume with the Sprite in due course, I also have a QRPme Corn Challenge board to play with.
Lots of projects on my list and it keeps getting longer!
73?
Colin
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Firstly, sorry to hear and your son and his family, sending best wishes. I deliver vegetables to between 50 and 70 households a week, it is a worry, but thankfully the virus appears to be in retreat over here. The bars and restaurants are allowed to open from this weekend but there's still lots of nervousness.
OK on the Sprite and the other projects- it's not just me getting side tracked on other projects then!
I have a Kits and Parts 1W40 and 1W30. I bought the 1W40 to build into a 'mock' paraset. The village I used to live in had a WW2 / 1940s weekend. Over the years I'd seen lots of old wireless sets fitted to the Jeeps but none of them worked, they were just for show. I'd always thought it would be cool to actually use a rig for real, having genuine CW contacts whilst the public watched. I don't own a period vehicle, let alone a Jeep, so I thought I could dress as a spy and carry a briefcase radio, setting up in a park tapping out CW on 40m from a shady corner! I added a Kits and Parts 5w amp, which I blew up because I'd chosen to omit the VSWR sense circuitry and didn't even think to make a wire link across. The instructions were later amended at my request to save other builder's bacon!? I couldn't find the transistors used in the Kits and Parts amp so I was forced to order from Diz. The postage cost was more than the transistor's worth so I decided to buy a 1W30 kit too. I built the 1W40 into a wooden 'briefcase' with amp, AF amp and loudspeaker, and home brew EFHW tuner. Unfortunately the rig has been disappointing, so it's on my list to disassemble and box up as stock, leaving as a barefoot 1W40. The 5W amp does work though, I'm sure I'll find a good use for it. I built the 1W30 and it's in a nicely finished case but I'm yet to try it on air.
The Pititico looks interesting! I built a G3XBM FETer for 80m, it seems to work but I've not actually tried it on air. The FETer uses a switch to change the circuitry around a single FET to make a transmitter and receiver.
73, Colin
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Colin,
They opened everything up here too, to their regret.? People started acting as if the virus was gone but it was just waiting to teach an unhappy lesson.? We have gone back to restrictions about two months ago.? Guess I need to read King's "The Stand".
I looked at the FETer but dropped it because it is really a transmitter and receiver using a switch to change modes.?
I have just the thing for the budding WW2 spy, a bayou jumper receiver ( early pre bayou jumper ) and a 2fer transmitter.? I had them paired before building the Bayou Jumoer from Four States.? Will send you the pair when plague eases enough for me to get to the post office.
Going to get the Sprite 20 out today for a drive.
Curt KB5JO
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