[W5SFA] QRP Labs U3S kit report

Mon Jun 26 20:15:55 CDT 2017

Gil,

Ray showed me how to measure the output power with an oscilloscope, it's not too difficult.   Toughest part was soldering in a small tab on the board for the probe to  tap into the RF.  Depending on the band, my U3S is putting out between 115 and 164 mW going into a 50 ohm dummy load.  But this is dependent on the bias setting on the transistor, so yours could be higher or lower.

I'll bet that adding the two additional transistors will boost the output close to 500 mW.

73,

Roger

From: w5sfa [mailto:w5sfa-bounces at w5sfa.org] On Behalf Of Gilbert Franke
Sent: Monday, June 26, 2017 7:49 PM
To: Mail List for the W5SFA Radio Club
Subject: Re: [W5SFA] QRP Labs U3S kit report

Roger, 

I think a little more power would be helpful.  I don't really know what I am putting out.  I'm listing it as 200 mW.  It is really amazing what it does!  .5 W might be nice.

I'm thinking about it.  I think antennas are what I need to concentrate on now.  

-- Gil

On Mon, Jun 26, 2017 at 6:41 PM, Roger Klein <rwklein at katyweb.net> wrote:

Gil,

I only built with one transistor to keep it simple, but I'm planning to add the other two.  Instructions say this will require more voltage to the transistors, so I'm going to try powering with 12v and use a 7805 voltage regulator chip to step down the voltage to 5V (so as not to fry the processor!).

I got a 10-pack of BS170 transistors, so if you or anyone else wants to try this I have plenty of extras.  Hopefully I will not release the magic blue smoke doing this - but someone has to be first :-)

Roger

From: w5sfa [mailto:w5sfa-bounces at w5sfa.org] On Behalf Of Gilbert Franke
Sent: Monday, June 26, 2017 4:42 PM
To: Mail List for the W5SFA Radio Club
Subject: Re: [W5SFA] QRP Labs U3S kit report

Thanks, Roger!  Did you build yours with three transistors right away, or just one to begin with?  I'll check out that antenna site.  Thanks.  Yes, that is what the manual seemed to indicate could  happen if only one string was received -- or both received, but not connected at the receiving end.

Dan, I know you will enjoy it when you get it done.

-- Gil

On Mon, Jun 26, 2017 at 3:03 PM, Roger Klein <rwklein at katyweb.net> wrote:

I thought I'd share my U3S experience, after taking it along on a recent trip down to Rockport.  I used a Par End Fedz 10-20-40 <https://www.lnrprecision.com/store/#!/EFT-10-20-40-Trail-Friendly/p/39885475>  lightweight antenna, and had it strung haphazardly up in some trees about 15' high.  I transmitted for 4 days on 20m and 40m without a hitch, and was being heard - maybe not as good as the better antennas back home but getting lots of reports.

When I started up at the new location, my grid square was automatically updated by the GPS to be in grid EL17.  The wsprnet.org map shows the location as the center of the grid square, which in this case was out in the Gulf of Mexico!  I then changed to sending two successive frames, so I could send my 6 character grid square.  As expected, I got a much more accurate map posting (EL17kx).  Not every spot showed the 6 character grid square though - only those stations that received both frames.  The stations that received only one of the frames only posted the 4 character grid square.

I think for a multiband antenna, the myantennas.com EFHW-8010 or EFHW-4010 could work well.  See http://myantennas.com/wp/product-category/antennas/efhw-multi-band/ 

You could also scratch build one of these types of antennas using a 9:1 balun.  But even with a poorly tuned antenna, I think we'd get some spots, and with the low power I doubt there would be any danger of blowing the transistor because of high SWR.

73,

Roger N5RWK

From: w5sfa [mailto:w5sfa-bounces at w5sfa.org] On Behalf Of Gilbert Franke
Sent: Monday, June 26, 2017 1:35 PM
To: SFAustin Radio Club
Subject: [W5SFA] QRP Labs U3S kit report

I'm having a good time with my QRP Labs Ultimate3S QRSS/WSPR Transmitter.  The GPS receiver works very well to give my location and frequency calibration.  I am heard on the WSPR network and posted on their map with almost every beacon, at 10 minute intervals.  I haven't seen any reports outside Canada and USA, but that is with a nominal 200 mW on 30M with an end fed halfwave antenna about 20 feet, north / south, and SWR of 1.3:1.  

You can see me on the WSPRnet.org map. Select 30M filter from lower left corner.  Because of the slow speed (it takes about 110 seconds to transmit my callsign, 4 character Maidenhead locator, and power!), sending the 6 character Maidenhead locator is not encouraged.  The four character locator put me between Halletsville and Shiner.  (If it had taken me all the way to Shiner, I would have been happy!)  When I re-configured for the full 6 character locator, I show up about 1 mile outside of Bellville!  As the manual says, this is a limitation in the WSPR protocol, not the U3S. Does anyone know what mode the APRS system runs? Do you think the U3S could handle that?

I have low  pass filters for 40, 30, and 20 M, but I don't have a well tuned antenna for 40 or 20.  I guess that is the next project!  

-- 

73, de Gil WB5RFQ

----

Gilbert A Franke <http://www.gilbertfranke.com> 
(361 442 6008 <tel:(361)%20442-6008>  - cell)
130 N Harris Street
Bellville TX  77418

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-- 

----

Gilbert A Franke <http://www.gilbertfranke.com> 
(361 442 6008 <tel:(361)%20442-6008>  - cell)
130 N Harris Street
Bellville TX  77418

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-- 

----

Gilbert A Franke <http://www.gilbertfranke.com> 
(361 442 6008 - cell)
130 N Harris Street
Bellville TX  77418

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