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Author Topic: Simple QRP Transceiver in Major DX Contest  (Read 4535 times)
K0OD
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Posts: 2557




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« on: February 19, 2013, 07:06:16 AM »

Spent last weekend in the ARRL CW DX Contest using an Oak Hills 40-meter QRP kit transceiver powered by lantern batteries  I’ve done lots of contesting in my 50+ years in the hobby, usually with simple stations, but this was the technological low: $150 QRP kit radio, a vertical and a Midwest QTH.  What pain!  What fun!
 
Making Qs with 5 watts was among the least of the challenges. And the simple receiver pulled in distant DX easily.  While the OHR-100A is spec’d at 400 Hz minimum bandwidth, stations of just moderate strength 2 kHz away could be heard in the passband. No razor sharp skits for me! I could generally deal with the QRM but lining up the varactor-controlled radio on a DX station was the huge problem. With state-of-the-art contest receivers, if callers are even 200 Hz off frequency they may not be heard. Plenty of DX stations didn’t hear me.

Mother Nature cooperated. 40 was wide open and quiet. Still it was a tough slog. By Sunday evening I had 73 DX contacts with 45 countries including a few goodies: 3V8BB, 6V7S and 3D2RX.

Anyone else like to DX contest with the simplest of equipment?    
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W1JKA
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« Reply #1 on: February 19, 2013, 08:42:36 AM »

   Yes, me. Point giver only in contest as I am not interested in wallpaper,just fun.DX signal separation on my MFJ cubs easily solved with my cheap HI PER MITE 200hz outboard filters.
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NU4B
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« Reply #2 on: February 19, 2013, 08:53:51 AM »

Those were some nice results with the OHR 100A. You got about half of DXCC on 40 in 1 weekend! Congrats on the great 40 meter work! That 3V QSO was really nice!

I ran unassisted with a HW-9 last weekend. On all bands (80-10) I made 198 QSO's  and 61 countries. The power was 4 watts except for 10 where the power was 3 watts. I didn't use batteries and my antennas were a windom and a HF5B. The "narrow" filter on the HW-9 is 500 Hz.

I didn't work anything really rare (although making any DX contacts running QRP is always exciting to me) but I did work 3D2RX on Rotuma on 10 meters, KH6 on 80 meters is always nice, and VQ5RP who was running 5 watts from the Turks and Caicos Islands - that was my 40th country for a 2 way QRP QSO.

The ARRL DX CW contest is a really fun contest. As I always say - what could be better than hundreds of DX stations on the air at the same time, all with their antennas pointed toward North America?
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KU4UV
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« Reply #3 on: February 19, 2013, 04:26:02 PM »

I have been wanting to build one of the OHR kits, maybe for 20 meters and use it on Field Day this year.  They look like really nice kits.

73,
KU4UV
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KF4LXB
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Posts: 36




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« Reply #4 on: February 19, 2013, 05:50:08 PM »

I used my Weber Tri-bander from Hendricks during the contest. It did well and I got a few countries but I'm still very slow with CW so jumping in full bore wasn't going to happen. It was fun though and all QRP DX contacts are exciting to me.
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Christian
Albemarle, NC
EM95
http://kf4lxb.blogspot.com
K0OD
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Posts: 2557




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« Reply #5 on: February 19, 2013, 06:44:48 PM »

Tunisia was easy. He was CQing around 7070 with few takers around my midnight. I spent a lot of time high in the band where the QRM and competition was less. 

The Hi Per Mite is rated at 200 Hz but at 3 dB down, not the usual 6 dB. I don't believe the 400 Hz spec on the OHR. My guess is that's based on 3 dB also. Lord knows how these work at 60 dB down which is the appropriate measurement point for contesting.

It's actually a problem in a contest that the OHR receiver is so hot. Yesterday I did some A/B testing between it and my $2800 Flex-5000. The weakest signals on the Flex were just as copyable on the OHR  (that shouldn't surprise most experienced hams). On 40 the limitation is band noise not receiver sensitivity.

---
After thinking about the Hi Per Mite, I just dusted off my old unused Timewave DSP 9 audio filter. My Flex wouldn't benefit from it. But the Timewave makes a world of difference with the OHR.  However, as the radio gets more selective its varactor tuning limitations magnify. I'm using the stock OHR pot. They offer a 10-turn "high precision" pot but that covers up the front panel markings so that the optional digital dial is recommended. Each solved problem presents new ones!

The DSP 9 costs more and may weigh more than the OHR-100 and it uses an amp of current! I'm thinking of building in the Hi Per Mite which would improve selectivity while retaining the radio's simplicity.

The OHR-100a is a nice kit. I bought it mainly to give my son, an electrical engineering student, some soldering experience.


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NI0C
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« Reply #6 on: February 20, 2013, 11:32:15 AM »

Hi Jeff,
Your posting reminded me of a similar experience a few years back, using my Elecraft KX1:
http://www.mail-archive.com/elecraft@mailman.qth.net/msg16585.html

Cheers & 73,
Chuck  NI0C
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K0OD
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Posts: 2557




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« Reply #7 on: February 20, 2013, 05:49:12 PM »

Hi Chuck:

In 1992 I cracked the top 10 nationally QRP in the ARRL CW DX contest using an Argonaut 509. Big thrill was working a JA on 80. Ten meters was red hot that weekend as I recall and I spent a huge amount of time on that band.

I vaguely remember making a handful of DX Qs in some contests using a Ramsey QRP transmitter kit at about two watts. With its VXO I could only move a few Hz +- its crystal frequency.

Last year I turned the power down on the OHR and entered one of those QRPP contests. Result: ZERO contacts in about an hour!  I've got the OHR working a lot better now so I may try to beat that.

Fun trying different things. Nice too not worrying about TVI complaints.   
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NU4B
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Posts: 2240




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« Reply #8 on: February 21, 2013, 02:47:44 AM »

Hi Chuck:

In 1992 I cracked the top 10 nationally QRP in the ARRL CW DX contest using an Argonaut 509. Big thrill was working a JA on 80. Ten meters was red hot that weekend as I recall and I spent a huge amount of time on that band.

I vaguely remember making a handful of DX Qs in some contests using a Ramsey QRP transmitter kit at about two watts. With its VXO I could only move a few Hz +- its crystal frequency.

Last year I turned the power down on the OHR and entered one of those QRPP contests. Result: ZERO contacts in about an hour!  I've got the OHR working a lot better now so I may try to beat that.

Fun trying different things. Nice too not worrying about TVI complaints.   

Hey Jeff,
 Back 2003 I ran a 20 meter Rock-Mite in the IARU contest hooked up to a HF5B. I got enough xtals to cover the 20 meter CW band. I installed a 8 position switch and a primitive VXO. I also included a Freq Mite and audio filter. I made 11 contacts (with 11 countries) mostly with EU but my best contact was with P3A in Cyprus. It was much fun running 500 mW. My Rock-Mite is in pieces waiting for me to put it back together in a nice box, but lately I've running my Sierra a around 700 mW and DX'ing with it. Condx were much better back in 03.  Grin
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