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QRPBuilder at FDIM
Gang, The QRPBuilder magnetically attached Iambic and Single lever Paddles are now back in stock. Also, this will be our fifth year at the Dayton FDIM vendor night on Thursday May 15, with all our products available. We hope to see you there. 73, Ken - WA4MNT Karen - KF4EEL qrpbuilder.com
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I bought a no name LC100a on aliexpress figuring it was worth the risk as they offered free returns. Unless I am really missing something, it looks like I will be taking them up on the free return. I understand my testing method is awful. 5% caps using one cheap device to compare to another cheap device should make most cringe but the Kaiweets meter is usually good. Those are 330pf caps. I have some 1% ones I should dig out but at this point I doubt it will matter. I did run and save all the self calibration routines several times. This is my fault for expecting anything better for $13 from a seller called Pure Pure Grocery Store but sometimes it is fun to roll the dice. Fun fact, the price is already up $5 from 2 weeks ago. Does anyone with one of these devices know of a trick I might be missing or as I suspect is this just more garbage made with floor sweepings?
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I've begun building this transmitter (Manhattan style) but cannot get the oscillator to oscillate. Has anyone built this before? I also put the oscillator into LTSpice and did not see oscillation. Does anyone know if this will work?
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L/C Meter Test
2
Steve R. sent me some mica caps rated at +-1% for use as pseudo-standard for capacitance checks. Thanks Steve. I'm sending him some transistors for his effort. Here is a comparison between his measurements using a DE-5000, which seems to be popular and mine arrives tomorrow, and a W8BH L/C meter made from a kit and a LC200A which I bought years ago on ebay when they were cheaper. I gave up my AADE to a charter school. The 5pF was marked +-0.5pF and not a 1% precision one. FYI MICA CAP DE-5000 W8BN L/C meter LC200A 5pF 5.2 4.381 4.51 62pF 62.7 62.20 62.59 160pF 161.2 158.8 159.8 592pF 589.2 578.2 588.5 1000pF 997.1 1028 1010 1300pF 1303.1 1289 1309 I can do a video doing the measurements when I get my DE-5000, but I'm too busy hanging wall paper now. :-) My $400 USD budget for rebuilding the lab is not at an end. Let's hope that I don't have to do a go fund me account to get more. :-) I get a brand new metal brake today for doing the K7QO enclosure procedure for projects. Life is good. ciao, -- chuck adams, aa7fo QRP WAS 17m started Apr 2, 2025 WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN PA,CA,CO,WI,NE,ID,IL,NC,NY,AL MA DXCC W,VE,JA,PY,ZL
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Building a PTO VFO
3
Daniel, A PTO VFO is a pretty simple beast, and the tuning coil arrangement is very easy and cheap to build. I use some small pieces of double sided PCB material, a brass screw and brass nuts, a piece of plastic drinking straw and some enameled wire. The vender Chuck mentions built his gadget based on what he saw in my instructions for the Tin Ear Receiver. Personally, the fact that the brass screw moved in and out a quarter inch or so from the front panel was never an issue. The first part of the attached article outlines how to build the tuning mechanism itself and the rest of a PTO VFO. Hope it comes through OK. Good luck with your build. 73, Wayne NB6M
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Source for 88 millihenry inductors?
5
Does anyone know of a source for 88 millihenry (88 mH) inductors? These were originally used by the phone company on telephone lines, and then later repurposed for use in the passive audio filters designed by Ed, W3NQN (now a silent key). 73, Douglas KA2UPW/5
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Active Mixer
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Hello, I remember some message on this group where someone said a DCR that was designed by Chuck Adams had an active mixer in it instead of a passive double balanced diode mixer as you would normally see. Was it a home brewed design with only transistors, capacitors, resistors, and inductors/transformers wound on toroids? Or something that included ICs or a commercial mixer? I am hoping a home brewed design. I am curious. I am trying to read up in various books on mixers and I remembered a message on QRPTech where somebody said Chuck's mixer was an active mixer. Thanks, Daniel KK4MRN
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Steve, AA7U, pointed the following circuit out to me and I just had to build one. Didn't take too long and it seems to work nicely. <https://techlib.com/newprojects.htm> Photo of my build attached. I have some calibration to do to make sure the I_C current is 10mA. You're going to need one of these if the 1,000x2N3904s I'm getting work out. I've checked out 1,000x2N4401s @ 294MHz and I'll give you pointers as soon as the final verdict is in. Less than $20 USD for each batch and the vendor has 50,000,000 in stock, so at $0.01 or so each that is quite an investment in inventory. The f_t above is subject to fine tuning on the fixture is just below the 300MHz min in the spec sheet. This is important as I finalize the ADC-40 transceiver BOM. I found BF245B's for $0.025 each and should have them by the end of the week. With help from DeepSeek, we have results better than what you would get with the 2N3819, MPF102 or J310 jfets. Film at 11. That's end of my budget limit I set, but I have enough for a lifetime. So, get the paypal account ready and I'll help you spend your money, if the measurements pan out. With 2,000+ transistors, I'll not be building anything with an IC in it unless it's in a kit. :-) Looking for others that have checked transistors thoroughly. Open to new and improved ideas. FYI -- chuck adams, aa7fo QRP WAS 17m started Apr 2, 2025 WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN PA,CA,CO,WI,NE,ID,IL,NC,NY,AL MA,OH DXCC W,VE,JA,PY,ZL
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Got the envelope with the selection of Honbay trimmers from Amazon. They arrived next day as advertised. They are cheap and I do mean cheap with respect to quality control and any value they may have using them. I won't be using them in anything I ever build. The tuning screwdriver is going to be almost 1/2 whatever you are using for the Murata N750 or N1200 caps. They are not on my list of approved critters in my lab. Got to Tayda and get them for around $0.18 to $0.32 for the few values they have in stock. So I took one for the team and wasted some money for the experiment. Hope this helps you. FYI IMHO, -- chuck adams, aa7fo QRP WAS 17m started Apr 2, 2025 WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN PA,CA,CO,WI,NE,ID,IL,NC DXCC W,VE,JA,PY
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You are invited to Pacificon
Pacificon 25 is going to be remembered as the return of qrp year. You can register and get your hotel room at Pacificon25.org for the 3 day conference that will be held the second weekend of October. I want QRP at Pacificon to be a success this year and I have decided to pass out at least 60 kits in each of the 6 qrp themed talks at Pacificon. We will be giving away absolutely free to the people who attend each lecture qrp kits. To get all 6 kits you will need to be at each lecture. And the kits are good ones. They will include the S1,S9 generator that was kitted by the NorCal Qrp Club. It has deactivated, but there were left over parts for the S1, S9. Darryl Swenson, K0AWB, donated most of the parts needed, and I supplied the rest. But the major portion of the parts was there. We have 60 of these kits. The next kit will be a simple voltage meter, that has a 2.1 x 5.5mm jack, a switch and a 3 digit display. Plug in a battery and read the voltage. Next are 2 boards to build the improved version of the Tuna Tin S transmitter that is the subject of Carol's talk, with the board done by John Sutter. You will get the main board and a 1 band module board. Kit #4 will be a continuity tester. Simple kit used to test to see if you have continuity between two points on a board. Kit #5 will be a dummy load that is built from 1206 resistors. It will give you lots of practice soldering 1206 surface mount resistors (board will be done by John but he doesn't know it yet). And kit number 6 will be a surprise. (I don't know what it is yet, so it will be a surprise to me too!! If you are on the fence about whether or not to come to Pacificon, maybe this will tip the balance in our favor. Yin Shih, N9YS is working hard to upgrade the original NorCal 40 to a modern radio with all kinds of upgrades. The kit will be available to anyone who attends Pacificon in person. Most of the parts will be premounted, and all that you will have to solder will be the frequency dependent parts and the connectors. It should take about 2 hours to build the rig. It will be available from me on Friday morning so you will have all day Friday and up til Saturday evening to finish building it. We will have an operating event on Saturday evening that will use the rig. Friday activities include passing out the Pacificon 40 kit, and our special no host banquet at Panera Bread, arranged by Dr. Megacycle, Jim Duffy of Albuquerque, who has 30 years experience of arranging banquets for us. We will meet in the lobby at 4:30 and leave at 4:45 for the restaurant which is about a mile away. Then we will come back to the hotel and our Friday night activities will start at 7:00 with our famous QRP Auction featuring auctioneer Doug Hendricks, KI6DS. There is a new feature this year in that we will be auctioning at least one of every Cal Qrp Kit that we have done in the last year. These kits are complete and just like the ones that we all had a chance to build during the year. No other items will be auctioned and the proceeds will go to the CalQrp Club. After the auction, we will have a show and tell of all of our home built projects. Everyone is encouraged to bring their projects for the event. This should be huge as we all have at least a dozen projects from the club. Bring your kits that you have built and modified for the rest of us to enjoy. And there will be time for those of you who haven't finished your Pacificon 40 to get expert help in aligning your rig. Saturday is the big day. We have 6 world class qrp speakers lined up to speak and the sessions are from 9 to 4 with an hour off for lunch. Then Saturday evening we will have our operating event using the Pacificon 40. Plus, we will have a building contest for any project that you have built in the past year since the last Pacificon. The top 3 will discuss and present their projects to the group, each getting 10 minutes. CalQrp has gone all out to make this a memorable qrp event. All we need is participants. Help us out and help yourself out by coming to Pacificon 25. You can register now by going to Pacificon.org. Hotel
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2025 Sasquatch Stomp Results posted
Hello All, The 2025 Sasquatch Stomp results have been posted to the Sasquatch Stomp page on the pnwqrp.org website. If you google pnwqrp.org it will come up right away. We had good band conditions this time, especially on the higher bands. Participation was up, too due to the better conditions. A big thank you to all who got on for the event. 73, Wayne NB6M
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Hey, I was thinking of getting some parts from Tayda Electronics. I think they have a warehouse also in the US but not sure if all the parts I need are there. I think some of you have gotten those D882 transistors before and had good luck with them? https://www.taydaelectronics.com/2sd882-transistor-npn-30v-3a-to-126-2sd882l-p-t60-k.html US $ 0.14 each. And get some heat sinks for the D882 transistors above but also those 2SC5706 I got from kits and parts. But not sure about the packaging of either of those. So, not sure what heat sinks where work for either of them. Some trimmer capacitors too. I think Steve buys his from there and they work for him. Question - good place to get NG0 / CG0 good quality capacitors for VFO and filters right now? Sure, I got a value boxes of capacitors off Amazon and I checked them and they seem to be in range of their stated tolerance. But when it comes to a VFO and filters, I think better quality capacitors are needed. 73 Daniel KK4MRN
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Mike that page just shows you what the values that were originally made. If you go to Mike's order page you will see that all he has is the 560pf which I THINK was part number 23PS156. The "S" indicates axial. A "W" indicates radial. If you search Mouser "Film Capacitors" you will not see Xicon listed but they were at least the last to make them and Mouser does have ONE type in stock. If you specifically search for 23PW210 which is a 1000pf radial mount (I hate the axial mount but that was all I used to be able to find). Anyway you will see that they have 87 in stock. That link is: https://www.mouser.com/ProductDetail/Xicon/23PW210?qs=LLoUvApQnRQP4Qc1L2vSdw%3D%3D 1000pf 87 in stock I recently placed an order with Mouser for some value and after a month was told that they could find 4 (repeat FOUR) they could ship (at $10 shipping for four capacitors weighing less than an ounce!) and that the manufacturer (Xicon) had obsoleted their polystyrene capacitors and would not be making any more so my other 96 pieces got cancellled. One ebay seller I recently bought some from was LF Components Inc. He lists only 3 values available and one is the 23PW210 radial mount: https://www.ebay.com/itm/400865262914 and his other 2 listings are: 2200pf: https://www.ebay.com/itm/166533082544 and 23PS110: https://www.ebay.com/itm/401134034384 Not sure why the 100pf is more than double the price of the others. These are all lots of 100. I had asked him if he had the value that Mouser back ordered and then could not supply for me and he said he did not have any and could not get any. That should tell you that they are disappearing. I am not sure if that helps or not or if the information was useful for others. Good luck. Jim Pruitt WA7DUY On 4/13/2025 11:12 AM, Mike N2MS via groups.io wrote:
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Precision valued parts
4
I have, in the lab, freq standard voltage standard resistor standard all within 0.1% or better. NIST traceable. All I'm lacking is capacitor and inductor standards. I found the following on ebay and just for its looks alone I'm willing to eat up 10% of my remaining budget for parts to get one. You have to appreciate the design. IMHO. <https://www.ebay.com/itm/230687690580> 16.5nF 1% Needed for multiple L/C meter checking. I used to have some 104.0pF 1% caps, but can't find them. Inductors may be more of a problem. Ideas? Anyone else obsessed? -- chuck adams, aa7fo QRP WAS 17m started Apr 2, 2025 WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN PA,CA,CO,WI,NE,ID,IL,NC,NY,AL DXCC W,VE,JA,PY,ZL
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Yan: Re: [qrptech] Oak Hills Research
Dear William Thanks for the comment. To be honest i did not realize or check there were ohr sub directory before upload. ?t was late night and I tried to help and share with ham spirit. I will check and remove if there were any duplicates. Sorry for inconveience 73s Hakan TA0G Yahoo Mail: Aray?n, Organize Edin, Y?netin 4:50¡¯¡¯17e¡¯ 17 Nis 2025 Per tarihinde, k6whp <k6whp@...> ?unu yazd?: Hakan, Very respectfully, there are already copies of the four OHR manuals you uploaded. They are in the "OHR" sub-directory. You might want to inspect and -- if duplicates -- remove yours as space is somewhat limited. If they are NOT duplicates, then move the unique manual(s) into the sub-directory so as to keep them in one place and easier to locate. Again, meant politely. Thank you for your contribution. -- William, k6whp -------------------- "Cheer up, things could get worse. So I cheered up and things got worse."
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Oak Hills Research
10
Is there a specific groups.io site for Oak Hills Research transceivers? A friend of mine has an OHR Spirit transceiver, and he is trying to find information about it, manual, and schematic. Thank you. Dave K8WPE
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OHR 100A Manual
5
Hello all, I owned years ago the OHR 500 (stupidly sold it) but today I got a OHR 100A in mint condition but without any documentation. Is there a digital version of the manual available? I did not find it in the Files section. vy72 Kees PA1CJT
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I took a shot at some 330pf mica caps on eBay. https://www.ebay.com/itm/167142446024 They showed up in the mail today well within the promised time frame well packed in a small cardboard box. According to my cheap amazon meter and ridiculously long leads, I'm happy. I am reluctant to recommend anything that I haven't actually used yet but I would buy from this seller again. It is worth noting the seller was responsive to an offer a few bucks below the buy it now price. -- ¡ì97.313 Transmitter power standards. (a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications.
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This time I am sharing my latest project on Github: https://github.com/3ym3ym/af_chain4dc_rx If you, like me, don't like the low gain and hiss of LM386 as the AF amplifier of your receiver project, try this design. It has extra gain, matching the lower level of simple DC receivers, a nice active LPF based on the idea from Ashhar VU2ESE, and a TDA2822 PA. All parts can be from Aliexpress and the PCB can be ordered from JLCPCB, for a total BOM of a (very) few dollars per board if you build 5 and chose the cheap shipping option (I know, I know, not for long...). Assuming you already have resistors and capacitors. Well, maybe the MMBT3904 input transistor should be a genuine one for guaranteed low noise, but even that is not critical. It can also be built using TH parts and your favorite construction technique. One thing that is missing is AGC. I tried a few simple options to keep the complexity and the cost low, but didn't like any of them. 73, Mike AF7KR
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I don¡¯t know why I¡¯ve not thought of it before. A Diamond blade from a wet saw, installed in a wood saw, goes through FR4 like a knife through butter.
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Image Name
Sat 8:39am
Sat 8:39am