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Oak Hills Research
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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
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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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looking for parts
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Gang, Does anyone have a good source of polystyrene capacitors to point me to? I need a 330pF cap for my current project, plus some spares :) Thanks... Alan, N8WQ
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BPF for DC receiver video
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For Dave, AA7EE, and anyone else interested. I added about 3 mins at the end of this video showing that a toroid inductor in free space, vertically mounted on a PCB or horizontally mounted on a PCB has the same value. Now the nits are going for the 3rd and 4th digit, but fluctuations occur in the process of moving the toroid around and the spacing of the leads, thus the stray capacitance across the toroid causes a very minor change in the total. I will come back, after I finish this and ADC-40 (I'm doing the transmitter on the side), and do a complete video on toroids and why they are your friend. Once you get over the fear of winding the critters, you will use them everywhere. Well, almost..... <https://youtu.be/hAM1GkzwXB8> is the video by AA7FO for your entertainment. Watch the whole thingy and add a like to help an old man down on his luck. :-) And trying to get to a polished presentation sometime in the future. 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,LA DXCC W,VE,JA,PY,ZL
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Anyone built Charlie Morris ZL2CTM Simple SSB Transceiver?
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Hello, Has anyone built the Simple SSB Transceiver that was shown on the blog and videos by Charlie Morris, ZL2CTM? Any suggestions? https://zl2ctm.blogspot.com/2021/01/simple-ssb-transceiver.htmlExp While I was trying to figure out what parts to get for various projects I wanted to work on, I realized that he was targeting a portion of 80m from 3.5 MHz - 3.6 MHz for the Band Pass Filter. But in the USA, I cannot do 3.5 MHz - 3.6MHz because no voice mode is allowed on that portion in my region. So, I need to move this up. And really, since this will be QRP, I do not expect to be getting any DX. And since I would share this with others, most hams would have a General. And I probably be more interested in targeting 3.8 - 4.0 MHz since this is where I hear most things anyways. So, this is where I need to learn how to do some of the same math he shows in his videos and his blogs to come up with his Band pass filter and IF Amp, etc. So, my center frequency for a band pass filter would be 3.9MHz. I looked on kitsandparts for their low pass filter board only and looked at it. And its links and led me to LTspice which is free so I downloaded it. So, I will try to reproduce what Charlie did first. Then proceed with my own stuff. I wanted to get toroids from kitsandparts. But now I am not so sure. Because now I will need to re-think the project for my region. If I go with the NE5334 preamp and LM380 amp ICs, they both can be found at Mouser in stock. Anyways, I like the video how he went about designing it. I like the use of the double-balanced diode mixers. Except, I want to do Manhattan construction on island pads instead of strip board. Anyhow, I maybe over my head and need to learn the electronics math and theory here. But I thought I would see if others have tried first. I am willing to do my home work. There are some radios I have built to compare to in the past like Curt's transceiver and Norcal 40A / 40B. So, there might be things there I could learn from including its book EOR. Charlie did mention he used the book Solid State Design for the Radio Amateur as a guide. Anyways, when I was at Adafruit, I noticed they were low on their Si5351A breakout boards. So, I ordered some. I liked how Charlie Morris showed the math how he determined values he got. So, that is a good starting point for me. I just got to figure out where he got that from. I even looked at the band pass/low pass filters at QRP Labs, but they take about a month to come from Turkey - and that is during good times. Not sure how things would be now. I do have a low pass/band pass filter from them for 40m but not 80m. But the filter is centered for CW - not SSB voice portions of the band. Thanks, Daniel KK4MRN
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Delay in shipments
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Alan, I feel for you bro. I ordered some valuable parts that I needed for projects from China before the tariffs kicked in. Envelopes worth $5.99, $6.34, $10.25, ... have been sitting at the airport and harbor in L.A.,CA for a week now and I am guessing that I will never see them. The backlog has got to be several warehouses full by now. The manpower alone has got be costing a lot more than the revenue for the small stuff. On 4/13/25 07:26, Alan N8WQ via groups.io wrote: > Gang, > Is anyone else having a delay in getting a shipment from Jameco? > I ordered parts on 3/25/25 and still have not received shipment. > Just curious... > > 73, > Alan, N8WQ > > On 4/11/25 17:04, k6whp via groups.io wrote: >> In keeping up with the mob, I had been buying my trimmers from >> JameCo. They are the ceramic ones and -- importantly -- a slot >> screwdriver fits and can turn the little buggers. (Done with the >> little brown plastic turdballs!) >> At increments of 10, they are 99 cents and at 100 are 89 cents. >> Be warned and be ready to order $20 of stuff otherwise they tap you >> for the difference. >> -- >> William, k6whp >> -------------------- >> "Cheer up, things could get worse. So I cheered up and things got >> worse." >> > > > > > -- 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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Help aligning VFO
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I am building an Ozark Patrol regen. The stock tuning range is very large and I would like to limit it. By default, there is a SPDT switch that adds a parallel capacitance for a second range. My goal is to align the two ranges with the 20 and 40 m bands. Math shows that I need two fixed capacitors (one in series with the tuning, one in parallel with that) for each band. My thought is to replace the SPDT with a DPDT. I would build the circuit for 20 m and the switch poles would select in the appropriate differences to each fixed capacitor. Does this seem reasonable? Is this how it's done?
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Oak Hills Research (SP-1 manual)
I downloaded the SP-1, 20M manual just now. Thanks, Chuck! https://archive.org/search?query=ohr+spirit+1 Steve AA7U
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20 pf ceramic trimmer caps 40? each (qty 50) delivered from AliExpress
https://www.aliexpress.us/item/2251832645851677.html?ug_edm_item_id=2251832645851677&pdp_npi=4%40dis%21USD%21%2417.00%21%2417.00%21%21%21%21%21%402151e05a17444595335345189d181e%2165026062923%21edm%21%21%21&edm_click_module=item_detail&edm_log_data=edm-item-list-one-column.store-product-log-link&tracelog=rowan&rowan_id1=aeug_edm_84139_1_en_US_2025-04-12&rowan_msg_id=3212biz_search_product%3A0%3A0_577655577%24d173c597c1fe471fbc2d817627cca52e&ck=in_edm_other&mem_info=Kh9KBwMNoU8nqYqW8afaqA%3D%3D-100103-aeug_edm_84139-NeUIED0Kpdu1EGthwcNhm%20OAyttfpOfUucGiWZhD0C8%3D&gatewayAdapt=glo2usa
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Reprieve from tariff possible?
It appears that most of the chips, transistors, electronic parts are now exempt from the tariff. Mostly I believe codes 8541 and 8542 affect us. https://content.govdelivery.com/accounts/USDHSCBP/bulletins/3db9e55 Updated april 11th. ?
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When PCB's are too expensive, and you're out of copper boards.
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https://www.hanssummers.com/101/1011.html -- Ryan Flowers - W7RLF https://MiscDotGeek.com W7RLF Prototyping Boards MiscDotGeek YouTube Channel
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A few weeks ago, I started building a 2N2/20 from a kit and ran into a problem with what appears to be a lack of gain somewhere in the receiver. I couldn't figure out where the problem lay. As a result, I thought that if I scratch-built a 2N2/20 using the same schematic as the Norcal kit version, I'd have a working unit with which to make measurements and comparisons. I've been wanting to scratch-build a 2N2 rig for years now anyway, so this was a good opportunity. I wasn't going to post anything until it was completely finished and fully operational, but I'm running into a small snag, so thought I'd share my progress so far and share the info, in case anyone can shed some light. The picture shows the state of the build as of 2 days ago. Everything seems to be working normally, based on simple tests touching wire antennas to the inputs of the various stages, and listening to the sounds from the speaker. The only abnormality is a slight instability in the IF amp stage immediately following the main 4-pole crystal filter. I have circled this stage in the second picture and also in the schematic. It manifests itself as a scratchy noise in the speaker. When I bring a finger in close proximity to the toroidal transformer T11, or either the 100 ohm resistor R36 or 01.?F coupling capacitor C46 that feed the input of the MPSH10 transistor, the noise stops, but the gain of the receiver strip is not affected. It just kills what sounds like some kind of parasitic oscillation. I replaced the 0.1?F cap C46, suspecting a noisy component, but that wasn't it. I may end up rebuilding the stage. We'll see. Anyway, the debugging process is engaging, and it gives me something to do when I get up in the morning. In other news, I've had the pleasure of two very brief QSO's with Chuck on 17M in the last few days. QSB was working against us, but I'm happy with brief exchanges anyway. Chuck and I are only about 600 miles apart, so it's not too challenging a haul for a couple of QRP'ers. Dave AA7EE Dave AA7EE
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Did get two chances to work Dave, AA7EE, on 17m. He called me once and I called him once. Time of day when you are 599 and 15secs later you are gone. Nil. Nada. Zilch. Thanks Dave. Attached is the audio amp board about ready to go. Not as neat as Daves work, but it is sure fun to build. I had to start this project his morning and I'll have it done by sunset. Using the same size board, but sheared into 3 parts, I'll build the other three sections. Then the plan is to attach them to the back of this board, thus coming up with what may be the smallest form factor or all. I'm not in the same league as Dave, AA7EE, and Jim, K8IQY, but I do enjoy working the technique. I recommend it for anyone who has a small project to learn with. Just do it. The Manhattan Madness continues. 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 DXCC W,VE,JA,PY
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Help aligning VFO (Ozark Patrol regen)
9
Hi Ross, On mine, the Low band tunes 3.90-5.24 MHz; High band tunes 5.46-- ~19 MHz, as you note at least the High band is very wide tuning. Your scheme would probably work but I predict it will take a lot of experimentation to achieve it. Good luck and please let us know how it all turns out. 73, Steve AA7U
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The end of inexpensive printed circuit boards and parts
20
As some of you may be aware, the president has eliminated the de-minimis tariff exemption for China and Hong Kong. Under the executive order, packages coming through the international postal network will either be subject to a fee of 30 percent of the value of the goods, or $25, rising to $50 in June. Whichever is greater. This means the duty will be $25.00 for packages from these countries from May 2, 2025 and $50.00 from June 2, 2025 Onwards. Relevant news article: https://www.nytimes.com/2025/04/03/business/trump-de-minimis-china-shipments.html This means no more inexpensive printed circuit boards from Chinese manufacturers such as JLCPCB and PCBWAY and no more inexpensive parts from LCSC or Aliexpress. The only way we'll get inexpensive circuit board fabrication in the future is if some US-based circuit board manufacturer decides that the hobby market is big enough to service. Of course JLCPCB et. al could open a plant in another country, but that would be a risky proposition. The de-minimis tariff exemption could be eliminated from other countries in the future. So if you have any PCB designs ready or parts needs to submit it would be prudent to submit them soon to take advantage of the low costs before the de-minimis tariff ends. You also should make sure that your design ships out before the middle of April so that it doesn't get held in customs for duty payment. If this de-minimis exemption isn't relaxed by the president, then guess I'm going to have to find something else to occupy my time for the near term as these increases are going to make homebrewing using fabricated PCB's too expensive. Steve WA6ZFT
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For those of you wanting to do Manhattan construction. You want to plan ahead as much as possible. And not spend a lot of time being an artist. I found that if I use a membership card for a gated community that has the lanyard hole already in it, it works to easily place and draw pads on paper with a pen or pencil. Possibly use an expired credit card and use the hole punch and make the hole sizes you need. Punch through the magnetic strip and card numbers for security. And I just draw a from pad to pad with a centered space with the part number, i.e. R1, and I don't have to spend a lot of time drawing outlines for resistors, caps, etc. Does not have to be to scale and you adjust as you build. dit dit -- 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 DXCC W,VE,JA,PY
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Encyclopedia of Electronics Vols 1-6
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Gang, Probably, most of you know about the Graf series of books titled "Encyclopedia of Electronics" with volumes 1 through 6. Just about anything you are looking for may be in there. Crystal oscillators to sirens. Amplifiers of all types and the list goes on. All six volumes are on archive.org and are downloadable. If you are looking for something to do, then you should consider spending the next three or four months reading these in your spare time. You wont have any spare time when you start. Been there. Done that. Or read them in place on the web. FYI chuck, aa7fo
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