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Re: Is there an easy way to test sa612 smd chips
开云体育I found three different types of DIP 602s in my stash.? Signetics SA602N, 1989 date code, 22.3 kohms; Philips SA602AN, can't decipher date, 11.2 kohms; NXP NE602AN, can't decipher date, 11.5 kohms. I suspect manufacturers have their own somewhat different fab of these chips which accounts for the differences, and has nothing to do with specific package type. Steve AA7U On 5/23/2025 8:54 AM, Dave AA7EE via
groups.io wrote:
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Re: QRP power measurement and AA7FO lab and web report[long]
Hey you were the guy advocating that a vxo offers enough tuning span (-:
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The pll does add complexity needing microcontroller and display. Enough to warrant getting a qcx mini instead.?
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I recall kitsandparts having si5351 hardware and code.?
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Vxo are more nice when the xtal combo pushes it up in frequency. Like the 38S design that can cover much of the 30m cw span.?
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Crystal Searching
Gang,
For those that haven't stocked up over the years on crystal deals or renewing their stock like I am, here is a list for you to go through at your time of choice.? If you are interested, I'd recommend you do so rapidly as the climate is a changing.? See the 4.032 and 10.000 vendor and what I got before things changed. Presented here to save you time that I spent on searching the web and I just got the tip of the iceberg.? Share if you have better deals. ------------------------ <> ?? o? about $0.64 per critter for 10 with free S&H ?? o? I've ordered here and was happy and you get ????? them quick. <> ?? o? I got my 4.032 and 10.000MHz here when it was ????? free shipping!? But, the $50 S&H is ridiculous ????? now.? He did it after the trade wars started. List of vendors I've ordered from and some are on the boat as we speak.? I'll come back with reports when I receive them, but I show them here as a current status in case the vendor later decides to change things for the worse.?? This list is for the small gamblers among us.? I went out on the limb on this one.? I'm not responsible for being the village idiot. <> 14.318MHz <> 15 freq options <> 10 freq options <> a bunch! <> options And while I'm wasting your time, take a look at how much quartz is being manufactured.? Quartz crystals are used in more places than you think about.? Enjoy.? I know that I do for this one. Things start at 3:00 or so on the factory floor. <> -- 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,WV MA,OH,OR,RI,MT,WY,WA,MI DXCC W,VE,JA,PY,ZL,TX9 |
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QRP power measurement and AA7FO lab and web report[long]
QRP Power:
See <> manual for how it is done with a dummy load.? Unfortunately QRPGuys are shut down for a month due to traveling on vacation. The power formula on the PCB is very very easy to derive and easy to compute on your phone calculator.? $20 is pretty cheap for thing IMHO.? I'd like them to change the pin out to allow a two pin Arduino cable to be used with the center pin on the board going to ground. Makes it easier for me, and I like easy. AA7FO Web Page: Because of the security notice threat that was coming up on my old web page, I have moved it. <> Note that I have revived some of my legacy writings on Manhattan construction, 1W and 5W building guides for those of you still hoarding the unbuilt kits in secret storage locations.? The money I save I'll donate to qsl.net to keep them going.? Not a friend of money for nothing and chicks for free, as the song goes.? I'm trying to get time to get back to writing, but its more fun to build and operate. I'll let you know how my combo of 10.000MHz(VXO) and 4.032MHz(IF) work out.? I'll measure the MDS with the old S1-S9 generator from NorCal and report back first thing.? You still have yours?? Battery check. AA7FO YouTube Status: Lost use of my video camera after 20 years of faithful service, so if you are a vlogger, let me know offline (I'm sure this group isn't interested in how to do it) what a good deal is.?? Too many options on amazon.com. Want one with macro capability for the closeups of boards etc. Manhattan Build: Awaiting QRPMe pads to get the SST build going. FYI.? If you look at the crystals needed, some are very hard to find.? But, look at the 1W frequencies in the retired kits on kitsandparts.com for easy frequency combos to find on ebay and aliexpress for less than a quarter a piece in quantities of 10 with free shipping.? Search the isles for what you need.? 40m is the tough combo. Experimental Venture: Someone in this group can open source a technique for using the cheap Si5351 module to replace the VXO and allow us to use any on hand crystals for the IF we want with the usual caveats on birdies.? May already be available from unknown source previously written up. FYI 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,ID,IL,NC,NY,WV MA,OH,OR,RI,MT,WY,WA,MI DXCC W,VE,JA,PY,ZL,TX9 |
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Re: Accurate way to measure RF power??
Hello Bill,
I almost did not want to respond because I consider myself a "novice" still around all these experts.? But I decided to write anyways.? Just consider what I say with a grain of salt.
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I used to get a lot of private emails from a big Elmer on here named Chuck Carpenter (SK).?? He was a big fan of the diode peak detectors and "RF taps" to measure RF power.? I wish I still had his emails.
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Take a look at the RF probe from qrpguys.com
And they have an attenuator at qrpguys.com as well approved by Chuck as well.? The 10/20/30dB 50ohm attenuator.
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kc9on had a smt version of a rf peak detector/dummy load for QRP.? i built it.? my first SMT project.?? Not sure why KC9ON stopped making this kit.
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You probably know this already, so just ignore me for the silly questions:
- Did you compensate your probes?
- Lose connections on the cable?? (has been issue for me in the past)
- Cat or dog bite your cable?? (has been issue for me in past as well)
- 1M Inputs??? (Most scopes do not have 50ohm inputs)
- Probes and Scope on correct setting of 1X vs 10X setting?
- If scope is 100 MHz, are you using 100MHz probes?
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What frequency are measuring?
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Unless, you have 50-ohm inputs, they can only take so much power, so you may need to attenuate via an attenuator.? Best to read the manual to know how much the oscilloscope can take.
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I know in the Electronics of Radio book for NorCal 40A CW Transciever Kit for the Questions.? It wanted to use instead of a probe, a BNC tee - one end to scope and the other to a 50-ohm termination (dummy load).
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73 Daniel KK4MRN
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Re: Is there an easy way to test sa612 smd chips
On Thu, May 22, 2025 at 01:50 PM, Steve Ratzlaff wrote:
I have a number of SMD Signetics SA602A's. I don't want to remove them from the roll, but I do have one free one and one single solitary 8 pin DIP one. The SMD one measures 11.75K DC resistance across pins 1 and 2, while the 8 pin DIP part measures 21.65K. Seeing that Steve's SMD ones all measured in the 11K range, as mine did, I'm wondering if the through-hole ones tend to all measure higher across pins 1 and 2? ?
No particular reason for me asking; I just noticed it. Back to your regular programming :D
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Dave
AA7EE |
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Re: Accurate way to measure RF power??
What type of scope do you have? I have a new Hantek and older Tektronik scopes and both are accurate for the HF bands. I like to use a scope because you can measure SSB PEP power.
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The issue I have with the Tek scopes are the old probes. The clip-on hook adapters make intermittent contact with the tip so I made an adapter to connect the rig and the dummy load directly to the tip and ground sleeve of the probe. If your scope has a 50 ohm input you can attach an attenuator with the appropriate power level and attenuation and bypass the probe. I do lots of portable operation and picked up one of these portable scopes. It is accurate up to 30 MHz. The voltmeter function is helpful but the function generator has a very limited range. Good luck. Mike N2MS On 05/23/2025 4:10 AM EDT Bill <bill@...> wrote: |
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Re: Accurate way to measure RF power??
Hi Bill,
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You didn't tell us what frequency range you were trying to measure, and what power range.? ?This can make a difference in how you can measure accurately.? ?Also, are you trying to measure the RF power that is already being terminated into a 50 ohm load?? ?If you were trying to measure with a 'scope you would have needed to do this as the scopes have high impedance inputs.
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You're attempt with your oscilloscope will work assuming that you're probes are working correctly, and you scope bandwidth is wide enough to measure the RF energy directly.? ?If you have a Rigol scope of something similar, you're scope might have a calibration point on it that you can use to test your scope probe for both amplitude and correct compensation.? ? On the Rigol 'scopes is to the right of the BNC input connectors.? ? It should not be that hard to determine which probes are working correctly.? ?This is a common problem, as probes take a lot of abuse!
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Your idea for using an RF probe is also a good one and allows you to measure the RF energy as a voltage.? ?One thing to keep in mind is that a diode detector provides a peak voltage, which needs to be converted to RMS voltage as part of the power calculation.? ?This is important if you're using a voltmeter (or oscilloscope)? to measure the detector output directly.? ? ?Curt mentioned a circuit by W7ZOI, who is always a great source of information.? ?HIs book Experiential Methods in RF design shows a simple QRP power and an RF? probe on page 1.16.? ? ?W7ZOI also published an accurate power meter in the June 2001 QST that uses a modern logarithmic detector IC for a wide range power meter.? ? I would recommend this article along with the EMRD information as he shows various methods for setting up a power meter into the RF Chain.??
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Let me know if you have trouble finding? any of these references.? ? ? ?
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73
Jim N8CH
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Re: Accurate way to measure RF power??
Bill
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I am surprised with scope probe inconsistency and don't know them well enough to comment. Maybe they are optimal at different frequencies.?
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I built a diode sensor per W7ZOI instructions. It was embedded in a QST Article on a transceiver. Maybe it's also online. Uses a silicon diode for few watt measurements, and if needed a as second Schottky diode for lower levels. I certainly think it's accurate to better than 10 percent mostly determined by diode forward voltage variation. Built with a coax connector for its input. Certainly good for HF.?
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For measuring very small RF power someone designed an accurate with a specific op amp. I sense you don't need it for this application. I recall this was Joe of njqrp.?
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Let me know via direct email ic you can't find it.?
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Curt
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Accurate way to measure RF power??
All,
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???? Would a simple diode detector be a (relatively) accurate way to measure RF power?
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???? I suspect my o'scope is reading RF incorrectly.? I have 4 different x10 probes and with each one I get dramatically different results, up to a 30% difference.? So, I can't trust my scope!!
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???? Thus, measuring RF power presents a problem to me.? I don't have access to any calibrated power measuring devices, but am quite confident of the calibration of my DVM.?
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???? Or, if diode detectors are inaccurate, do any of you have any tried and true ways to measure RF power with a decent degree of accuracy...say within 10%?
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W2EB
Bill Lazure
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uP40 Transceiver
Hi Everyone
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I've been working on a new transceiver project. I was so pleased with the uPDCR (a small phasing receiver with AI voice) that I thought it would be fun to turn it into a transceiver. So I've combined the transmitter section from the iqSDR40 with the uPDCR and built the uP40 (links below).
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I really wanted it to fit into the next size up Hammond case which is 80x54 mm, so the PCB needed to be 80x50 mm. Instead of using the usual bifilar transformers wound on FT37-43 toroids, I thought I'd try a small surface mount common mode choke. Also thought I'd try one of the small surface mount RF MOSFETs designed for VHF, UHF the AFT09MS015N. I was very surprised and happy that all the components fit on the PCB! The uC and PWM filter parts are on the bottom and everything else is on the top. Then I started routing. I've pretty much standardised on using 4 layer boards but it became obvious pretty quickly that there was no way to route some of the longer traces because of the density of the components. OK, so I had a look at prices for 6 layer boards from JLC PCB and it's really not bad. So top layer is for RF signals, layer 2 is ground, layer 3 is for some uC control signals, layer 4 is 5 volts, layer 5 is ground and the bottom layer is mostly for digital signals. All layers also have ground and there are plenty of stitching vias. In the end I got 5 boards for about US$5 (shipped to AU) with a discount applied.
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I built the transmitter section first and tested it with a signal generator. It worked fine. Got 5 watts. So the MOSFET and the common mode choke worked fine at HF!
I also updated the firmware to announce the mode and the frequency step.
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uP40:
uPDCR: iqSDR40: ?
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73, Ian
VK7IAN |
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Re: Is there an easy way to test sa612 smd chips
I found this at Adafruit.com as a soic-8 ic socket
but i am thinking of using as a tester.??
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but this item only works for a size of 200... who knew there are different sizes of soic-8 ICs?
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Here is another one, but it is expensive.
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But if you have a whole bunch you need to test.
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Last time I was considering of buying one, they sold out.? But they are in stock now.
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73 Daniel KK4MRN
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Re: Is there an easy way to test sa612 smd chips
Steve, Yep, you are correct. I guess I lost that memory somewhere. Sorry for the misinformation.? Mike M.? KU4QO? On Thu, May 22, 2025, 4:45?PM Steve Ratzlaff via <ratzlaffsteve=[email protected]> wrote:
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Re: Is there an easy way to test sa612 smd chips
开云体育I tested 7 SMD "NXP" marked 612's just now (old Fluke DMM set to 200 kohm scale): ohmmeter reading across pins 1 and 2:? 11.1k; 11.6k; 11.4k; 11.0k; 11.3k; 11.3k; 11.5k ohms. Steve On 5/22/2025 1:26 PM, Steve Ratzlaff
wrote:
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Re: Is there an easy way to test sa612 smd chips
开云体育Sorry, Mike, that is not correct. That's the input impedance at RF, not the DC ohmmage. The info I gave is correct. Steve On 5/22/2025 1:35 PM, Michael Maiorana
via groups.io wrote:
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Re: Is there an easy way to test sa612 smd chips
Measure 1500 ohms across the input pins (1 and 2) 73 Mike M. KU4QO? On Thu, May 22, 2025, 4:16?PM Doug Hendricks via <ki6ds1=[email protected]> wrote:
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Re: Is there an easy way to test sa612 smd chips
开云体育The early NC40B kit 612s had some defective ones. An easy check we found is ohmmeter across pins 1 and 2. Good ones are in the 10-50 kohm range,? bad ones are open or much higher or much lower. Steve AA7U On 5/22/2025 1:16 PM, Doug Hendricks
via groups.io wrote:
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