EMRFD Message Archive 14309
Message Date From Subject 14309 2017-09-17 11:15:40 bwbangerter AD8307 based power meter
I am planning to build an AD8307-based rf power meter, as many others have done. To this end, I bought ten of these chips, from China, on ebay, at a price that seemed too good to be true. Alas, they are certainly not what they are claimed to be - no surprise. The AD9308 from Mouser or Digikey in unit quantity is $13 and change. Ouch. Has anyone found a less costly yet reliable source for this part?
14310 2017-09-17 12:39:51 Gary Re: AD8307 based power meter Are you sure?My chinese ones worked fine.73,Gary
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14311 2017-09-17 12:59:45 Phil Sittner Re: AD8307 based power meter
I can second Gary's comment having made purchases three of four times and all of them performed well.
14312 2017-09-17 16:52:47 bwbangerter Re: AD8307 based power meter It appears I spoke too soon. I purchased ten parts, in SOP-8 packages, in tape and reel. I mounted two parts on dip carriers, using antistatic procedures and a grounded soldering iron. In my test circuit, the first sample gave an output of ~ 200 mV independent of rf input level (below 0 dbm) and the second gave 0 mV. After seeing your responses and being encouraged to try another sample, the third time was the charm. That one performed perfectly. I'm pretty sure I handled all three samples in the same way. Odd.Ben, K0IKR 14313 2017-09-17 18:59:37 Gary Re: AD8307 based power meter I would check the soldering. I have had probs myself! My old eyes!73,GaryWB6OGD
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14314 2017-09-17 19:09:05 Ken Chase Re: AD8307 based power meter Yes the chinese ones do work, at least the 30 I bought for a buildathon.73VA3ABN 14315 2017-09-17 20:21:32 Dana Myers Re: AD8307 based power meter 14316 2017-09-17 20:27:50 K5ESS Re: AD8307 based power meter
I think why so many of these parts are available at very low price is that they were manufactured some time ago and are not ROHS compliant. Large manufacturers can’t use them if they have to meet ROHS requirements.
14317 2017-09-17 20:33:47 DuWayne Schmidlko... Re: AD8307 based power meter
One of the explanations I read was that many of these type parts are not RoHS compliant, and they are were not able to sell them to new equipment manufactures doing business with EU countries. Another is that they were left over from manufacturing runs and sold to resellers. Either way I am not complaining about the ones that I have gotten for a fraction of the normal price.
14318 2017-09-17 20:38:40 Dana Myers Re: AD8307 based power meter 14319 2017-09-17 20:39:16 Dana Myers Re: AD8307 based power meter 14321 2017-09-17 21:21:30 K5ESS Re: AD8307 based power meter
ROHS compliant means (maybe among other things) that there is no lead in the product. These cheap items are electrically identical to ROHS compliant parts but the leads are not tinned with lead bearing solders.
14322 2017-09-17 21:47:09 DuWayne Schmidlko... Re: AD8307 based power meter
The parts were within spec when manufactured, but may have been manufactured before the RoHS requirements. The issue with non RoHS is usually that the leads are tinned with lead, but that does not make much difference to most hobbyists. Some of these are from auto insertion tape reels. The manufacture may have had an order for 2000 items but had to buy a reel of 2500 parts to get a price break. After the run they sell the unused parts to re-sellers who cut the tape reel in to small lots, and sell to the hobby market.
14323 2017-09-17 22:02:35 Dana Myers Re: AD8307 based power meter 14324 2017-09-17 22:19:28 DuWayne Schmidlko... Re: AD8307 based power meter
Another thing specific to the AD8307, is that it is a fairly old device. For most new applications it has been replaced with the AD8310. Which has slightly different but mostly better overall specifications.
14325 2017-09-18 00:30:40 gi0gdp Re: AD8307 based power meter Hi Ben,I'am fairly certain that AD make a point that if the at rest output voltage is greater than 200 mW it'sbecause you have a bad pcb layout. Where all 3 built on different chip carriers?, the thing is the problemcould equally have been with decoupling caps,GeoffGI0GDP 14326 2017-09-18 03:44:18 Steve Dick Re: AD8307 based power meter No, but if you’re starting from scratch and making a new layout, you might want to consider using the AD8310. It only cost $9.82 instead of $13.14. It is a newer generation device, having a 95dB dynamic range and a built-in output buffer amp with better linearity at slightly less bandwidth. It has DC to 440 MHz operation, ±0.4 dB linearity compared to the AD8307, which is spec’d at DC to 500 MHz operation, ±1 dB linearity Unfortunately though, it does not have the same pinout as the AD8307.Steve K1RF 14327 2017-09-18 13:36:10 byteboy12 Re: AD8307 based power meter A complete module:
Henry - PA0HJA
On 18-9-2017 12:44, 'Steve Dick' firstname.lastname@example.org [emrfd] wrote:
No, but if you’re starting from scratch and making a new layout, you might want to consider using the AD8310. It only cost $9.82 instead of $13.14. It is a newer generation device, having a 95dB dynamic range and a built-in output buffer amp with better linearity at slightly less bandwidth. It has DC to 440 MHz operation, ±0.4 dB linearity compared to the AD8307, which is spec’d at DC to 500 MHz operation, ±1 dB linearity Unfortunately though, it does not have the same pinout as the AD8307.Steve K1RF
14328 2017-09-18 15:55:33 Steve Dick Re: AD8307 based power meter That AD8307 module is an excellent value and the AD8307 is already soldered in for you. Just be cautious of the following: Depending on vendor, the input terminating resistor may be 100 ohms instead of 50 ohms. Measure it with an ohmmeter. If it is 100 ohms, parallel it with an 0805 size SMD 100 ohm resistor and verify the parallel combination is 50 ohms. Or just replace with a 50 ohm resistor. The board also does not have output buffering if that is needed in your design.-Steve K1RF 14330 2017-09-18 16:56:57 K5ESS Re: AD8307 based power meter
The module is actually an AD8310 module which I believe incorporates an output buffer on the chip.
14331 2017-09-18 21:47:37 bwbangerter Re: AD8307 based power meter I want to thank everyone who has contributed to this thread. I appreciate your comments and suggestions, and believe I have learned quite a lot about the sources of the attractively priced parts available from Asian vendors. The two failed parts may have been outliers, and perhaps victims of my mishandling. I now have several AD8307 chips that are working properly, and my project is moving forward!Ben, K0IKR 14332 2017-09-19 03:39:43 Steve Dick Re: AD8307 based power meter Thanks Mike – missed that. Think I’ll buy one to try out 14333 2017-09-19 04:03:58 Steve Dick Re: AD8307 based power meter The seller for that AD8310 module, Ali Express, wants your cell phone number or doesn’t let you proceed. I don’t like that. Ebay also has it. There are 7 listings. Six of them all have the same blurry picture of the module. One seller has an in-focus picture but is charging twice as much as the others. I went with one of the ebay ones.-Steve K1RF 14339 2017-09-20 20:35:47 Jim Strohm Re: AD8307 based power meter Jim N6OTQ800-555-1212 is a perfectly good phone number to give out.Steve,How do alibadbad verify your celphone number?
14340 2017-09-20 21:46:30 Phil Sittner Re: AD8307 based power meter
I have had requests for my phone number when ordering PC boards from offshore vendors. They provide the number to DHL for notification purposes. Is it possible that the same condition exists in your case?
14342 2017-09-21 11:42:36 Jim Strohm Re: AD8307 based power meter Jim N6OTQExcept to sell it to the phone SPAMmers, of course, who pay good money for live numbers when bundled by the millions.Does DHL actually come to your shipping address to deliver, or does the package show up in your mailbox?USPS doesn't care about your phone number for routine deliveries, and anything that ends up in the hands of USPS -- the original shipper's chain of custody ends when the packages goes into USPS' hands so they would never need your phone number.
14343 2017-09-21 12:47:28 Phil Sittner Re: AD8307 based power meter
DHL does actually show at your doorstep and calls prior to attempting the delivery. They typically make the delivery one day prior to what they tell you.
14348 2017-09-23 03:33:04 Steve Dick Re: AD8307 based power meter Hi Jim. The point is, They shouldn’t be asking for one to prevent ordering to proceed. It should be an optional entry, or they shouldn’t be asking at all. 14349 2017-09-23 09:17:43 Raj Re: AD8307 based power meter Here in India/Asia:
They ask for it to message you the order details. Non availability or delays or refunds etc.
They print it on the label for the delivery chaps to call you if they can't find you or no one is home.
If there is a customs problem they call you.
Generally speeds up things!
At 23/09/2017, you wrote:
Hi Jim. The point is, They shouldnât be asking for one to prevent ordering to proceed. It should be an optional entry, or they shouldnât be asking at all.
14350 2017-09-23 10:00:51 Jim Strohm Re: AD8307 based power meter Jim N6OTQIt is worth mentioning, back in the 80s when I sold computers over the phone, I did have a few good customers in 90210.And for the "mortar and bricks" retailers who need a zip code at the checkout register, if I'm not a frequent customer with them, I give them "90210."Hmm, they "need" a phone number. That's kinda like requiring an email address when one is unnecessary. For that, I always give something like "email@example.com" or "firstname.lastname@example.org," both of which resolve as "good" email addresses, even though both merely loop back to the local console of the idiots who "need" an email address.Thus, 800-555-1212. Or the number of the local McDonald's. Or the switchboard at Congress.
14351 2017-09-23 19:13:46 augustinetez Re: AD8307 based power meter We're starting to get a few businesses in Australia that are asking for phone numbers etc.I flatly refuse to give it to them and make them the offer of selling me the item without those details or losing the sale altogether.Can't say that I have struck it in online purchases yet, but my policy is not to deal with places like that.Terry VK5TM