Alternative for Mini-Circuits ADTT-1? - Page 1
Forum section: electronics / projects

author: mrflibble
author_rank: Super Contributor
timestamp: March 17, 2013, 10:06:22 pm
content: As per subject, I'm looking for an alternative for the Mini-Circuits ADTT-1. While the ADTT-1 is nice, for people in Europe getting mini circuits parts in low quantities is not all that easy. So I'm looking for something withroughlythe same specs, and is easily available. Preferably something that's stocked by Mouser or Digikey. It doesn't even have to be exactly the same as the ADTT-1, as long as it's reasonably flat from say 1 - 100 MHz.It basically for a 50 ohm line driver for the AD9913 current dac (complementary outputs).Any suggestions much appreciated!

author: joelby
author_rank: Frequent Contributor
timestamp: March 18, 2013, 02:32:10 am
content: How low are you talking? In the past, Mini-Circuits USA have been happy to send stuff to me (in Australia) via USPS, which was a lot cheaper than the default fast courier option via low earth orbit. You could also try eBay to see which spares people are selling cheaply, and see if they are suitable for your circuit.

author: mrflibble
author_rank: Super Contributor
timestamp: March 18, 2013, 03:06:35 am
content: Since this is for a prototype ideally I'd get 3. One to screw up, one for proper use and one spare. The number ordered of course would depend on pricebreaks etc, but 3 for now, and depending on how things work out I could use more later.As for ebay, heheh, yes, already doing that. And as always ... I did find some fun items that I can use in other projects (you know, the distracting-you-from-this-project type of project), but I did not find a close enough match to this one. There's several almost-matches available without center taps, but the center tap on the primary side would be quite handy...How much was shipping & handling etc for you? Also, unit cost compared to their @20 quote?

author: mrflibble
author_rank: Super Contributor
timestamp: March 19, 2013, 11:16:22 pm
content: Well, I decided to drop the transformer... all in all too much hassle for now. So I put in an AD8055 with a bit of gain. So now it's an easy to obtain part with as added bonus that I can now sweep the AD9913 from DC up to 100 MHz or so. Think I'll put the f-3dB at about 96 MHz.I'd still be interested in how to get low quantities of mini-circuits goodies for later projects, but for now problem solved.

author: nctnico
author_rank: Super Contributor
timestamp: March 20, 2013, 01:01:29 am
content: I order Mini Circuits 'stuff' from their office in the UK. No problem at all.Besides that you may not need the transformer at all. You can probably use the single ended output with a capacitor in series.

author: mrflibble
author_rank: Super Contributor
timestamp: March 20, 2013, 01:14:00 am
content: Quote from: nctnico on March 20, 2013, 01:01:29 amAh, thanks for the tip, I'll take a look at that. Incidentally, did they require a VAT number?QuoteUsing it single ended would be a bit of a waste of the nice complementary current outputs... But you're right in that I don't need the transformer, as I have plonked in an AD8055 and use both dac output pins.

author: JackOfVA
author_rank: Unknown
timestamp: March 20, 2013, 01:26:50 am
content: Coilcraft has a line of transformers that's worth looking at.www.coilcraft.comand they are very good about sending samples, at least to USA addresses.For really demanding RF work where extremely low levels of intermodulation distortion is required, I've found Mini-Circuits superior to the same spec (frequency response and power rating) Coilcraft product, however.

author: mrflibble
author_rank: Super Contributor
timestamp: March 20, 2013, 01:41:14 am
content: Actually I did try to find a coilcraft part similar to the ADTT-1 at Mouser, but no luck. It could very well be that I overlooked it, but I'm not that familiar with all this RF biz. Is there a coilcraft part that springs to mind (he asked hopefully)?It would be fun to make 2 varieties, one with the AD8055 output stage, and one with a transformer. And then see what we can see...

author: joelby
author_rank: Frequent Contributor
timestamp: March 20, 2013, 04:25:52 am
content: It's still not fabulously cheap - last time I ordered some stuff, the parts were $167 and shipping via USPS was $36. You might want to experiment with a US freight forwarder. Or do what I did and just buy heaps of stuff that you may or may not ever actually need

author: JackOfVA
author_rank: Unknown
timestamp: March 20, 2013, 11:51:58 pm
content: Quote from: mrflibble on March 20, 2013, 01:41:14 amCoilcraft sells directly, not through a distributor such as Mouser. But if you order via the Internet, there's no minimum purchase volume. And, they are very good about free sample at least for domestic US addresses.I assume you mean an ADTT1-1+ as there is no ADTT-1 from Mini-Circuits from what I can see.Coilcraft's surface mount transformer index page is athttp://www.coilcraft.com/wideband.cfm-- one possible candidate is the PWB-1-CL.1:1 winding ratio, primary and secondary both center tap, both surface mount (but are mechanically different) and similar frequency response. (PWB-1-CL has same upper limit of 300 MHz and the lower limit is better at 100 KHz than the ADTT1-1's 300 KHz.)I say "better" for the lower -3 dB point, because in most cases an extended frequency response is not going to get you into trouble. But, most <> always.

author: nctnico
author_rank: Super Contributor
timestamp: March 21, 2013, 12:12:46 am
content: Quote from: mrflibble on March 20, 2013, 01:14:00 amComplementary outputs are only useful if you connect them to complementary inputs. In other situations: don't bother. I played with this recently. It is said a transformer (balun) can be used to reduce 2nd order harmonics. Unfortunately my measurements told me it didn't make any difference at all.I don't know if Mini Circuits UK requires a VAT number. I have one so I guess I just send it to them.

author: mrflibble
author_rank: Super Contributor
timestamp: March 21, 2013, 01:27:35 am
content: Quote from: JackOfVA on March 20, 2013, 11:51:58 pmWell ...http://www.mouser.com/coilcraft/http://www.coilcraft.com/general/sales_eu.cfmQuoteYes you're right, I meant the ADTT1-1+. Thanks for the PWB-1-CL tip.I just checked, andaccording to Octopartthat specific part in only available from Coilcraft direct. Bummer. So just for the fun of it I tried to order some to see what the total cost would be, and they justhave to havethe webshop feature I frigging hate.First order, then payment info and only THEN can you see shipping cost & options. What is this, the dark ages? All I could find on their term & conditions page was $10 handling fee for orders under $100, but no mention of shipping cost. Unless by handling they mean shipping & handling, but I doubt it.

author: mrflibble
author_rank: Super Contributor
timestamp: March 21, 2013, 01:32:48 am
content: Quote from: nctnico on March 21, 2013, 12:12:46 amCan you give more specific details? Otherwise it's a bit anecdotal... But you do raise a good point, and I made a note of it to check the difference. With the current AD8055 schematic I use both current outputs, but it easy enough to make this optional by just swapping a resistor from location A to location B. And then do some sampling + Fourier to see if there's any difference between the two.