Whats inside a Feeltech FPA-301? Better than Juntek DPA-2698 ?? - Page 1
Forum section: electronics / testgear

author: Noy
author_rank: Frequent Contributor
timestamp: November 02, 2020, 08:30:19 am
content: Hi boys and girls :-DI'm searching for an power amplifier for my Rigol MSO5000 AWG.Currently there are 3 options:OPA541 "Evalkit" from Ali (smallest BW / highest current):https://de.aliexpress.com/item/33001238633.html?spm=a2g0o.detail.1000060.1.146e24afew9ZG4&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=ef788863-40a5-4ec3-b430-e048d9ff13ad&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:ef788863-40a5-4ec3-b430-e048d9ff13ad,tpp_buckets:668%230%23131923%2393_668%23808%233772%23904_668%23888%233325%238_668%234328%2319935%23698_668%232846%238111%23445_668%232717%237565%23788_668%231000022185%231000066059%230_668%233468%2315608%23167Juntek DPA-1698 / 2698 (currently my prefered device i think):For 2698 there is already a thread with the internals. I think DPA-1698 is a kind of this design with less capaple output stage?Feeltech FPA-301 (different verions available 5/10MHz / 10/20W):Whats inside the devices? Can anybody provide pictures / informations? Reviews?Which ones do you think ist best bang/buck?

author: Noy
author_rank: Frequent Contributor
timestamp: November 02, 2020, 09:50:43 pm
content: Nobody knows whats inside? / If they are good / meet the specs?

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: November 03, 2020, 03:17:30 am
content: I'd be curious too. DPA-2698 is described herehttps://www.eevblog.com/forum/testgear/juntek-dpa-2698-10mhz-signal-amplifier-digilent-analog-discovery/I am suspicious of the power supply, but the output stage seems fine.I suspect DPA-1698 probably has OPA541 or similar.Btw, there are inexpensive amplifiers like that with a linear power supply on e-bay, search for PASCO CI-6552A POWER AMPLIFIER.Feeltech FPA-301 power spec is clearly off. Even taking peak values of 1A and 14V peak one does not get 20 W. I suspect its similar to DPA-2698 except all 4 output buffers are in parallel.

author: Noy
author_rank: Frequent Contributor
timestamp: November 03, 2020, 07:29:01 am
content: Thx for the hint. Unfortunally i'm located in germany and in eBay the amplifiers are all US devices. Shipping costs more than 50€ + tax..The PASCO CI-6552A looks like it is only kHz bandwith. I need at least 5Mhz.Hm i think i will buy the DPA-2689 its cheaper than FPA and as long as i dont know whats inside it could be more worse than DPA.Or i will build it my own but i think this would be more expensive than buying / modding for example add another connector to dpa to use my bench supply if its to bad inside.

author: Tjuurko
author_rank: Regular Contributor
timestamp: November 04, 2020, 01:39:00 pm
content: Quote from: maxwell3e10 on November 03, 2020, 03:17:30 amDPA-1698 collected from XL6012E1 (XLSEMI) and two LM1875C (UTC).

author: Noy
author_rank: Frequent Contributor
timestamp: November 04, 2020, 07:15:17 pm
content: THX. I took the 2698 for 53€ shipped within EU (no tax will be added).Because it was to unclear whats inside the FPA ones. I only found a review where someone said not the full stated bandwith is reachable. And because of the "cant be true" wattage i thought "better catch the small bird in your hand than the bigger bird in your roof... " or something like that :-DMaybe i will add a connector for direct lab power supply input and maybe both channels can connected with a switch or something to get 1A for 1 channel use...

author: Vestom
author_rank: Regular Contributor
timestamp: December 27, 2020, 11:50:22 am
content: Could you provide a link to where to find it for 53€ within EU?

author: Noy
author_rank: Frequent Contributor
timestamp: December 27, 2020, 02:05:57 pm
content: Of course:€ 46,69 30%OFF | DPA-2698 High Power Dual Channel DDS Funktion Signal Generator Power Verstärker DC Power Verstärker 0-10MHz EU/ UNS Steckerhttps://a.aliexpress.com/_BUkKJsOrdered from poland took 1 week.As i ordered it was a bit off (53€)

author: mawyatt
author_rank: Super Contributor
timestamp: December 27, 2020, 02:32:56 pm
content: We have the DPA 1698 which is based upon the LM1875, not bad for the $ IMO.https://www.eevblog.com/forum/testgear/awg-buffer-amp/Please report what you find with the DPA-2698.Best & Happy Holidays,

author: Noy
author_rank: Frequent Contributor
timestamp: December 27, 2020, 05:23:12 pm
content: It is already clear. Take a look at the link posted in the first post.

author: mawyatt
author_rank: Super Contributor
timestamp: December 29, 2020, 01:09:47 am
content: Any measurements on the DPA-2698 like the Input & Output Open Circuit noise properties? How much of the SMPS waveform is on the output?Best,

author: Noy
author_rank: Frequent Contributor
timestamp: December 29, 2020, 11:52:18 pm
content: Ah okay, maybe i have time next week to do some measurments.Will also modify the device with a dpdt switch (if this fits into the case..)to combine the 4 buffers for 1 channel. Output from channel 1 opamp connected to all 4 buffers and output from the buffers connected together to channel 1 BNC. To have 1 channel up to 10MHz with close to 1A.

author: mawyatt
author_rank: Super Contributor
timestamp: December 30, 2020, 03:54:40 am
content: The reason I ask is the 2698 appears to use the same XL6012 as the 1698 which is a SMPS controller that runs at ~180KHz. The 1698 uses separate Pi LC filters (on +26VDC & -26VDC) for each amplifier (LM1875), so 4 Pi LC filters total. The images of the 2698 show a Pi LC filter for +supply and -supply for both amplifiers, so only 2 Pi LC filters.I'm considering designing & building a dual amp unit that can support higher voltages an currents (~120Vpp @ ~3A), and maybe even a higher frequency dual amp also. I really like the case Juntek is using, but can't find it.Edit: We've designed a couple Dual Amps based upon the LM3886 and TDA7293 power amp chips. Both designs utilize the XL6012 SMPS to produce +-40~60VDC to allow higher voltage and current outputs (short term). Both chips feature over current and temperature protection, the TDA7293 provide an output to indicate such, and both have "soft start" capability to reduce turn on glitches. Resettable fuses are incorporated on the power supply input (12-24VDC) and each power amp output. Over-voltage protection on the inputs and outputs should help during actual use. The voltage gain is fixed at 5X and bandwidth is limited by the chips. Two designs were created to compare the these two chips which are specified for audio amplifier use, so hopefully some testing will give an indication how well they performance as an AWG expanded output amplifier.We also create a 150~180Vpp dual amplifier for very high voltage requirements at lower power levels.The PCBs layouts were based around the JunTek 1698 case and should fit in the this case or another available from eBay.Not sure yet which designs will be released for fabrication and test. Attached are images of the 3 PCBs for the Dual Power and Dual HV Amps. First is for LM3886, 2nd for TDA7293 and last is HV version.Best,

author: YqHFXa01
author_rank: Newbie
timestamp: January 24, 2023, 12:12:42 pm
content: In fact there is an amplifier with higher performance than your work!https://www.diyaudio.com/community/threads/winfields-100w-dc-10mhz-1000v-us-amplifier.287023/If you can, please post the schematic and BOM list.I intend to compare the two.