EMRFD Message Archive 14229
Message Date From Subject 14229 2017-08-28 12:04:14 mosaicmerc DIY build of Ebay 45W CW,SSB $14 amp with mods and details. Hi all:
This common $14 kit off Ebay is poorly documented.
I have done a complete LTspice Sim of it and an actual build with new BOM details and calibration guidance.
I hope it is useful in the spirit of DIY.
I can achieve 50W avg output power with proper cooling.
14246 2017-09-03 00:57:08 drmail377 Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. Thanks for posting this. I just ran your sim. Here are some comments & questions:
1. You should include an example .plt file with your sim file-set.
2. Where is the .AC analyses, especially including S parameters? S parameter analysis is a built-in with LTspice. Since your two ports are each terminated in Zo, don't forget to correct your S parm plots by a factor of two. With S parms, breaking out Rser from the input voltage source is really needed so you can see the actual input source node (in other words don't use Rser at all, use a separate part).
3. Seeing a .FOUR plot setup would be nice, especially with and without a standardized LPF. But before you do that you need to slide your .TRAN analysis data capture window down later in time into the steady state region and make sure your time window contains an even number of waveforms (lots of them). Don't forget to turn data compression off.
4. What's up with the unconnected node on C16? The SPICE Error Log picked that up and threw a Warning.
5. Where are The Rser values in the T2 windings?
6. Does the kit from ebay really come with a pair of IRFL014's in the output? If not, what's the original part number?
7. A .MEAS deck is needed to determine the (at least) the actual gain and bandwidth. 1dB compressi
14247 2017-09-03 01:15:40 drmail377 Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. OK, I see an inline annotation to Q1 in the scematic that says "IRP530". Is that the actual part number that came in the kit? Should it be IRF530 instead of IRP530? Tnx, WB4ONA 14249 2017-09-03 10:43:58 Gabriel Nemeth Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. I don't know the kit. However, It is a different part. Be careful. The IRP530 seams to be equivalent to the IRF620. Go through the transistor's specifications in great detail as far as it is applied in the design.
good Luck '73 VE3SLJ, Gabe
14255 2017-09-03 20:48:47 AncelB Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. It is an ongoing project ....so the spice sim can be made more
elaborate, I am not a spice expert though. Please feel free to improve it.
C16 is a DNP part. It's in the schematic because it's on the PCB. The
FETS are IRF530 types.
As it is, I established the basic function with the changes I made. Also
it can assist the DIY builder in tweaking their own design.
I just used similar built in LTspice components, as the models I got for
the actual Power FET semiconductors behaved strangely.
For $14 I didn't plan to spend a lot of time fixing the amp as I just
needed a semi decent 50W HF/RF drive to use for another project which
has me engaged right now.
thx for the advice.
14341 2017-09-20 22:59:33 mosaicmerc Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. Tested the amp to 55W with temperature compensated finals...works fine! 14344 2017-09-21 17:30:38 cwfingertalker Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. Ansel,What bands do you intend to use this amp on? How much drive needed for the typical 45 watts out?Bill N7EU 14353 2017-09-25 08:49:02 mosaicmerc Re: DIY build of Ebay 45W CW,SSB $14 amp with mods and details. I am on 20 meters with it as it has best spectral purity there.
Around 3.7Vpp to get the 45W