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Hi, 220pF 73

Paul, As others have recommended I would use the Vishay or Mica Capacitors. I have a Chinese made ATU-100 and run a maximum of 50 watts since I don't trust the quality of the capacitors. Mike N2MS

If you don't want to use leaded SM caps, Vishay makes a nice RF cap in 1111 format that just fits. VJ1111D221KXLAT. That's what I used in 'project overkill'. The relays or the pcb traces will arc

Surface mount silver mica capacitors exist. You have to step up to the larger 1210 size rather than 0805 to get parts that are rated for 500V; the 0805 ones are only rated for 100V. You're unlikely to

its a 220pf 500v silver mica according to the circuit diagram its probably a 220pf ceramic in 0805 size from what I observe of an unbuilt PCB - hth

any idea of the c value?

Hi paul go on digikey and get silver mica caps > 500v .. chinese atus use 50v or 100v versions which fail. 73's Jason 9H5BM wrote:

or where i can find? replacement,nothing on ebay.

Hi folks,i was trying my atu-100 on my doublet/ocfd on 80m,it tuned down to about 1.2-1,then after a min of key down it smoked,heres a pic of the cooked cap,dous anyone know the value and type so i

Hello Yan, do you mean the pad marked in red in the picture below? I don't think that is the fault, it is just where the braid of the cable going to the TRX is grounded. See the pictures below. I was

Hi, everyone. I'm BI6MPW from China. I may have found some problems in the process of learning and making atu10. When I studied this version of PCB of zao, I found a doubt that could not be ignored,

Hi Stefan, I never tried #43 core on 6m band, so its difficult to say. I measured efficiency of different winding styles end even KN5L method shows rapid drop of efficiency above 30MHz. So even if SWR

Hi! I got the PCB's from JLCPCB yesterday, well done. Programmed right away, tested the drivers passively, with 5V source - they work fine and drive relays much beefier, than the ones I will use in

Hi?Russell and Marek, Yes, I still use my 7-band EFHW 99%, because it's so simple, light and efficient and doesn't need an ATU ;-) For the ones that are not familiar, this is the corresponding

Hi Stephan, I bought ATU-10 to play with EFLW antennas. I find LW useful in small spaces like on holidays or short weekend breaks, putting up 20mtr of wire its sometimes tricky in location where you

I have build 49:1 using KN5L method on FT140-43, 2xFT114-43 and FT82A-43 all 28:4 turns. Each one has efficiency over 90%. I rewound all my EFHW QRP transformers and use KN5L method as standard.

Very well noted! Actually selection of tuner architecture should lie in the character of the load itself. Sometimes specific loads will cause much losses in T-networks, and some will not be tunable at

Be careful if you want to use a T-network in an auto tuner. The unloaded Q must be very high, the Q of the T-network loaded by the antenna, on the other hand, very low, otherwise losses due to

Thank you Dave! That is a lot cooler than I thought. -- Colin - K6JTH http://tangokeys.com

Hi Paul, The ATU-100 uses an L-Match tuner with a series inductor “L” and parallel capacitor “C”. The capacitor is connected to either the input side (TX) or the output side (ANT). A simple