I have yet to hear of an Alpha 8874 suppressor go up in smoke. I get plenty of the old ones in here for other problems but suppressors R look as new. Not all 2W carbon composition are the same. Allen
Thats right, I forgot that you use an 8877 which JI says doesnt need any suppressor. There certainly is nothing special or fancy in the AL-1500 layout either. How about showing us your expertise with
The little 3W Matsushita that Measures likes have minimal L but they glow on 10M when using a 3-500Z or similar power tube. So does the #22 ?? nichrome wire. _________________________________________
Interesting. What value are these resistors? Is it just a single resistor per suppressor or multiple? Don't want to fit MF resistors if there might be an issue. Thanks Martin, HS0ZED From: Gudguyham@
Thanks Carl, The suppressors in my 78 are pretty high in value, one measured 88 ohms and the other 2 around 70 ohms. All three look just fine. This amp was a US government employee in a past life and
Why is that impossible? On HF the resistor is almost shorted out by the inductor. The power absorbed will be less then 0.5% of the desired HF with a typical amp. 73 Peter REPLY: Not absorb "any" of t
ORIGINAL MESSAGE: REPLY: Not just 8877s, although that's my favorite. I also have used GS-35B, GU-43B, 4CX1000A and 4CX1500Bs in homebrew amps with no suppressors. All worked fine. Notice those are a
ORIGINAL MESSAGE: REPLY: You answered your own question. Almost shorted out is not the same as shorted out, and .5% is not the same as zero. Some people have a bad habit of taking a very small value
Sure, they might do dissipate some power, but in respect to the desired! HF (1500W) it is negligible. I calculated 1A through 5 ohms at most. 73 Peter it would seem that at the HF end of the HF spect
Why is that impossible? On HF the resistor is almost shorted out by the inductor. The power absorbed will be less then 0.5% of the desired HF with a typical amp. 73 Peter power absorbed by the resist
** A single 3-500 is putting out 600-800W so your rating is cut in half. In addition I disagree with the .5% as its more like .1 to .2% with the typical SB-220 type suppressor otherwise they would ha
I normally do not need a resistor at all. Either, because a parasitic suppressor is not found necessary, or my usual way of blocking parasitics by loading a one turn loop with a ferrite toroid. On so
Interesting about how they do the series capacitor arrangement though I still wonder if it is making it overly complicated. Silver Mica capacitors are about as common as Globar resistors here though
100pf 500V silver micas are about as common as illegal immigrants in the US. All the major catalog outfits stock them. Carl KM1H _______________________________________________ Amps mailing list Amps
Concerning the metal film resistors, I just tried to measure the inductance of several different types of 3 watt 100 ohm resistors that I had, including some that I had successfully used in parasitic
Vic and all, some rough calcs at 100 mHz shows close agreement with your results. Assuming the 12 uH number is a parallel equivalent, converting that to a series form results in 100 +j1.33 or 2.1 nH.
I have been "lurking" on this parasitic suppressor thing but now just have to say something. I want to point out that a good rule of thumb for inductance of a piece of wire is 15 (fifteen) nH per inc
We used to test them in the lab with a VNA, test fixtures, etc, when evaluating components for 500 MHz modems. I wouldnt trust MFJ or any handheld at 150-250 MHz. Carl KM1H __________________________
The mRS miniVNA goes to 180 Mhz. Do you think that it would be acceptable measuring metal film resistors up to its max freq? http://www.w4rt.com/Misc/miniVNA.htm Thanks, Randy AB9GO Randy E. Randall