--Original Message-- From: jeff millar <wa1hco@adelphia.net> To: David Robbins <k1ttt@arrl.net> Cc: 'Amps' <amps@contesting.com> To: <amps@contesting.com> Date: 15 May 2002 07:15 Subject: Re: [Amps]
//Seems obvious this is NOT a parasitic, it's a product created elsewhere. I've seen this kind of thing many times in densely populated contest stations, and it's often quite surprising what's cause
Amen, Steve. If he tried a dummy load on the amp, and there was no birdie then, it seems to me, it is narrowed down to the antenna system or the ground system. Like you, I have seen many weird thing
In my experiences, loose joints make a plethora of HF harmonics well up into the VHF region. Thus, finding loose joints can be done with a portable FM receiver. Suitable modulation can be 60wpm dits
I've seen similar things. All the more reason to use non-conductive guy cable. Granted, it's not cheap, but I would never go back to steel guy wire. Remote antenna switches are also sometimes guilty
It is virtually impossible to have an HF oscillation problem in a GG amplifier with a very stable tube like the 8877. You also indicated it was level sensitive with a fairly high power threshold, wh
? Good point, Mr. Rauch. A friend runs an amplifier analysis program for an engineering company. He plugged in the feedback-C spec and other constants for an 8877 and he found that it could only osc
Poor connections can generate TVI and RFI, but pieces of wire (even resonant ones) do not unless they have a poor connection someplace. It takes an arc or an unintentional rectifier to cause TVI.73,
Actually 'subharmonic' is a technically valid term. While not often used in hf radio it is frequently used in mathematical contexts when talking about sets of periodic functions, in microwave circuit
Well, I can now say for sure that it is not the amp. I have found that by feeding only the top 6 ele 20m beam and pointing it either due east or west I can generate the f/2 and 3f/2 products with as
Hi Dave, I'm positive you are wasting time looking for non-linear joints producing a F/2 or 3F/2 product. Sub-harmonics are impossible to produce by virtue of a non-linear system. . Look for a mixin
Dave, Just a thought: As Tom suggests, have you checked for signals on frequencies of possible local oscillations that might create the ultimate mixing product that you hear? I'm thinking of sources
Tom, I thought Dave said that the 21 MHz spurious signal tracked his fundamental and held a 3F/2 relationship with it all the way across the 20 meter band. I don't see how a the 14 MHz fundamental be
A possible clue would be to change frequencies and watch the spurious frequency change. Locks at half the frequency are nearly impossible, because the positive peak of the oscillating system would h
Yes, the f/2 and 3f/2 both track the 20m transmitter exactly, so its not mixing with some other signal, its all due to that 20m signal somehow. It is also related to wx somehow. Yesterday when I got
The following is a link to an IEEE paper that I found this morning which talks about (and references) analog frequency dividers. Apparently the application is high frequency (microwave) low power sys
The following is a link to an IEEE paper that I found this morning which talks about (and references) analog frequency dividers. Apparently the application is high frequency (microwave) low power sys