This problem has developed sometime in the last 6 months or so, but has taken some time to pin down as it seemed intermittent and was being blamed on other things. It did not exist when I first insta
Yeah...move the amp to a different band position.... :) Sorry Dave, couldn't resist. But seriously, if that's an option...while it doesn't fix the 'problem' it will let you treat the symptom in the s
? The AL-1500 is the only mfg 8877 MF/HF amp on this planet that does not use a parasitic oscillation suppressor. A friend modeled the 8877 on a computer program for determining amp stability. In a
Its sounds like the amp is marginally stable, and the input signal is pumping the oscillation. I have seen this kind of behavior in a marginally stable solid state IF amplifier strip that one of our
What do you have plugged into the receive antenna jack on the MP, anything? I've had problems with transceivers oscillating when using separate receive antennas because of poor external antenna port
Frequency division (producing products on 1/2f ans 3/2f etc) is not unusual in solid state PAs, especially using bipolars. It's often self sustaining once started rather than fleeting or transient. I
Hi David First guess is that your FT-1000 has a spur at 7 Mhz and the amp is making the third harmonic. I take it that you are adjusting amp power by reducing drive from the FT-1000? That would make
? 813s don't need a VHF suppressor because they have virtually no VHF gain. However, this is undoubtedly not the case for the 8877. The last time I talked to Mr. Rauch on the telephone, he told me t
Ok, thanks for all the testing suggestions and comments. Below I will try to answer all the questions and suggestions so far. I also find it hard to believe it is produced by the amp, but am running
Okay, I'll ask the seemingly stupid but logical question: What are you using to measure this spur? Have you tried using something else? (That is, if you're using a receiver, have you tried a differen
Hello all: Richard escribió: I'll ask something not directly related with the main thread. I've seen a a friend who made his own amplifier with one 813 (don't laugh, may be qrp for you, but fo
At this point nothing is a stupid question, I am definitely confused. I am using other radios in the shack to measure it. It was first noticed for the bad clicks on 15m. The 15m station has an ft-100
What if the signal is being picked up by one of the other antennas, and some non-linear device (like pin diodes in a QSK circuit) is generating the signal and radiating it? (although why a SUB-harmon
It would now appear that you have narrowed the problem quite nicely. The only thing common to all of the permutations you have described is the antenna system. From the connector at the shack to the
Dave, When you said "with and without" the ICE bandpass filter, did you take it completely out of circuit for the "without" portion or just switch it to the bypass mode. The LEDS on the ICE front pan
David, when you made the comment that you used another amp and had the same problem, I begin to suspect something External to your amps, as in something that may be acting as diode and generating spu
45MHz means he has a long wire from the Tune-C to the 813 anode connection. - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, www.vcnet.com/measures. end
-- Dave, What are you listening to the spur on? Could it be generated in the receiver? When you listen to it is it a clean carrier or is there any other modulation on it? Try turning off the computer
It's possible to generate a 1.5x multiplier with a nonlinear C or L. I once designed a 144 to 226 multplier with a varactor diode and some tuned circuits. The circuit contained an idler tuned circuit