Homemade (Palomar 450fet hd) issues

[Uncle Ronnie 336]

Not getting the power output I should be out of this only around 200, I have a 100 w single mosfet driver amp that I already built and works like a champ and anything above 60 makes the audio crunch and I'm only getting around 200 off the top. I got the input match good and messing with caps I was only really able to maximize it to where it's at though. Kinda stumped at the moment. I can tell these mosfets are drying juice because the lights flicker a little bit when I talk into it with the driver on but something definitely ain't right

 

[Uncle Ronnie 336]

Oh, and I used new 9530s
Usually on my cheap mfj meter RMS power is about a quarter of the peak almost every system and despite only reading 200 on the top end my RMS power is going up to about 90. Normally that would only be around 50 RMS

 

[nomadradio]

A 'scope would reveal that the amplifier is acting like it's over driven and the modulation peaks are being "flat-topped". This puts the valleys in your RF envelope closer together, making the average power appear higher than normal.

Usually makes the audio quality somewhere between brown dirt and black dirt.

73

 

[Uncle Ronnie 336]

Yeah I just went through and tested all the transistors. All of them tested good. It's definitely a tuning issue somewhere

 

[Uncle Ronnie 336]

So I was only able to get 250 off the top of this thing, and I found that there is an internal mismatch with the relay. Tried using caps to tune it out but I think there is just too much power loss in and out there. It's a pretty heavy duty relay

 

[Uncle Ronnie 336]

I am using RG 188 mil spec Teflon coax that can handle somewhere around 1k and I tacked a 50 ohm resistor on that and tested the main run of it that I have and the antenna analyzer is reading perfect so that's not the issue. Pass through readings on my cheap Chinese antenna analyzer reading around a 2:1 at somewhere around 100 ohms when I don't pad it out with caps