ARRL2011 HANDBOOK article " NEW 250 Watt 160 to 6 meter linear amplifier "

[W9RAS]

ANYONE ELSE building the "New 160 to 6 meter 250 watt amplifier " using VRF151 RF mosfets? in the ARRL 2010 and newer handbook I am building one of these and I had hoped to find a forum or website with info on it from other builders . I am experiencing difficulty with the PA current display the rest of the amp appears to work fine . You can contact me direct at mooo46@yahoo.com I check that email often thats three OH's in the address not zeros the XYL loves cows HI HI . TNX DE 73 Bob W9RAS

[K9FV]

Bob, I'd sure like to chat with you some on the amp - after reading your post I've been reading that article myself - There seems to be some discrepancies between the schematic, the BOM, and the article. Since you've got the PA portion going, you might be able to answer my questions.

Did you happen to take any photos of the board before populating it? During your construction?

73 de Ken H> K9FV

[K9AQ]

Bob,

I build the amplifier controller for my EB104 amplifier and had a similar problem with the current measuring. I found that the op amp used for the current monitoring saturates as the voltage drop across the current sensing resistor increases. It saturates well before operating current levels. I adjusted the resistance in the voltage divider circuit for the op amp and also decreases the feedback resistance to lower the gain. In retrospect all you need to do is change the voltage divider values. I am now getting a proportional output from the op amp that I can use for current measuring. I am not howver using the LED displays. Instead I am feeding the voltage from the first portion of the op amp to Wavenode.

I don' t know if this is the problem that you are seeing, but I couldn't get the circuit do work with the values in the handbook.

Don
K9AQ

[AB0DH]

I am building it also. I have the controller and filter finished for the three bands I am using most.
I need to build the PA and test the controller.
Bill AB0DH

[WA4JEA]

Good morning!

I hope you don't mind me bumping this thread, but I am curious if anyone has been able to solve the issues noted earlier. TNX!

73,

James WA4JEA

[KD0CAC]

I would like to see the traffic stay here for all to read , rather than go off site ?
Thanks
John