Hafler Page

 

This is a compilation of my experiences with the Hafler P3000 and P9505.

The best info on these amps is found at www.w1vd.com and www.w1tag.com . Go there first and then read below as a supplement.

 

P9505 Notes:

 Caution: Not all 9505 schematics and units are the same. My 9505 component designators are different from the schematic on the W1VD site. I did find a very hard to read schematic that does match my unit.

 John (W1TAG / WD2XES) and myself exchanged a number of emails the other night and determined that there are three different models of the 9500/9505 amplifier. The C15 cap designator talked about at the W1VD page is different in each. Considerer yourself warned. Mine is apparently the old 9500 model but has a front panel that says 9505.

 The bias pots in my 9505 were painted over so that they could not be adjusted. I measured them in circuit and they appeared to be bad. Purchased new ones. Upon removing the old ones, they were indeed bad. I installed the new ones and then they checked correctly in circuit. The 200 ohm pots are Mouser part number 531-PT10V-200, Mfg part number PT10LV10-201A2020 made by Piher.

 If you ae using a K3s in transverter mode, be advised thee are no lowpass filters out of the K3s. Every harmonic is well represented. I needed to put in a bandpass filter after the K3 to calm down the Hafler. QRP Labs makes a cheap and simple lowpass filter system for 2200 and 630.

P3000 Notes:

 Repaired mine and it was relatively painless. Bad FET. Bias did not need adjusted. FET are readily available from eBay and can even be bought in pairs.