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Tnx!

Well, it looks like I can't edit the OP anymore, so here's a new pic. Per Shockwave's observation (many thanks!) I added a .01uF ceramic cap between the input transformer and the circular ground pad around the hole just next to it. As Shockwave said, this allows the transformer to be isolated from ground as far as the DC bias voltage is concerned, while still providing a path to ground for the incoming RF signal.

The wire with clear insulation powers a fan I've mounted on the heatsink. The fan's positive wire is connected to the same pin as the 10W bias resistor, and the negative wire is connected to the same ground as the capacitor described above.

And as a comparison, here's the amp before modification. Sorry about the perspective, I took the before pic awhile back and it's actually a different KL300, but you can see the changes that have been made.

SO, four components and a small amount of soldering later, we have a very inexpensive little class AB amp that has gotten very nice reports on the air so far. Plus if you're like me it's cool that there's a bit of your own handiwork in there.

<blockquote data-quote="eagle1911" data-source="post: 265141" data-attributes="member: 17129">Tnx!Well, it looks like I can&#039;t edit the OP anymore, so here&#039;s a new pic. Per Shockwave&#039;s observation (many thanks!) I added a .01uF ceramic cap between the input transformer and the circular ground pad around the hole just next to it. As Shockwave said, this allows the transformer to be isolated from ground as far as the DC bias voltage is concerned, while still providing a&nbsp; path to ground for the incoming RF signal. The wire with clear insulation powers a fan I&#039;ve mounted on the heatsink. The fan&#039;s positive wire is connected to the same pin as the 10W bias resistor, and the negative wire is connected to the same ground as the capacitor described above.<img src="http://i80.photobucket.com/albums/j191/faze4djs/Stuffs/kl-300pbiasAB2.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />And as a comparison, here&#039;s the amp before modification. Sorry about the perspective, I took the before pic awhile back and it&#039;s actually a different KL300, but you can see the changes that have been made. <img src="http://i80.photobucket.com/albums/j191/faze4djs/Stuffs/kl-300prfdeck2.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />SO, four components and a small amount of soldering later, we have a very inexpensive little class AB amp that has gotten very nice reports on the air so far. Plus if you&#039;re like me it&#039;s cool that there&#039;s a bit of your own handiwork in there.</blockquote>

[QUOTE="eagle1911, post: 265141, member: 17129"] Tnx! Well, it looks like I can't edit the OP anymore, so here's a new pic. Per Shockwave's observation (many thanks!) I added a .01uF ceramic cap between the input transformer and the circular ground pad around the hole just next to it. As Shockwave said, this allows the transformer to be isolated from ground as far as the DC bias voltage is concerned, while still providing a path to ground for the incoming RF signal. The wire with clear insulation powers a fan I've mounted on the heatsink. The fan's positive wire is connected to the same pin as the 10W bias resistor, and the negative wire is connected to the same ground as the capacitor described above. [IMG]http://i80.photobucket.com/albums/j191/faze4djs/Stuffs/kl-300pbiasAB2.jpg[/IMG] And as a comparison, here's the amp before modification. Sorry about the perspective, I took the before pic awhile back and it's actually a different KL300, but you can see the changes that have been made. [IMG]http://i80.photobucket.com/albums/j191/faze4djs/Stuffs/kl-300prfdeck2.jpg[/IMG] SO, four components and a small amount of soldering later, we have a very inexpensive little class AB amp that has gotten very nice reports on the air so far. Plus if you're like me it's cool that there's a bit of your own handiwork in there. [/QUOTE]

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