On 11/1/2019 5:39 AM, W9GY wrote:
Hi Bob, got same issue on mine. Q11 get real hot real fast in tx. I'm awaiting some FETs to arrive before additional troubleshooting. Please keep me in the loop as to what you find. -Hi Jeff,
You bet. The only one I've heard was WA8SAJ's and it sounded good thru a linear.
When I first noticed that Q11 was burning up, I saw that the tab of Q12 might have contacted Q11's heatsink. But while I was waiting for replacement FETs to come I realized the drain of Q11 and Q12 are connected together in the circuit anyway so it wouldn't have mattered if they were touching.
So we both received defective PC boards it seems. The more I try to understand what's going on with this modulator the more confused I get! A complete set of voltage measurements from key nodes - each terminal of all active devices at a minimum - would be a big help.
73, Bob W9RAN