Holden,
My recent experience with the uhf MOSFET was the same as yours.? The ¡° Final Idle Current¡± setting was negligible.? UHF power out was around 10W.? I removed 401 and it tested bad. ?
You have to be careful with the low priced eBay sellers from China.? I have received bad MOSFETS in the past, but they quickly refunded. ?
For the RD60HUF1 I found for around $20?from the seller MTX.? It took about 3 weeks to arrive, but the part was in new condition.? The uhf idle current setting is now correct and UHF power out is correct.? I¡¯m glad you got the ribbon cables working and good luck fixing the UHF side.
Tommy KF4RWG
I think I have sorted out the ribbon cables now.? Setting the bias current seems to work okay for all bands except UHF.? I have verified that the bias voltage reaches Q401-G, but maxes out at 0.98 V about 3/4 of the way up the scale.? On the other side of the 100 ohm resistor it's well above 2V at the maximum.? I verified that the other transistor terminals are at 13.3V and zero, as they should be.? Does this mean that my RD60HUF1 is shot??
The radio does give up to 6W output on UHF.? Could this be power from the driver that's being shoved through the failed Q401?
It looks like I can buy a claimed new transistor at AE for $25 USD or from ebay for a bit more.?? Has anyone here bought one that worked?? Is there a suitable substitute transistor I could buy from Mouser or Digikey?
Cheers,
Halden VE7UTS
