Note this FT-726 modification for the PB2441A module (Rx Unit) http://www.agder.net/la8ak/b51.htm
Yaesu FT-726
LA7BI wasn't satisfied with the audio quality of his FT726. First he tried to improve the AGC, and some improvement was found, but still it was some distortion. The datasheet for uPC1037H (Q13) was studied and it seems that the operational voltage on PB2441A No.20 was too high. The same device is used in other transceivers like Icom IC-740 without any problems. The resistor R83=56 ohm was increased to 120-150 ohm for +6V voltage on the IC. The quality is much improved. On later transceivers like Yaesu FT-736 they've gone back to the conventional ring modulator, obviously aware of the problem.
Sent from iPad Air
On Feb 3, 2018, at 11:23 PM, Gregory Beat [email protected] wrote:
Yes, Consolidated Electronics in Dayton, OH area has that NEC 7-pin SIP part. Look for eBay reseller: ceitron
Here is the NEC uPC1037H data sheet http://www.datasheetarchive.com/dlmain/Datasheets-16/DSA-317957.pdf
w9gb
Can replacement uPC1037H's be found.