From: Cecil_A_Moore
Newsgroups: rec.radio.amateur.misc

Subject: Ramsey FX transceiver kits

Date: 8 Jun 93 22:20:07 GMT

Organization: ucsd usenet gateway

Lines:29

Message-ID: <930608142007_2
Nntp-Posting-Host: ucsd.edu

Originator:daemon


For all you Ramsey FX transceiver kit owners, here are some needed

modifications.



1. How to cure the transmit audio problem.



Ramsey engineers forgot to put load resistors on the outputs of the

LM324 so above a certain level the transmit audio has cross-over

distortion. Install a 10k ohm resistor from U4 pin 1 to ground and

another 10k ohm resistor from U4 pin 7 to ground.



They forgot to put in a transmit audio gain control for loud mouths,

like me. Replace the audio gain resistor, R58, with a 2k ohm pot which

allows gain control so loud voices do not saturate the op-amps.



2. How to cure the squelch problem.



The squelch circuit does not have enough hysteresis.



Turn R24 around so the bottom is where the top used to be. Solder the

anode of a 1N34A to the new top of R24 and solder the cathode of the

1N34A to where the bottom of R24 used to be. Solder a 10k ohm resistor

from the anode of the 1N34A to +5v (top of R11).



This allows pin 10 of U1 to swing 0 to +5v like it was designed to do,

instead of swinging 0 to 2.7v with not enough hysteresis.



73...KG7BK



Cecil_A_Moore