[Heathkit] SB-610 Tone output?

[eugene at hertzmail.com]

Hello all,

My SB-610 on single-tone (1.5 kHz) puts out about 0.1v peak to peak
signal with the maximum setting on the pot.  I am hoping to get about
0.3v peak to peak out of it to satisfy the input requirements of my
transmitter (af input connection).

1. Can anyone tell me if 0.1v p-p max is what I should expect? 
2. What part would I change out to get this up to 0.3v? I tried changing
R405 from 1Meg to 500K (by paralleling another 1Meg) but that just
stopped oscillation. So now I am thinking I should increase R403 from
220K to something higher. Am I on the right track? Or is it possible
that I simply cannot expect that kind of output from the tube?

Thanks!
Eugene