[ARC5] The value of MO and PA tank components.

[AKLDGUY .]

The BC-457 (4.0 - 5.3 Mc/s) can be brought down to cover
the 80m band very simply by resetting the existing padding
capacitors that are already in the set. I know it's possible
because I did that with my very first set (BC-457) in 1967.

With the 1625 plate & screen supply disconnected, I set the
dial to 4.0 Mc/s (PA and VFO caps fully meshed), then
unlocked the padding cap on the VFO and meshed it more
fully until the VFO signal came down to 3500 KHz.

Then I switched off, unlocked the PA tank padding capacitor,
reconnected the PA plate & screen supply, switched on again
and with the transmitter operating into an antenna, meshed
the padding cap more fully until the plate current dipped (still
at the same 4.0 dial setting). Small adjustments were needed
to the capacitor's setting later until I was satisfied that it was
correct at various tuneup conditions.

I forget how good the tracking was across the ZL band,
3500-3900 KHz, but I was able to use that transmitter up
and down the band to make contacts with no problems.

At no stage did I adjust the slugs in the PA and VFO coils.
If you use the method I have just described, you could
adjust the slug in the PA coil to make the PA track the
VFO. Follow the instructions in the manual for that.

By all means get your figures and do the calcs, but sooner
or later you'll have to use the empirical method. Hope this
helped.

73 de Neil ZL1ANM