[Premium-Rx] Racal RA1778 alignment instructions error

[John Nelson]

Having recently had occasion to refurbish a Racal RA1778, it seemed worth
mentioning that there is an error in Steps 19-24 of the PS337 HF loop board
alignment procedure (Pages 23-10 and 23-11 of the manual). This seems to be
perpetuated from the RA1772 manual, which contains the same error. 

The inductors associated with each of the three VCOs are as follows: 
L4	0-7MHz
L5	8-17MHz
L6	18-29MHz
In the alignment instructions the manual inverts L4 and L6. It states that
L5 should be adjusted with Channel 5 (17.999) set, which is correct, but L6
should be adjusted with Channel 4 (7.999) set. This should be Channel 3
(29.999). The manual also does not specify the required channel setting for
L4, which should presumably be Channel 4 (7.999). 

The correct adjustment procedure is therefore as follows: 

Adjust L4 with Channel 4 (7.999) set. 
Adjust L5 with Channel 5 (17.999) set. 
Adjust L6 with Channel 3 (29.999)set. 

There is an undocumented test point located between L5 and L6 which is the
common varactor line connecting L21, L22 and L23. This can be used as the
measurement point. Each VCO inductor should be set to give 14.00V at this
point when the appropriate channel is selected as above. 

Racal manuals often seem to contain errors of this sort but this one caused
some head-scratching.  

73 John
GW4FRX