[Heathkit] Attn: SB-401 Gurus

[Michael Waldrop]

Hi Ed,

Another method involves using a separate receiver that tunes
8.6Mhz. A modern day all band HF transceiver will do nicely.
You will need to use a short piece of wire as an antenna, 
connected to the separate receiver's antenna SO-239 
then place the other end of the wire close to or next
to the SB-401's heterodyne mixer. The following method
does not require the RF probe and a VTVM.

Perform the steps outlined in the manual up to the point of
actually adjusting the 8.6Mhz trap capacitor C-303. 

Now, tune the separate receiver until you find the SB-401's
8.6Mhz signal. To be sure you have the right signal, switch
the SB-401 in and out of SPOT. If you are sure you have the
right signal, adjust C-303 for a minimum S meter reading on
the separate receiver. That's all there is to it.

If the 8.6Mhz signal is too strong, move the short antenna wire away
from the SB-401 until the signal is between S7 and S9 then
adjust C-303 for minimum S meter reading on the separate
receiver.

You may not be able to completely eliminate the 8.6Mhz signal.
The key is to reduce the level of the 8.6Mhz signal to an acceptable
level for spurious emissions at 8.6Mhz as defined by the FCC rules.

73's
Mike
W5RKL


Edward B Richards <zuu6k at juno.com> wrote: Hi guys;

I am realigning a SB-401 and all went well until I tried to tune the 6.8
mc trap. I followed the book exactly but adjusting the capacitor (C303)
does nothing to the RF voltage on the final grids. I replaced the
capacitor with no improvement. I am about to order a new choke (RFC2)
although the original looks good. I thought I would seek advice first.
Anyone have this experience? Any suggestions? Thank you.

73 Ed K6UUZ
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