Mohawk Questions

[Michael Waldrop W5RKL]

Mohawk:

I like my Mohawk even though it has design flaws, specifically the AGC
and drift, especially on 20 and above. Electric Radio carried a series of
articles by Thomas Bonomo, K6AD, that contained numerous modifications to
improve the Mohawk's performance. The Electric Radio articles are available
from Electric Radio magazine for a very small fee. My Mohawk is stock and
works just fine for me. Since I only use it on 75/40 meter AM, I am not
concerned about the short comings it has.

If hum is heard regardless of the amount, the power supply metal caps is
going bad.

The notch should greatly reduce interference at the "mid" point on the null
control. This is set inside the Mohawk's notch filte's adjustment. The
amount of notch is also set at the front panel as well as on the inside of
the Mohawk.

The S meter is adjusted with the antenna removed and the RF and IF gain
controls set to minimum. Set the control for zero on the meter. The
meter is not accurate. I don't relay on the meter, I simply
make sure it's set to zero.

Clean all of the switches and align the dial so it sit in the middle of the
window, not up or down. This is accomplished by adjusting the bandswitch
cord adjustment. It's easy.

Lightly lubricate the dial wheels and spring with WD-40 using a cotton
swab. It makes the dial rotate much easier.

Pay close attention to the selectivity control linkage. They do become
loose so tighten them as needed.

The Mohawk will work on 24Mhz without any modifications. The Mohawk
has 6 and 2 meter dial markings. Turning the bandswitch to 6 or 2 meters
puts the Mohawk on 24Mhz, no mods required.

If you are using a Dow Key relay with your Mohawk, pay close attention
to the relay. I burnt out an 80 meter cap in the antenna circuit because
the Dow Key relay was bad. I keyed my Apache and it fed 120 watts
straight into the front end. Needless to say, replacing the cap fixed
the problem. Rewinding the antenna coils is another story. I've done
it before, on a Hallicrafters SX-111; it's not fun and quite difficult.
I no longer use Dow Key relays. I build my own T/R relay box using
120VAC DPDT relays, 3 SO-239 connectors and the innner wire of RG-8x.
That works much better.


Marauder:

I like my Marauder. It does an excellent job on CW and sideband. If used
on AM, stick to the 100 ma plate current otherwise you will be replacing
the power transformer and final tubes plus possibly a few other components
if you run it any higher.

If the power supply caps are original, replace them. The Marauder was
designed and marketed in the very early 60's. That is 45 plus years ago
and I am sure they are leaky.

The final cooling. If it runs slow, clean it. If cleaning does not improve
the fan's speed, replace it. I replaced mine with a 120VAC muffin fan. I
had to replace the top cover with perforated aluminum and mount the
fan directly to the aluminum cover. It works very well and keeps the
finals quite cool.

Speaking of finals, do not use 6146B or any "B" related version of
6146 final tube. The Marauder was designed around the plain Jane
6146 or the 6146A. You may get lots of output using the "B" version.
However, using the "B" version can possbily burn up the final neutralizing
components. Have a look at Glenn Zook's "The 6146 Family of Tubes" for
further details.

Peform the alignment outlined in the manual paying close attention to
the 6 and 13Mhz traps. If these traps are not properly adjusted, the
Marauder will be transmitting spurious emissions on 6 or 13Mhz, depending
on what band you are operating on.

If the CW delay does not hold longer than a few seconds, that is caused
by the pot and fixed resistors. Either one or both have chanaged values.
I found the pot in my Marauder had "decreased" in value. To compensate
for this, without having to order a new pot, I simply increased the
fixed resistor which brought the delay up to where it should be.

All in all, the Mohawk and Marauder are good boatanchors. I use both of
mine quite often and enjoy them very much. Have fun and maybe I'll hear
you on the band with your Marauder.

73's
Mike
W5RKL

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