[Heathkit] HW-16 L-9 Value

[Mark K3MSB]

Hi Miles.

Well, success!   In a round about way.

I adjusted L8 then followed the rest of the procedures for 15, 40 and 80M.
   I got a nice 20W out on 15M and 40 to 50W on the other bands.

But the tube shields were off.

I put them on an no output on 15M.    So,  with the tube shields back on I
followed the adjustment procedure again.    The adjustments were different
with the shields on.  Again,  20W out on 15M  and 40 to 50 on 40 and 80.

I then put the metal bottom plate on the radio and the power on 40M fell
off to only 20W.   At that point I readjusted all three bands looking at
the power output.    Go back to the 20W on 15M and 40 to 50 on the other
bands.   With the tube shields on.......

Works well with Crystals or VFO!!

73 Mark K3MSB

On Sat, Apr 11, 2020 at 1:32 PM <k2cby at optonline.net> wrote:

> Mark,
>
> I strongly suspect that you are getting output using the VFO with both tube
> shields off because the driver is going into self-oscillation at some
> unknown frequency independent of the VFO.
>
> I assume you've measured the key-down dc voltages on V7, V8 & V9 with a 40M
> crystal plugged in and that they are within 10 or 15% of what the schematic
> shows. If not, you should do so and troubleshoot as necessary.
>
> Have you peaked L8 per the left-hand column on page 41 of the instructions?
> It should resonate somewhere in the 40 Meter band.
>
> One thing in the schematic struck me as strange. The VFO input socket makes
> a dc connection to the control grid of V7. If there is dc (or a ground
> return) at the output of whatever FVO you are using (or if any coupling
> capacitor is leaky or shorted) it is going to kill the V7 grid bias. Along
> the same line, you don't want to use a long run of coax from the VFO to the
> xmtr because of attenuation.
>
> I assume both sets of measurements shown on your most recent post were made
> with all tube shields in place. I also assume you used a 10X probe so the
> scope isn't loading the measurements and the scope and the probe have a
> more
> or less flat response to at least 21 MHz.
>
> Last - but hardly least - I certainly assume you've replaced both 6CL6's
> with known good tubes. (By the way, the best one should go in V8, which
> does
> the "heavy lifting" as a tripler.)
>
> That's about all I can think of at the moment.
> We've got a mandate to "shelter in place" so I'm lurking on the internet a
> lot more than usual.
>
> 73, Miles
>
>
>
> Miles B. Anderson, K2CBY
> 16 Round Pond Lane
> Sag Harbor, New York 11963-3821
> Phone: (631) 725-4400
> FAX: (631) 725-2223
>
> e-mail: k2cby at optimum.net
>
>
>
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