[Heathkit] Heathkit HW-16 chirp/mods

[Tom NØJMY - AAR7FV]

Jerry, I've never found the HW-16 to be more stable with the HG-10 than 
with xtals.  It was usually the other way around for me, but I wouldn't 
rule it out under all circumstances.

The most effective mod I have made to the HW-16 to reduce or eliminate 
chirp is to install a
mica capacitor directly from the screen connection on the oscillator 
tube (6CL6) to the nearest ground point.  Credit for this mod goes to 
Ken Gordon, W7EKB.  You will probably have to experiment a little bit 
with the value of the capacitor.  Mine works best at 100 pf.  Ken got 
his best results at 220 pf.  The higher you go, the greater the chance 
of your crystal not starting.  Obviously it pays to use the most active 
crystals you can find.

There's also a simple no holes mod to I did to mine that allows the 
oscillator to run all the time during transmit, and makes the QSK 
optional.  Credit for this one belongs to Steve Johnston, WD8DAS.  Here 
is Steve's instructions, pretty well verbatim:

"Remove the upper crystal socket and use the two holes for a mini DPDT 
switch and an LED in chrome holder (both from Radio Shack). No drilling 
needed and it would be simple to put the crystal socket back later.

"The pole and one throw of side of the DPDT switch is used to interrupt 
the connection of the 47k oscillator grid-blocking resistor R1 to the 
terminal strip where it gets the negative voltage (keying line).  In 
other words, detach R1 where it attaches to the terminal strip (the 
other end or R1 is attached to the oscillator tube) Run a wire from the 
detached end of R1 to one of the poles of the DPDT switch. Then run 
another wire from the terminal where R1 was previously connected  up to 
one of the throw terminals for that same pole on the switch.

"Then find the white RX muting wire that connects "point Y" on the 
receiver board to pin 8 of the rear-panel octal socket. Remove it from 
the octal socket and use it to connect point Y to the same end of R1 
where you connected the switch, i.e. the end away from the tube.

"Switch open is the "transmit" position, switch closed is the "break-in" 
and "receive" position.

"The other half of the DPDT switch is used to turn on the LED so you get 
a red light when in manual transmit mode. Grab the 6.3 VAC from the 
nearby meter pilot light, run it through a 1N914 diode and 1k resistor 
to turn it into current-limited DC for the LED (or I guess you could use 
a small 6.3 v lamp in a miniature holder)."

I did mine slightly different because I use both types of crystals. I 
removed the wires for the meter switch and wired my meter permanently to 
read plate current  For relative power, I stuck a neon bulb behind the 
meter (can't remember off-hand where I picked the RF off of to light 
it).  Anyway, it now tunes like a 2-NT, meter dips, neon glows.

Then I just used one side of the old DPDT meter switch to do the 
switching work that Steve describes.  Makes a decent T/R switch.  Of 
course, if you're not into QSK at all, you can use the other half of the 
switch to kill your key during receive.

When I was a novice, the HW-16 reigned supreme and they didn't seem to 
be chirpy in the sense we think of today.  That is, what we call a 
chirp, is really a "yoop".  You could almost alway tell a HW-16 back 
then, thought because it's note sounded like someone was putting a "t" 
on the front of each element -- "too-to-too-toot  too-too-to tooo".  Too 
this day, I don't know if it was a very fast chirp, or a key click.  I 
have presumed the former.

BTW, if you can get your hands on any pots with push-pull switch shafts, 
grab 'em.   The make great no-holes controls in place of the standard RF 
gain and PWR level controls.  I use mine to kick in a simple 80 Hz. 
audio filter, and to switch the final and the meter to Ade Weiss's 400 
mW QRP mod.

There are other things you can try, such as recapping the P/S with 
higher value caps (80's and/or 100's) for better regulation.  I've never 
done that expressly for the purpose of getting rid of chirp, but some 
guys recommend it.  You can also make an old power transistor work like 
a zener to regulate oscillator voltage.  I haven't done that yet, either

I'm sure there are lots of others. And I'd like to hear anyone elses 
mods, as I have recently taken up HTML and CSS and I might make a HW-16 
website.

73,
Tom NØJMY


----- Original Message ----- 
From: "NR5A" <nr5a at rap.midco.net>
To: <heathkit at mailman.qth.net>
Sent: Friday, February 25, 2005 12:46 PM
Subject: [Heathkit] Heathkit HW-16 chirp/mods


> Is there a webpage, or details somewhere that has simple mods for a 
> HW-16 to
> get rid of chirp?? I get chirp bad enough when using FT-243 crystals 
> on 40m
> I get OO reports. hi hi  I've heard it won't chirp using the HG-10 
> VFO, is
> this true and why???
>
> Jerry - NR5A
>
>
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