Thanks Biz! I was hoping you'd chime in, since you're the
resident HW-16 "guru" around these parts! I've printed off
your msg text and will begin experimenting on my rig as soon
as I can. It's too scruffy to "restore", but definitely a
good candidate for playing around with.

73,
Dean K5DH


In article , says...

Glad to help Dean-O....

(1) The receiver is the most sensitive in the middle
of the VFO range, and the sensitivity falls off a lot
toward the ends of the VFO travel, regardless of where
I have it tuned when I do the alignment. All of the
alignment adjustments work like the manual says they
should. Any ideas on what might be wrong? I've owned
HW-16s in the past and I don't recall this being the
case with them (poor memory?).

No your memory is correct - I am making the assumption you have noticed
this
on all bands. More than likely one of the 3595 khz xtals in the xtal fil
ter
has changed activity level - let's try bypassing it - run a wire between
C65
and the point at C66/R39. You should get a much wider IF sig now. Now ch
eck
your sensitivity at both ends of the dial.

(2) How would I change the audio frequency of the neon
reflex sidetone oscillator? 1 KHz is too high for me.
I'd prefer something around 750 Hz or so.

You can try changing R64 1.5M to 5M. Remember T=RC so a lower resistance
value should lower the osc freq. You might want to put a pot to adjust f
req.
To decrease volume increase resistance R63 - try a 1K to start.

(3) The transmitter is chirpy. I know, all HW-16's are
chirpy. I found a mod on line which suggests adding a
220 pF mica cap from the screen grid of the oscillator
tube to ground to combat the chirp. I tried it, and I
find that if I add capacitance there, the oscillator
gets extremely sluggish. I tried various values from
100 pF to about 250 pF. Any thoughts on this?

Yea this mod has been a around a long time. It's really for lazy hams th
at
don't know no better. Chirp is caused by B+ instability (I.E. Voltage dr
ops
when hit the key - No Volt regulation) sooooo look at the skezmatic - se
e
how the ENTIRE transmitter's B+ is tied to Point B (310 VDC). Whose
brilliant idea was this ?!?!?!

First thing to do is ISOLATE the oscillator V7. Disconnect the wire comi
ng
from C4/R3/R4 to Point B buss. Tie this wire to Pont A in the power supp
ly.
Skezzzzmatic shows that this is the B+ supply for the receiver. It only
provides only +175 VDC but it's more than enough for V7 to oscillate cle
anly
at only a slightly reduced level.

The Point A voltage is actually pretty stable when transmitting. Because
the
700 VDC voltage drop from R207/R206 and R203 to 175 VDC that voltage cha
nges
very little at this point.

Doing this mod will make the HW-16 sound like a Kenwood/Yaesu/Icom on CW
.

If you want to make it sound like a Ten Tec - place an OB2 volt regulato
r
inline with the B+ power wire. OB2 will take the voltage down to 125 vdc
but
it will be rock solid. V7 Oscillator will be a pure T9er. OB2 is a gas t
ube
so its cold - solder a wire to input pin and output pin and stick the wh
ole
thing inside a shrink tube. you can then place it underneath the chassis
...
or you could punch a hole and put a tube socket near V7.

(4) How can I increase the level of the spotting signal
that's heard in the receiver? If I could bring it up
high enough, I'd consider disabling the harsh sidetone
oscillator and just listen to the transmitted signal as
my sidetone, which is what I do with my homebrew tube
transmitters and Drake 2B receiver.

Side tone level comes from Bias Switch Q1 which does not quite switch OF
F
the receiver - R49 10K - try a 10k trim pot and adjust level to your lik
ing.

Your thoughts on any of this would be appreciated.

No thoughts - I've done these mods.... and have many more...

Spot Button - One thing I REALLY hate about the '16 is the fact your hav
e to
key up the transmitter to find out where the heck you are on the receive
r
dial. This is what is called QRM - which in CW stands for interference -
This reflects on a really **** poor HFE (Human Factors Engineering)
sooooo...

How about mounting a DPDT push button switch. One Pole would be used to
key
up the transmitter from the key jack. The other Pole would be connected
between C7 and PIN 9 on the V8 DRIVER. Now when you push the SPOT switch
-
it keys up the transmitter and also disconnects the input into the DRIVE
R/PA
so it doesn't go out over the air. You will find that lil oscillator is
plenty strong Side Tone and the rest of us don't have to hear you "tryin
g to
find yourself"

RF Power - Pretty crappy power control. You adjust the RF power by varyi
ng
the B+ into the V9 PA. Pretty damn STOOOPID design - Here is a better
way....

Disconnect and tie the wires from points 2 and 3 of the R13 Power Level
POT
point together. Now the V9 PA will be going at FULL BLAST at all times.

Now disconnect the wire from B buss to R6. Wire B buss to Point 3 of the
Power Level Pot. Shot a wire from Point 2 of the power level pot to R6.

You have just duplicated the same circuit but attached it to the IPA. No
w
you can go from full power down to about 2 or 3 watts. If you increase R
14
you can get it down into the Milliwatt range and still go up to full pow
er
with a twist of a knob. YEEEHAAA - HW-16 makes a great QRP rig!

Have fun and don't worry about screwing it - wadda going to loose $20-50
???

Got a HG-10B VFO ?? Remove one rear plate on STATOR (Fixed) of the varia
ble
cap. A slight trim adjustment and your HG-10B Now has a expanded CW band
.
Yes you loose the top end of the ham band and you have to do more "crank
ing"
to move around from end to end - but it's more accurately set and is mor
e
frequency stable.

Thanks and 73, - Biz WDØHCO

Dean K5DH