I'm resurrecting an HW-16 that I picked up at a swap
meet last month. I've gotten it working, aligned it
per the manual, and the tubes are all good. Output
power is about 45 Watts on 40m and 80m, and about 30
Watts on 15m, about what I expected. I do have some
questions for you HW-16 experts to ponder:

(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?).

(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.

(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?

(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.

Your thoughts on any of this would be appreciated.

Thanks and 73,
Dean K5DH

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 filter
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 check
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 freq.
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 that
don't know no better. Chirp is caused by B+ instability (I.E. Voltage drops
when hit the key - No Volt regulation) sooooo look at the skezmatic - see
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 coming
from C4/R3/R4 to Point B buss. Tie this wire to Pont A in the power supply.
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 cleanly
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 changes
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 regulator
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 tube
so its cold - solder a wire to input pin and output pin and stick the whole
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 OFF
the receiver - R49 10K - try a 10k trim pot and adjust level to your liking.

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 have to
key up the transmitter to find out where the heck you are on the receiver
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 DRIVER/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 "trying to
find yourself"

RF Power - Pretty crappy power control. You adjust the RF power by varying
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. Now
you can go from full power down to about 2 or 3 watts. If you increase R14
you can get it down into the Milliwatt range and still go up to full power
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 variable
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 "cranking"
to move around from end to end - but it's more accurately set and is more
frequency stable.

Thanks and 73, - Biz WDØHCO

Dean K5DH

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