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set19 mk3 mode switch setting


carlos
 

hi, 
for receiving cw is the setting to r/t mode correct?  
i have a loud cw tone on the cw setting, maybe thats normal
then there is also mcw , is this for cw receive as wellthanks carlos


Chris_Suslowicz
 

Carlos wrote:

hi,
for receiving cw is the setting to r/t mode correct?
Er, no. CW setting is for CW (and enables the BFO when on receive), you can adjust the note of the incoming signal with the "Het Tone" control that shifts the BFO frequency slightly.

i have a loud cw tone on the cw setting, maybe thats normal
If you have a Mk.3 set and it has a tone with no signal, the audio output stage is probably oscillating. This is a known problem if you do not have enough load on the AF output (a single headset), and there was an official modification to prevent it. (Plug another headset in if you have one.)

then there is also mcw , is this for cw receive as well
CW is Continuous Wave - it just sends the RF carrier when the key is pressed.

MCW is Modulated Carrier Wave - the RF carrier is sent continuously on transmit but is modulated with a tone when the key is pressed.

R/T is Radio Telephony - the microphone modulates the RF carrier on transmit.

thanks carlos
You're welcome.

Best regards,
Chris. (G8KGS)


carlos
 

hi chris, thanks for your info, thats clear now
so i suspect the headplhone connection sits in the pye 12pin output connector under the power input connector,
my mk3 has a homemade powersuply(not by me) who delivers all voltages needed for rx and tx,
het has even an audiostage build in with a speaker,volume control, bass and trebble,
the r/t mode is working and the rf power output is 6 watts cw,
so if i connect a headphone to the headphone output pins for load can be the solution for oscillating in cw mode,
wil try to figure out wich pins are for the headphones if tey are in the 12 pins outor
carlos


Chris_Suslowicz
 

Carlos wrote:

hi chris, thanks for your info, thats clear now
so i suspect the headplhone connection sits in the pye 12pin output connector under the power input connector,
my mk3 has a homemade powersuply(not by me) who delivers all voltages needed for rx and tx,
het has even an audiostage build in with a speaker,volume control, bass and trebble,
the r/t mode is working and the rf power output is 6 watts cw,
so if i connect a headphone to the headphone output pins for load can be the solution for oscillating in cw mode,
wil try to figure out wich pins are for the headphones if tey are in the 12 pins outor
Because your set has been heavily modified, that may not be the problem.

Check that you haven't left the 'Net' switch in the 'on' position on R/T, that will cause a continuous tone if there's a signal present.

If you have a tone present on CW with no aerial connected then there is probably a fault inside the set (something is oscillating that should not be) and you need to track that down.

Best regards,
Chris.


OldBlueBear-G4JHT-Dave
 

Hi,
I question if:

"MCW is Modulated Carrier Wave - the RF carrier is sent continuously on transmit but is
modulated with a tone when the key is pressed."
is correct.
Perhaps the WS19 being of 1938 vintage (?) is different.

But MCW (A2) in my book (ITU RR) is a carrier modulated with tone (around 800 cycles) to around 98% depth and the whole lot keyed on/off for Morse signaling.

This is what was used on the 500 Kc/c, 600 meter, MF Marine Band.
Originally MCW (ICW) was intended for a replacement for the "sonic-train" of the spark rate produced in the operators headset as the result of detecting Spark (class B) waves.

Like Spark, a MCW signal has a "punch" that rides through both all types of QRM and QRN - that is why it is still used.

I am licensed to use it here if I wish at EI0DB except on MF/LF (below 160 meters) where it might be mistaken for a survival craft beacon signal.

73s,
OldBlueBear-g4jht-dave


carlos
 

hi, chris 
it seems the twin peak filter crcuit is oscillating, 
when i turn the volume knob on max and the load is a headphone of 4000 ohms  on the 12 pins pye connector the oscllation stops,
so i kan hear cw signals and peak the tone with the het tone pot, audio is  verry bad of course, i believe the load most be 600 ohms for a headphone or speaker
i dont now if this a known issue or mods available
carlos on6cn


Jacques_VE2JFE
 

Hello Carlos,

 

The headphones used with the WS #19 installations have an impedance of 100 ohms (two 50 ohms earpieces in series).

The A set output transformer, T2A, was designed for a 25 ohms secondary load to feed up to four headsets at the same time, and then reflects 5000 ohms to the V3A plate winding.

With 4000 ohms or even 600 ohms, you are still way too high…

 

You are right when you suspect the twin-T filter.

It’s role is to provide feedback around the V3A stage in CW mode, attenuating all audio frequencies except for a range around 640 Hz.

This twin-T characteristics had been voluntarily “degraded” to control the filter band pass, but if the resistors used within goes high in value, (what is surely what happened if they are still the original ones there) the whole stage can oscillate at 640 Hz or about…

R48A can cause this, particularly…

The twin-T filter components are assembled to a vertical phenolic board near the 807 valve.

 

This type of problem does not happen in the Canadian sets (no twin-T filter).

 

73, Jacques, VE2JFE


carlos
 

thanks jacques for the valuable info,we gone dig in to it later,
first the trio ts510 now.

Op wo 25 nov. 2020 om 17:32 schreef Jacques_VE2JFE <jacques.f@videotron.ca>:


Hello Carlos,



The headphones used with the WS #19 installations have an impedance of 100 ohms (two 50 ohms earpieces in series).

The A set output transformer, T2A, was designed for a 25 ohms secondary load to feed up to four headsets at the same time, and then reflects 5000 ohms to the V3A plate winding.

With 4000 ohms or even 600 ohms, you are still way too high…



You are right when you suspect the twin-T filter.

It’s role is to provide feedback around the V3A stage in CW mode, attenuating all audio frequencies except for a range around 640 Hz.

This twin-T characteristics had been voluntarily “degraded” to control the filter band pass, but if the resistors used within goes high in value, (what is surely what happened if they are still the original ones there) the whole stage can oscillate at 640 Hz or about…

R48A can cause this, particularly…

The twin-T filter components are assembled to a vertical phenolic board near the 807 valve.



This type of problem does not happen in the Canadian sets (no twin-T filter).



73, Jacques, VE2JFE

--
mvg carlos popelier
regards carlos popelier