wehrmacht awards


Go Back   Wehrmacht-Awards.com Militaria Forums > Wehrmacht Uniforms and Equipment > Communications Equipment

Communications Equipment Radio, telephony and radar equipment

Reply
 
Thread Tools Display Modes

80W.S. antenna impedance.
Old 10-26-2016, 05:48 AM   #1
Guglielmo Terra
New Member
 
Guglielmo Terra is offline
Join Date: Dec 2014
Location: Italy
Posts: 10
Default 80W.S. antenna impedance.

I have a transmitter 80W.S. and I was interested to know its characteristic impedance. In fact, the power can be read on thermo Ammeter antenna with the formula W = R * I squared. Example W = 60 * (0.8 * 0.8) = 38.4 watts.
But "R" you must know.
By some threads that I read would seem 60 or 70 ohms ...
Regards
Riccardo.
  Reply With Quote

Old 10-26-2016, 11:35 AM   #2
Funksammler
Member
 
Funksammler is online now
Join Date: Jan 2009
Location: Normandy
Posts: 2,965
Default

The Germans rarely were able to operate these sets with a properly matched antenna, so I guess your question is a bit like "How long is a piece of string".

They used different antenna's with the 80 W.S.; especially on vehicles the antenna was far from effective. One of the antenna types was the Sternantenne D, a 1.4 meter rod with a capacitive top, this required an addtional lenghtening coil. Not a clue what the impedance of this setup would be (probably pretty low with a significant phase shift), the actually antenna (the 1.4 meter rod) would radiate only a fraction of the power (some sources claim about 2%).

regards,

Funksammler
  Reply With Quote

Old 10-26-2016, 03:43 PM   #3
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

FS, we both have dummy loads. Can they be used to answer this question?
  Reply With Quote

Old 10-26-2016, 04:17 PM   #4
Funksammler
Member
 
Funksammler is online now
Join Date: Jan 2009
Location: Normandy
Posts: 2,965
Default

Quote:
Originally Posted by Yuri D. View Post
FS, we both have dummy loads. Can they be used to answer this question?
Approximately I guess, although the 80 W.S. dummyload is not quite an artificial antenna. I have to check, but I think it just consists of 3 incandescent lamps in parallel so will mainly have a resistive value, it does not take any phase shift into consideration.

regards,

Funksammler
  Reply With Quote

Old 10-26-2016, 10:47 PM   #5
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

Quote:
Originally Posted by Funksammler View Post
Approximately I guess, although the 80 W.S. dummyload is not quite an artificial antenna. I have to check, but I think it just consists of 3 incandescent lamps in parallel so will mainly have a resistive value, it does not take any phase shift into consideration.

regards,

Funksammler

Right. Doesn't take inductive or capacitive load into account also.
  Reply With Quote

Old 10-26-2016, 11:06 PM   #6
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

Quote:
Originally Posted by Funksammler View Post
Approximately I guess, although the 80 W.S. dummyload is not quite an artificial antenna. I have to check, but I think it just consists of 3 incandescent lamps in parallel so will mainly have a resistive value, it does not take any phase shift into consideration.

regards,

Funksammler
But it is well known that German mobile transmitters in WWII were very inefficient. Perhaps 4-5% of transmitted power left the antenna with some of them. The post-war SEM-25 system had better efficiency of about 11-13%.
  Reply With Quote

Old 10-27-2016, 08:58 AM   #7
Guglielmo Terra
New Member
 
Guglielmo Terra is offline
Join Date: Dec 2014
Location: Italy
Posts: 10
Default

Thanks for all the answers.
I ask the question in other terms.
We will never know how many watts is the value that we read on the ammeter antenna?
Tanks
  Reply With Quote

Old 10-27-2016, 11:10 AM   #8
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

Quote:
Originally Posted by Guglielmo Terra View Post
Thanks for all the answers.
I ask the question in other terms.
We will never know how many watts is the value that we read on the ammeter antenna?
Tanks
Efficiency = output/input

So it's volts*amps on the antenna divided by 80 Watts. Make sure you're power input is 12 volts filament, and 800 volts for anode. If you have the original impedance matching boxes and correct star antenna, connect it all together and tune the output inductor for max antenna current on the meter. You can also get a variable series inductor (antenna tuner) and tune it to get the maximum SWR possible. This would most likely improve the efficiency of the transmitter, but would not simulate real conditions in a command tank or armored transport.
  Reply With Quote

Old 10-27-2016, 11:11 AM   #9
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

Quote:
Originally Posted by Guglielmo Terra View Post
Thanks for all the answers.
I ask the question in other terms.
We will never know how many watts is the value that we read on the ammeter antenna?
Tanks
Do you have the Antennenspule 30/80?
  Reply With Quote

Old 10-28-2016, 05:44 PM   #10
Funksammler
Member
 
Funksammler is online now
Join Date: Jan 2009
Location: Normandy
Posts: 2,965
Default

Quote:
Originally Posted by Guglielmo Terra View Post
Thanks for all the answers.
I ask the question in other terms.
We will never know how many watts is the value that we read on the ammeter antenna?
Tanks
It will probably not with a real antenna as the ampmeter will give a (rough) indication of the antenna current without regard of the phase shift, in the worse case you could have a 90 degree shift, maximum current and no actual power output. With a purely resistive load (such as the dummy load) you could work it out the power from the amp meter reading. You would need a 5 Ohm dummyload to get about full scale on the amp meter on the 30 and 80 Watt transmitters (2.5A on the 30 W.S.a and 4A on the 80 W.S.), this would be carrier + full modulation.

regards,

Funksammler
  Reply With Quote

Old 10-28-2016, 05:56 PM   #11
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

Quote:
Originally Posted by Funksammler View Post
It will probably not with a real antenna as the ampmeter will give a (rough) indication of the antenna current without regard of the phase shift, in the worse case you could have a 90 degree shift, maximum current and no actual power output. With a purely resistive load (such as the dummy load) you could work it out the power from the amp meter reading. You would need a 5 Ohm dummyload to get about full scale on the amp meter on the 30 and 80 Watt transmitters (2.5A on the 30 W.S.a and 4A on the 80 W.S.), this would be carrier + full modulation.

regards,

Funksammler
Is the phase shift part of the design, or an artifact of a malfunctioning transmitter?
  Reply With Quote

Old 10-29-2016, 02:46 AM   #12
Funksammler
Member
 
Funksammler is online now
Join Date: Jan 2009
Location: Normandy
Posts: 2,965
Default

I think the phase shift is inherent in the design of the antennas and the antenna matching circuitry of long/medium wave transmitters. The losses in the output circuit and antenna are mainly caused by the imaginary part of the power. In a system where the antenna is so much shorter as the wavelength the antenna has to be artificially "lengthened" by coils and capacitors, creating extra phase shifts. (In VHf systems where the antenna can be more easily matched to a quarter wavelength the losses occur more in the transmission line between the transmitter and antenna).

regards,

Funksammler
  Reply With Quote

Old 10-29-2016, 12:11 PM   #13
Guglielmo Terra
New Member
 
Guglielmo Terra is offline
Join Date: Dec 2014
Location: Italy
Posts: 10
Default

Hello, in response to Yuri, I do not have the Antennenspule 30/80.
A dummy load 5 ohms may already be a good indication.
In my case with dummy load 50 ohms, after having accorded, get on the wattmeter about 60 Watts, but the antenna ammeter remains at about 0.5 amps.
Regards, Riccardo.
  Reply With Quote

KA80a
Old 11-02-2016, 12:00 PM   #14
ARYEH
Member
 
ARYEH is offline
Join Date: Nov 2008
Location: Israel
Posts: 151
Default KA80a

Quote:
Originally Posted by Funksammler View Post
Approximately I guess, although the 80 W.S. dummyload is not quite an artificial antenna. I have to check, but I think it just consists of 3 incandescent lamps in parallel so will mainly have a resistive value, it does not take any phase shift into consideration.

regards,

Funksammler
Hi:
The KA80a for the 80WS is described in https://www.nonstopsystems.com/DL9HZH/KunstAntennen.pdf together with calculations.

Cheers
ARYEH
  Reply With Quote

Old 11-03-2016, 01:12 PM   #15
Yuri D.
Association Member
 
Yuri D.'s Avatar
 
Yuri D. is offline
Join Date: Apr 2001
Location: Western Hemisphere
Posts: 6,174
Default

Quote:
Originally Posted by ARYEH View Post
Hi:
The KA80a for the 80WS is described in https://www.nonstopsystems.com/DL9HZH/KunstAntennen.pdf together with calculations.

Cheers
ARYEH

You are correct Aryeh. That doc has all the values and math for that dummy load. It would be safe to say that this dummy load can be used to test and tune the transmitter to 1940s field standards. Anything better than that can be achieved with a modern high quality antenna tuner.
  Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump






vBulletin skins developed by: eXtremepixels
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright Wehrmacht-Awards.com