Drive level


Colin Ranson
 

Morning all,

 

Thanks for all your suggestions reference 432MHz drive level into my 13/9cm SG-Lab transverters using the available low power from my home brew 28MHz transverter.

 

I did find a 10mW – 3w amplifier in my ‘RF modules’ box but I have now decided to go very simplistic and take up John Lemay’s (G4ZTR) idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.

 

This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.

 

Regards to all de G8LBS.

 

 

 

Sent from Mail for Windows 10

 


Gordon REASON <gordonj.reason@...>
 

yes , keep it simple , and let us know how you get on   !

On 06 April 2021 at 12:56 Colin Ranson <g8lbs@...> wrote:

Morning all,

 

Thanks for all your suggestions reference 432MHz drive level into my 13/9cm SG-Lab transverters using the available low power from my home brew 28MHz transverter.

 

I did find a 10mW – 3w amplifier in my ‘RF modules’ box but I have now decided to go very simplistic and take up John Lemay’s (G4ZTR) idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.

 

This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.

 

Regards to all de G8LBS.

 

 

 

Sent from Mail for Windows 10

 


 


 


Neil Smith G4DBN
 

...and if it works out nicely, can you take a pic and write a short note so the info can be added to the UKuG wiki on microwavers.org.

Neil G4DBN

On 6 Apr 2021 13:22, "Gordon REASON via groups.io" <gordonj.reason@...> wrote:

yes , keep it simple , and let us know how you get on   !

On 06 April 2021 at 12:56 Colin Ranson <g8lbs@...> wrote:

Morning all,

 

Thanks for all your suggestions reference 432MHz drive level into my 13/9cm SG-Lab transverters using the available low power from my home brew 28MHz transverter.

 

I did find a 10mW – 3w amplifier in my ‘RF modules’ box but I have now decided to go very simplistic and take up John Lemay’s (G4ZTR) idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.

 

This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.

 

Regards to all de G8LBS.

 

 

 

Sent from Mail for Windows 10

 


 


 



Colin Ranson
 

Will do !

 

 

Colin de G8LBS.

 

 

Sent from Mail for Windows 10

 

From: Neil Smith G4DBN
Sent: 06 April 2021 13:39
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Drive level

 

...and if it works out nicely, can you take a pic and write a short note so the info can be added to the UKuG wiki on microwavers.org.

 

Neil G4DBN

 

On 6 Apr 2021 13:22, "Gordon REASON via groups.io" <gordonj.reason@...> wrote:

yes , keep it simple , and let us know how you get on   !

On 06 April 2021 at 12:56 Colin Ranson <g8lbs@...> wrote:

Morning all,

 

Thanks for all your suggestions reference 432MHz drive level into my 13/9cm SG-Lab transverters using the available low power from my home brew 28MHz transverter.

 

I did find a 10mW – 3w amplifier in my ‘RF modules’ box but I have now decided to go very simplistic and take up John Lemay’s (G4ZTR) idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.

 

This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.

 

Regards to all de G8LBS.

 

 

 

Sent from Mail for Windows 10

 


 


 

 

 


militaryoperator
 

idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.
 
This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.
 
Regards to all de G8LBS.
 


Will not add a R mean you need more drive power. I thought you didn't have enough in the first place hence amp Colin?
I find I can't turn my 817 down low enough, bottoms out at about 250mw but seems ok on the 23, 13 and 9 SGL I use. 

Ben 
G4BXD


Neil Smith G4DBN
 

The usual trick, as John mentioned, is to solder a lower-value resistor on top of the existing one that is in series with the variable pot.  Typically in a Kuhne or F6BVA there is a 56 or 68 ohm dummy load resistor across the IF transmit input, then a 470 ohm fixed resistor and a 100 ohm pot.  The wiper of the pot goes to the transmit port of the mixer.

Soldering a 100 ohm resistor on top of the 470 means you can get full output at about 20 mW input instead of 250-500 mW wiht the pot at max gain.

This is the 100 ohm 0805 on top of the 470R

Neil G4DBN

On 06/04/2021 16:17, militaryoperator via groups.io wrote:
idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.
 
This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.
 
Regards to all de G8LBS.
 


Will not add a R mean you need more drive power. I thought you didn't have enough in the first place hence amp Colin?
I find I can't turn my 817 down low enough, bottoms out at about 250mw but seems ok on the 23, 13 and 9 SGL I use. 

Ben 
G4BXD
_.


SAM JEWELL
 

Works well with the 50mW from the Iceni 70cm transverter....

73 de Sam, G4DDK



On 6 Apr 2021, at 16:44, Neil Smith G4DBN <neil@...> wrote:



The usual trick, as John mentioned, is to solder a lower-value resistor on top of the existing one that is in series with the variable pot.  Typically in a Kuhne or F6BVA there is a 56 or 68 ohm dummy load resistor across the IF transmit input, then a 470 ohm fixed resistor and a 100 ohm pot.  The wiper of the pot goes to the transmit port of the mixer.

Soldering a 100 ohm resistor on top of the 470 means you can get full output at about 20 mW input instead of 250-500 mW wiht the pot at max gain.

<ejljehaocjblomle.png>

This is the 100 ohm 0805 on top of the 470R

<dimhnalbkmcmjneb.png>

Neil G4DBN

On 06/04/2021 16:17, militaryoperator via groups.io wrote:
idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.
 
This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.
 
Regards to all de G8LBS.
 


Will not add a R mean you need more drive power. I thought you didn't have enough in the first place hence amp Colin?
I find I can't turn my 817 down low enough, bottoms out at about 250mw but seems ok on the 23, 13 and 9 SGL I use. 

Ben 
G4BXD
_.


ian hope (2E0IJH)
 

Depends where you put the resistor in the chain, whether you make the inbuilt attenator greater or smaller.
 
Ian
M5IJH

 
 
Sent: Tuesday, April 06, 2021 at 4:17 PM
From: "militaryoperator via groups.io" <Military1944@...>
To: "UKMicrowaves@groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Drive level
 
 
 
 
idea of a simple resistor addition to the attenuator chain.     Many thanks for that idea John.
 
This means I can knock back the 250mW I presently have and also add a TOKO filter for better spectral purity.
 
Regards to all de G8LBS.
 
 
 
Will not add a R mean you need more drive power. I thought you didn't have enough in the first place hence amp Colin?
I find I can't turn my 817 down low enough, bottoms out at about 250mw but seems ok on the 23, 13 and 9 SGL I use. 
 
Ben 
G4BXD
 
 
 
 
 


militaryoperator
 

Depends where you put the resistor in the chain, whether you make the inbuilt attenator greater or smaller.
 


Yes, guess its a matter of adding a resistor or actually, as in this case, reducing a resistor. 
All in the way its phrased obviously. English, a great language. 

BN