new builder

This forum is all about building and using World War II spy radio equipment, in particular the Whaddon MK-VII (Paraset). For other radios, separate forums can be set up - ask the Quartermaster.

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holowvan
Posts: 2
Joined: 22 Apr 2020, 09:28

new builder

Post by holowvan »

hi all im a new builder just starting to get some components together and my question is as follows
the reaction control has a 20K 0.5w variable pot should it be a single or multiple turn device
thanks in advance
martin
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Parasetguy
Beheerder
Posts: 52
Joined: 21 Aug 2018, 15:32
Location: The Netherlands, Velp
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Re: new builder

Post by Parasetguy »

Hi Martin

As far as I know, they had no multiturn pots during WW2. Anyway, a singleturn was used. Must be linear!
I have doubts if a multiturn would be convenience. But you can try, no harm done.

73 de Henk - Parasetguy
holowvan
Posts: 2
Joined: 22 Apr 2020, 09:28

Re: new builder

Post by holowvan »

thanks henk one more part found not doing too badly thanks single turn it is
73 martin
John 4EDX
Posts: 3
Joined: 04 Nov 2020, 07:03

Re: new builder

Post by John 4EDX »

Hello Martin,

I too am building a Paraset replica and I've got a 10-turn pot for the reaction control too. I have a single turn 22k pot but the bush is slightly larger in diameter than the hole in the panel and I don't want to enlarge it.

I had the receiver built on a temporary chassis and I found that the first stage went into and out of oscillation very smoothly, no backlash, but we'll have to see how it behaves on the proper chassis.

I have some correct-value RF chokes (I used a 1.5mH choke before) and the AF choke on order from Henk and I'm hoping these will arrive in time for me to have the Paraset on the air by Christmas 2020.

73,

John G4EDX
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