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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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26th Mar 2019, 6:21 pm | #1 |
Retired Dormant Member
Join Date: Aug 2018
Location: Hunt Valley, Maryland, USA.
Posts: 5
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Clansman Pressel help please
I have a Clansman IB3 intercom box in my vehicle. From there, I have a crew box connected. Instead of using the pressel (PTT), I've connected the headset directly and wired a switch between PTT pin F and E. E is the PTT and headphone return. The problem is that the PTT is active all the time and won't shut off when opening the switch. What am I missing? Does the PTT need to be pulled high when not grounded? I can't find a pressel schematic. The reason I am doing this is so that the cabling has a ww2 appearance. Thanks
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26th Mar 2019, 7:50 pm | #2 |
Heptode
Join Date: Sep 2009
Location: Tonbridge, Kent, UK.
Posts: 686
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Re: Clansman Pressel help please
Assuming you don't want to transmit over a radio, which is what it sounds like from your message, I would use the pressel box set to Live Mic then hide it away somewhere.
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27th Mar 2019, 12:47 pm | #3 |
Heptode
Join Date: May 2008
Location: Selby, North Yorkshire, UK.
Posts: 951
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Re: Clansman Pressel help please
Have you tried with a pressel/standard handset? Are you sure the IB3 and crew box are working properly?
Ive checked the harness manuals and tech EMERs but they dont have the pressel box in them either!
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27th Mar 2019, 2:38 pm | #4 | ||
Retired Dormant Member
Join Date: Aug 2018
Location: Hunt Valley, Maryland, USA.
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Quote:
Quote:
Yes, a pressel (PTT) controls PTT just fine with the IB3 and crew box, I'm trying to make my own period-looking PTT using a switch between E and F to control the Clansman throat mic. |
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27th Mar 2019, 4:25 pm | #5 |
Heptode
Join Date: May 2008
Location: Selby, North Yorkshire, UK.
Posts: 951
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Re: Clansman Pressel help please
Thats fine, just wanted to check you'd ruled out a fault in the rest of the system.
Why on earth do you want to use those gawd awful throat mics!? Have you checked that the switch and plug combination gives the expected continuity readings between pins E and F when not connected to the boxes? And have you tried the switch only without the mic? I think without the audio gear diagrams you'll need to work by 'divide and conquer'!
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I got food in ma belly and a license for ma telly My Blog - http://g7mrv.blogspot.com |
27th Mar 2019, 9:20 pm | #6 |
Heptode
Join Date: Feb 2008
Location: Great Barr, Sandwell, West Midlands, UK.
Posts: 589
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Re: Clansman Pressel help please
Hi,
I read your post with interest as I wired up a harness with similar boxes some years ago and had no issues with it (apart from burbling ANR headsets...!). Our system was just used for audio, with pressels to activate the mics. I have just revisited the wiring diagrams and one point to note is there is no individual PTT wire(s) in the 12-way interconnecting cables. PTT is signalled by current sensing via the mic pair - the boxes placing a low impedance across the relevant A or B mic wires. Radios connected to the harness use this to activate PTT via their harness connector, unlike the hard switch in the pressel box connected to the handset/headset connector. So, if your radios are PTT'ing you may have a too-low impedance arriving permanently across their mic connections in the harness connector? Joe Bell's article written for VMARS may help... http://www.vmarsmanuals.co.uk/newsle..._interface.pdf Cheers Martin G4NCE Last edited by Sparky67; 27th Mar 2019 at 9:26 pm. |
28th Mar 2019, 4:25 pm | #7 |
Retired Dormant Member
Join Date: Aug 2018
Location: Hunt Valley, Maryland, USA.
Posts: 5
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Re: Clansman Pressel help please
Thanks. Last night I took apart a pressel to find that pressel switch is multi-pole and also controls one of the mic signal lines as well as the PTT. My original WW2 switch is only single pole, so it looks like I would have to operate in hot mic all the time, unless I repurpose my switch to control the mic signal (and wire the PTT to be on all the time). Would that work, or would the hi Z be susceptible to creating noise?
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28th Mar 2019, 11:51 pm | #8 |
Heptode
Join Date: Sep 2009
Location: Tonbridge, Kent, UK.
Posts: 686
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Re: Clansman Pressel help please
I have an armoured vehicle with Clansman fitted using an IB3 and crew boxes as you have. I run the Pressels in Live Mic and use that Crew Box position as well. No problem with noise while using A vehicle headsets and it means that for the driver especially the intercom is hands free operation. (Unless he wants to use a radio). The Clansman microphones are noise cancelling which no doubt helps.
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