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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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22nd Feb 2019, 8:45 am | #1 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
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4CX350f valves
I'm considering a vintage vhf amplifier but I am.pretty sure the valve, a 4cx350f, is now part of the vast array of materials known as unobtanium. Is this so? It might make me reconsider...
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David, G4YVM. |
22nd Feb 2019, 9:02 am | #2 |
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Re: 4CX350f valves
There are some around, but old Eimac ceramic toobs were known to sometimes be a bit leaky. 4CX250B and 8877s seem to have been more common.
Try asking on an EME forum, or an ad in Dubus. David
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22nd Feb 2019, 9:12 am | #3 |
Heptode
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Re: 4CX350f valves
Thanks
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David, G4YVM. |
22nd Feb 2019, 9:19 am | #4 |
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Re: 4CX350f valves
There are also the G3SEK triode and tetrode control boards which are worth investigating, also Ian did the VHF/UHF DX book for the RSGB and if you don't have a copy, it's well worth hunting one.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
22nd Feb 2019, 9:42 am | #5 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
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Re: 4CX350f valves
Coincidence...i worked GM3SEK a couple of weeks back on 2m tropo from Salisbury. I was dead chuffed.
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David, G4YVM. |
22nd Feb 2019, 10:16 am | #6 |
Dekatron
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Location: W.Butterwick, near Doncaster UK.
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Re: 4CX350f valves
I bought a spare 4CX350F a year or so back for Nagi at a good price (new) off eBay.
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22nd Feb 2019, 10:19 am | #7 |
Heptode
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
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Re: 4CX350f valves
The VHF/UHF DX book is now available as a free download, I think from Ian's web site. (I know its "not the same" as a book but you can get it!)
They warn the info is dated but it provides excellent background material 73 Fred G4BWP |
22nd Feb 2019, 10:26 am | #8 |
Heptode
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
Posts: 612
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Re: 4CX350f valves
Plenty around Europe on eBay including NOS (£39) and one sealed in a US military can £128 or offer
73 Fred G4BWP |
22nd Feb 2019, 11:28 am | #9 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
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Re: 4CX350f valves
The G3SEK boards are definitely worth studying: a point often missed by some designers of amplifiers using the 4X-series of tubes is that the screen-grid supply needs to be able to both source *and sink* current.
The valves are still available - new - from CPII in the 'states [the company which now owns what us oldtimers still call Eitel McCulloch] but the prices are very much aimed at the military/industrial-sector purchaser! The "care and feeding of power grid tubes" design-application notes - essential reading for anyone using these valves - are also available to download from https://www.cpii.com/library.cfm/9 |
22nd Feb 2019, 11:28 am | #10 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
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Re: 4CX350f valves
Thanks chaps.
The control boards from Ian seem very reasonably priced although he warns this is their final year of production.
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