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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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18th Dec 2022, 11:10 am | #21 | |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: Marconi TF2701 In Situ RCL Bridge.
Quote:
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18th Dec 2022, 4:40 pm | #22 |
Pentode
Join Date: Jun 2017
Location: Basildon, Essex, UK.
Posts: 186
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Re: Marconi TF2701 In Situ RCL Bridge.
Interesting thread could anyone tell me a source for the TF2701 manual? Google has nothing on it and the conversion tables would be really handy.
Hugh |
19th Dec 2022, 11:49 am | #23 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: Marconi TF2701 In Situ RCL Bridge.
I have made a single page reference card from the graphs for the TF2701.
It's on my web site at http://air-ministry.uk |
19th Dec 2022, 1:33 pm | #24 |
Hexode
Join Date: May 2009
Location: Newcastle, Australia
Posts: 316
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Re: Marconi TF2701 In Situ RCL Bridge.
Greetings all.
(That's appropriate for this time of year.) Thank you once again GMB for going to the trouble of producing the graphs on the one page. Very useful for me. Recently acquired a HP-4815A RF Vector Impedance Meter. Got it going. Used in conjunction with my TF-2701 bridge gives some interesting insight to why some things that should happen; don't. Some years ago I built a book project of a 40 metre transceiver. Could never get it to work. Tried everything. Ended in a box at the back of a back shelf and forgotten. You know when you build a project and you need maybe 6 small parts you order 10. Round figure. This project used small RF chokes for all of the DC feeds rather than resistor / bypass caps. Just playing with the TF-2701 on random components from my workshop and in active repair jobs on the bench. Found a few left over feed chokes from the transceiver project. Chokes measured spot on for the correct value. (This is at the Marconi's test frequency of 80Hz.) (Can't remember the value). Put them on the HP-4815A and they turned out to be self resonant at 7.095 Mhz. Quite a strong parallel resonance at that. All 6 of them! I guess this is why the radio project didn't want to work seeing as it was supposed to work in the 40 metre (7Mhz) band. So just practicing with the Marconi bridge and the HP has been quite informative. Thanks again to everyone that has responded to this thread. I am quite enjoying my TF-2701. Cheers all and the best for the season. Robert. VK2BNM (VK2 Broke No Money.) |
19th Dec 2022, 6:56 pm | #25 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
|
Re: Marconi TF2701 In Situ RCL Bridge.
At RF pretty much any component does not behave like what it says on the can.
The question you always have to ask is "what frequency can it get to before it stops being what it says". The answer is invariably a disappointment! |
26th Dec 2022, 9:44 pm | #26 |
Pentode
Join Date: Jun 2017
Location: Basildon, Essex, UK.
Posts: 186
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Re: Marconi TF2701 In Situ RCL Bridge.
GMB many thanks for the pm and help.
73 Hugh G1AUR |