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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE! |
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6th Sep 2015, 6:43 pm | #1 |
Tetrode
Join Date: Apr 2009
Location: Towcester, Northamptonshire, UK.
Posts: 92
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Marconi TF801A now working.
I have just finished and tested the TF801A RF signal generator and it is oscillating (CW & MCW) on all ranges from 8MHz to 260MHz. I have not only changed all the electrolytics, but replaced the EC53 triode, but also replaced the two EA50 diodes with Silicon BAW62 signal diodes. I am getting 330mV P-P wirh 0dB on the attenuator on the 8 to 19 MHz range.
The inside of this instrument is a work of art! Here are some photographs. Neil
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6th Sep 2015, 11:12 pm | #2 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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Re: Marconi TF801A now working.
Well done! It's nice to see some of this classic and very high quality test gear restored to working order.
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Phil Optimist [n]: One who is not in possession of the full facts |
7th Sep 2015, 7:25 am | #3 |
Tetrode
Join Date: Apr 2009
Location: Towcester, Northamptonshire, UK.
Posts: 92
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Re: Marconi TF801A now working.
I am amazed at how stable the frequency is when set. The fine tuning offset control lets you set a very precise frequency. Also, given the quality of this instrument, the attenuators are incredible quality. I shall use this on my next valve comms receiver build!
Neil
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7th Sep 2015, 10:56 am | #4 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,223
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Re: Marconi TF801A now working.
Congratulations on an excellent job, and for giving it a good home.
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7th Sep 2015, 10:59 am | #5 |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,509
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Re: Marconi TF801A now working.
If it is the one I recall, it is a very nice piece of kit. The one I had was lacking an oscillator valve and being unable to get a replacement, I used a FET instead. The carrier strength was a bit up & down over the range, but it did the job.
Interesting to see the Advance genny in the back. I also have one of those, not that it gets much use since I built a DDS unit. |
7th Sep 2015, 11:17 pm | #6 |
Tetrode
Join Date: Apr 2009
Location: Towcester, Northamptonshire, UK.
Posts: 92
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Re: Marconi TF801A now working.
Dave,
Thanks for the generator, I ended up changing all the electrolytics for modern capacitance equivalents. All the large valves worked fine. I decided to slot the Silicon diodes into the EA50 valve holders and they also worled fine.
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An engineer makes for a penny what a scientist makes for a pound! |
7th Sep 2015, 11:20 pm | #7 |
Tetrode
Join Date: Apr 2009
Location: Towcester, Northamptonshire, UK.
Posts: 92
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Re: Marconi TF801A now working.
Les,
I purchased an EC53 from ebay for about £6. I thought about the FET option, but the RF level pot can apply around 200V onto the EC53's anode for some bands. I also have an Advance P1 genny which also works well.
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An engineer makes for a penny what a scientist makes for a pound! |