Marconi 6460 Power meter, faulty - UK Vintage Radio Repair and Restoration Discussion Forum

NickG0HIK · 6th Nov 2018, 8:41 pm

I've fancied one of these for a while and recently obtained one.

As suspected, it is faulty. I dont know anything about these pieces of kit.

The meter is at zero without the head plugged in, with the head in place the meter will not zero and is in different positions depending which range is selected.
I put some into the head and the meter reading did not change.

Is it the head U/S ? or do I have a chance of a repair ?

Do the heads turn up?

Does anyone have a circuit/manual.

Thanks

Nick

orbanp1 · 7th Nov 2018, 1:54 pm

Hi Nick,

Here is a manual for your instrument, that should help:
https://ia600207.us.archive.org/28/i...ower_Meter.pdf

Looks like it can have different power heads. Which one do you have?

Regards, Peter

WME_bill · 7th Nov 2018, 9:07 pm

Marconi-Sanders 6460.
The head is the critical thing. But when I acquired mine, I found that the flexible leads of the cable had fractured just behind the head.
When repaired, and it was very fiddley, it worked well.
Be careful when resoldering, as it uses special solder with the low thermal voltage wires. Do it quickly, with a nice clean iron, and the minimum of new solder.
I see the manual suggested by Peter -orbanp1- includes details of the heads, which are usually omitted and also how to test the head itself. The head is bought in from General Microwave Corporation in US, model 420 series. Thin Film Element.

The heads and connecting cable never appear anywhere, just like the heads for the HP power meters. I have the meter for the HP432A sitting here, but no thermistor head 478 or 8478. Anyone like the Meter itself?
wme_bill

NickG0HIK · 7th Nov 2018, 9:15 pm

Thanks for the manual Peter, that should help.

The head that it came with would be very useful it's the 6421, 10MHz to 12GHz 100mW.

I'll check the wiring of the head, thanks for the info.

It is on the "To Do" pile, but hopefully it will get looked at soon, I'll report back.

Regards

Nick

6th Nov 2018, 8:41 pm	#1
NickG0HIK Hexode Join Date: Jul 2010 Location: Ireleth-in-Furness, Cumbria, UK. Posts: 286	Marconi 6460 Power meter, faulty I've fancied one of these for a while and recently obtained one. As suspected, it is faulty. I dont know anything about these pieces of kit. The meter is at zero without the head plugged in, with the head in place the meter will not zero and is in different positions depending which range is selected. I put some into the head and the meter reading did not change. Is it the head U/S ? or do I have a chance of a repair ? Do the heads turn up? Does anyone have a circuit/manual. Thanks Nick

7th Nov 2018, 1:54 pm	#2
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Marconi 6460 Power meter, faulty Hi Nick, Here is a manual for your instrument, that should help: https://ia600207.us.archive.org/28/i...ower_Meter.pdf Looks like it can have different power heads. Which one do you have? Regards, Peter

7th Nov 2018, 9:07 pm	#3
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: Marconi 6460 Power meter, faulty Marconi-Sanders 6460. The head is the critical thing. But when I acquired mine, I found that the flexible leads of the cable had fractured just behind the head. When repaired, and it was very fiddley, it worked well. Be careful when resoldering, as it uses special solder with the low thermal voltage wires. Do it quickly, with a nice clean iron, and the minimum of new solder. I see the manual suggested by Peter -orbanp1- includes details of the heads, which are usually omitted and also how to test the head itself. The head is bought in from General Microwave Corporation in US, model 420 series. Thin Film Element. The heads and connecting cable never appear anywhere, just like the heads for the HP power meters. I have the meter for the HP432A sitting here, but no thermistor head 478 or 8478. Anyone like the Meter itself? wme_bill Last edited by WME_bill; 7th Nov 2018 at 9:16 pm.

7th Nov 2018, 9:15 pm	#4
NickG0HIK Hexode Join Date: Jul 2010 Location: Ireleth-in-Furness, Cumbria, UK. Posts: 286	Re: Marconi 6460 Power meter, faulty Thanks for the manual Peter, that should help. The head that it came with would be very useful it's the 6421, 10MHz to 12GHz 100mW. I'll check the wiring of the head, thanks for the info. It is on the "To Do" pile, but hopefully it will get looked at soon, I'll report back. Regards Nick