FT-101Z help requested please - UK Vintage Radio Repair and Restoration Discussion Forum

spicesimmer · 13th Nov 2014, 10:54 pm

Hi All,
I bought a FT-101Z that works fine on receive but had a burnt out PA choke and two rather blackened 6146 valves.

The choke and the valves have now been replaced so I connected a dummy load and followed the Transmitter Tuning procedure.

The bias pot VR1001 only gives a max of 25mA IC on the meter instead of 50mA (with all the controls at minimum). If I advance the DRIVE pot slightly to give 50mA there is some 'banging' so I turned it off straight away.

The voltages on the RECT B PCB are:
AC250V = 250Vac
AC190V = 186Vac
AC120V = 136Vac
TX12V = 11Vdc

300V = 343Vdc
210V = 253Vdc
180V = 237Vdc
160V = 226Vdc
-100V = -143Vdc
BIAS 6146B = -38Vdc

Voltages on the RECT A PCB are:
AC14V = 12Vac
320V = 453V

12V = 12Vdc
8V = 8Vdc
900V = 910V

Any help would be greatly appreciated,
Kind regards....spicesimmer

Nuvistor · 14th Nov 2014, 9:18 am

This thread is from a few days ago with some information.
https://www.vintage-radio.net/forum/...ad.php?t=81858

note David's (Radio Wrangler) comment about searching for articles from Harry Leeming G3LLL, I think Harry used to write articles for Practical Wireless.

Bazz4CQJ · 14th Nov 2014, 2:49 pm

Leeming's detailed articles are on the web somewhere for certain; I recall downloading them when I was looking at a FT101 some years ago, but never bought it.

B

HamishBoxer · 14th Nov 2014, 4:22 pm

foxtango.org/ft101/foxtangoft101hist.htm

sentinel040 · 19th Nov 2014, 8:54 pm

Quote:

...I think Harry used to write articles for Practical Wireless.

He still does, having a "column", well several pages usually. He provides contact details for people asking advice.

73

Ian (G8KSZ)

Richard675 · 24th Nov 2014, 10:44 am

Yes, read G3LLL's notes and fit the suggested HV safety capacitors and check over carefully all of the HT circuitry.

The "banging" you mention sounds like flashover in the PA valves which will kill them in seconds and destroy the HV rectifier board as well.....

13th Nov 2014, 10:54 pm	#1
spicesimmer Retired Dormant Member Join Date: Aug 2012 Location: Eastbourne, East Sussex, UK. Posts: 11	FT-101Z help requested please Hi All, I bought a FT-101Z that works fine on receive but had a burnt out PA choke and two rather blackened 6146 valves. The choke and the valves have now been replaced so I connected a dummy load and followed the Transmitter Tuning procedure. The bias pot VR1001 only gives a max of 25mA IC on the meter instead of 50mA (with all the controls at minimum). If I advance the DRIVE pot slightly to give 50mA there is some 'banging' so I turned it off straight away. The voltages on the RECT B PCB are: AC250V = 250Vac AC190V = 186Vac AC120V = 136Vac TX12V = 11Vdc 300V = 343Vdc 210V = 253Vdc 180V = 237Vdc 160V = 226Vdc -100V = -143Vdc BIAS 6146B = -38Vdc Voltages on the RECT A PCB are: AC14V = 12Vac 320V = 453V 12V = 12Vdc 8V = 8Vdc 900V = 910V Any help would be greatly appreciated, Kind regards....spicesimmer

14th Nov 2014, 9:18 am	#2
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: FT-101Z help requested please This thread is from a few days ago with some information. https://www.vintage-radio.net/forum/...ad.php?t=81858 note David's (Radio Wrangler) comment about searching for articles from Harry Leeming G3LLL, I think Harry used to write articles for Practical Wireless.

14th Nov 2014, 2:49 pm	#3
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: FT-101Z help requested please Leeming's detailed articles are on the web somewhere for certain; I recall downloading them when I was looking at a FT101 some years ago, but never bought it. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

14th Nov 2014, 4:22 pm	#4
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: FT-101Z help requested please foxtango.org/ft101/foxtangoft101hist.htm __________________ G8JET BVWS Archivist and Member V.M.A.R.S

24th Nov 2014, 10:44 am	#6
Richard675 Pentode Join Date: Jun 2009 Location: Braintree, Essex, UK. Posts: 170	Re: FT-101Z help requested please Yes, read G3LLL's notes and fit the suggested HV safety capacitors and check over carefully all of the HT circuitry. The "banging" you mention sounds like flashover in the PA valves which will kill them in seconds and destroy the HV rectifier board as well.....