Weak f.m on Ferguson 382U radio - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Hunts smoothing bomb · 29th Oct 2009, 10:59 pm

Hi,

I had similar probs with a Murphy U502, after changing the caps decoupling the two screens of the I.F. amps the radio played excellently. (I think they were 0.01uf)

Cheers

telstar · 31st Oct 2009, 11:15 pm

Hi Lee. Many thanks for your reply. I tried changing both screen grid de-coupler caps, both rated at 4700pF, but to no avail.
However, I did note the following differences in voltages on the UCH81 valve.
Switched to f.m band, the screen grid voltage on pin one read 100 volts, and the anode voltage on pin 6 read 135 volts.
When switched to m.w band, the screen grid voltage was the same as f.m, but the anode voltage read a healthy 180 volts. I wonder if the fault lies between the UCH81 and UF89 valves?
There is a ceramic coupling cap that I have not replaced yet, it is between the sg2 on the UCH81 valve and the I.F.T F.M.
Cheers
Mike

telstar · 10th Nov 2009, 8:18 pm

Hi. I managed to obtain a copy of the BRTR service sheet for the Ferguson 382U radio, and the details of the voltage for the UCH81 anode, when switched to f.m was actually the same as the measurement that I took for it earlier. The tubular ceramic caps seem to be quite reliable in these old radios, but I did replace them.
I noticed that the grid stopper resistor (UL84)had gone up in value by at least 2kohm, and replacing it did make some improvements, but still no f.m.
I will keep on trying with this project, as it brings memories of a 382U that my grandparents had in 1961, when they lived in a cottage in Rendham, Suffolk.
Normally, I do not have much problems with a.m/f.m radios, but this one is a bit of a menace to sort out.
Cheers
Mike

Steve_P · 10th Nov 2009, 11:28 pm

Undo he FM box and look at L1/L2 and try a tweak of L3.

Cheers,

Steve P.

telstar · 11th Nov 2009, 8:31 pm

Hi. Many thanks for the reply. I might try that, and see if things improve.
I am beginning to wonder, though, if the brass cog that an engineer made for me, to activate the w/c switch (replacing the broken plastic one), is causing the switch to bypass the f.m contacts, but making good contact with the long and medium wave bands ? The small pointer on the w/c switch knob should be actually "flush" with the f.m, m.w, l.w, gram markings shown on the dial, but it is slightly out.
I wonder if the other guy on this forum that had a w/c gear made for his 382U radio can let me have details of his supplier ? I might try and contact him, should I find if there is a fault on the cog that I have.
Cheers
Mike

Steve_P · 11th Nov 2009, 9:21 pm

Switch to VHF. Take the relevant wires off the Wavechange Control and wire them directly. See if that improves it. If it does, then the Wavechange Control is at fault.

Cheers,

Steve P.

telstar · 13th Nov 2009, 8:24 pm

Hi Steve. I will try and remove the relevant wires soon and join them directly. At present, I know that the h.t is being switched via S1A (B.R.T.R sheet R124), so that switch section must be ok.
Cheers
Mike

29th Oct 2009, 10:59 pm	#21
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: Weak f.m on Ferguson 382U radio Hi, I had similar probs with a Murphy U502, after changing the caps decoupling the two screens of the I.F. amps the radio played excellently. (I think they were 0.01uf) Cheers __________________ Lee

31st Oct 2009, 11:15 pm	#22
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,593	Re: Weak f.m on Ferguson 382U radio Hi Lee. Many thanks for your reply. I tried changing both screen grid de-coupler caps, both rated at 4700pF, but to no avail. However, I did note the following differences in voltages on the UCH81 valve. Switched to f.m band, the screen grid voltage on pin one read 100 volts, and the anode voltage on pin 6 read 135 volts. When switched to m.w band, the screen grid voltage was the same as f.m, but the anode voltage read a healthy 180 volts. I wonder if the fault lies between the UCH81 and UF89 valves? There is a ceramic coupling cap that I have not replaced yet, it is between the sg2 on the UCH81 valve and the I.F.T F.M. Cheers Mike

10th Nov 2009, 8:18 pm	#23
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,593	Re: Weak f.m on Ferguson 382U radio Hi. I managed to obtain a copy of the BRTR service sheet for the Ferguson 382U radio, and the details of the voltage for the UCH81 anode, when switched to f.m was actually the same as the measurement that I took for it earlier. The tubular ceramic caps seem to be quite reliable in these old radios, but I did replace them. I noticed that the grid stopper resistor (UL84)had gone up in value by at least 2kohm, and replacing it did make some improvements, but still no f.m. I will keep on trying with this project, as it brings memories of a 382U that my grandparents had in 1961, when they lived in a cottage in Rendham, Suffolk. Normally, I do not have much problems with a.m/f.m radios, but this one is a bit of a menace to sort out. Cheers Mike

10th Nov 2009, 11:28 pm	#24
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Weak f.m on Ferguson 382U radio Undo he FM box and look at L1/L2 and try a tweak of L3. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

11th Nov 2009, 8:31 pm	#25
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,593	Re: Weak f.m on Ferguson 382U radio Hi. Many thanks for the reply. I might try that, and see if things improve. I am beginning to wonder, though, if the brass cog that an engineer made for me, to activate the w/c switch (replacing the broken plastic one), is causing the switch to bypass the f.m contacts, but making good contact with the long and medium wave bands ? The small pointer on the w/c switch knob should be actually "flush" with the f.m, m.w, l.w, gram markings shown on the dial, but it is slightly out. I wonder if the other guy on this forum that had a w/c gear made for his 382U radio can let me have details of his supplier ? I might try and contact him, should I find if there is a fault on the cog that I have. Cheers Mike

11th Nov 2009, 9:21 pm	#26
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Weak f.m on Ferguson 382U radio Switch to VHF. Take the relevant wires off the Wavechange Control and wire them directly. See if that improves it. If it does, then the Wavechange Control is at fault. Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

13th Nov 2009, 8:24 pm	#27
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,593	Re: Weak f.m on Ferguson 382U radio Hi Steve. I will try and remove the relevant wires soon and join them directly. At present, I know that the h.t is being switched via S1A (B.R.T.R sheet R124), so that switch section must be ok. Cheers Mike