Ferranti 105. Poor short wave reception. - UK Vintage Radio Repair and Restoration Discussion Forum

MALC SCOTT · 10th Dec 2009, 10:02 pm

Hi, i have just fully restored this nice old radio which i saved from a skip.
All of the wax caps have been replaced as well as out of spec resistors.
A full set of brand new valves have also been fitted. The set now works fantastic on MW/LW but is not very good
at all on SW. Very few stations, even at night with a 30ft external aerial.
The wavechange switch is ok and the valve bases have been cleaned with a fibre tip pen. Is this normal for this model or have i missed something?
Cheers, Malc.

paulsherwin · 10th Dec 2009, 10:11 pm

Just to state the obvious, have you compared the performance with a similar radio using the same aerial? There are many fewer SW broadcasts than there used to be, especially in Europe, and the bands can be very quiet at some times.

If the radio really is performing badly, then the standard checks apply - wavechange switch, coil continuity, broken tags etc. If all appears well you could try an RF realignment, which it's possible to do by ear using broadcast signals.

Paul

Steve_P · 10th Dec 2009, 10:15 pm

C10 is a possibility. Try adjusting L4/C33.

Cheers,

Steve P.

MALC SCOTT · 10th Dec 2009, 10:23 pm

Paul, i have tried several 1950,s era sets on SW with the same aerial and there are loads more stations.
Steve, i will try C10 and report back, thanks to both of you for a fast reply.

mister valve · 14th Dec 2009, 10:46 am

C13 (0.004MFD) the shortwave Osc. Padder cap., Could be at fault. Also with a low I.F. (470kHz), it is posible to get 'double spotting' at twice the I.F. frequency apart, at the H.F. end of the shortwave band. Make sure that the local oscillator is running 470kHz above the incomming aerial signal, otherwise poor tracking will result causing the simptoms you descibed.

Sometimes, a very long Aerial is not ideal on Short-Wave !!

MALC SCOTT · 17th Dec 2009, 8:56 pm

Hi, i have replaced C10/13 and adusted L4C33. This has improved SW.
When i replaced the external aerial for a couple of feet of solder braid the set now picks up loads of stations from around the world, loud and clear.

dr peppers · 17th Dec 2009, 10:21 pm

Theres probably a loading coil within the set for the aerial, matching the aerial input for a shorter more practical length, fitting a 30ft silver rod could mismatch the input.
You can improve things if you really want by making a co-linear type aerial from co-ax, it would work without modding the set, but probably isnt worth the effort with only a few stations on air.
A freind had what looked like a ferranti 105 set on his farm when we were kids, we had fun with shortwave listening, I think that set went in the skip too, shame.

mister valve · 18th Dec 2009, 8:08 pm

Just had a thought; try connecting a passive 'Aerial tuning unit' (ATU) and your 30ft external Aerial. This will ensure that the Aerial impedance will always match your receiver's, thus ensuring maximum signal transfer current.

10th Dec 2009, 10:02 pm	#1
MALC SCOTT Octode Join Date: Aug 2006 Location: Willington, County Durham, UK. Posts: 1,499	Ferranti 105. Poor short wave reception. Hi, i have just fully restored this nice old radio which i saved from a skip. All of the wax caps have been replaced as well as out of spec resistors. A full set of brand new valves have also been fitted. The set now works fantastic on MW/LW but is not very good at all on SW. Very few stations, even at night with a 30ft external aerial. The wavechange switch is ok and the valve bases have been cleaned with a fibre tip pen. Is this normal for this model or have i missed something? Cheers, Malc. __________________ Malc Scott

10th Dec 2009, 10:11 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Ferranti 105. Poor short wave reception. Just to state the obvious, have you compared the performance with a similar radio using the same aerial? There are many fewer SW broadcasts than there used to be, especially in Europe, and the bands can be very quiet at some times. If the radio really is performing badly, then the standard checks apply - wavechange switch, coil continuity, broken tags etc. If all appears well you could try an RF realignment, which it's possible to do by ear using broadcast signals. Paul

10th Dec 2009, 10:15 pm	#3
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Ferranti 105. Poor short wave reception. C10 is a possibility. Try adjusting L4/C33. 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...?

10th Dec 2009, 10:23 pm	#4
MALC SCOTT Octode Join Date: Aug 2006 Location: Willington, County Durham, UK. Posts: 1,499	Re: Ferranti 105. Poor short wave reception. Paul, i have tried several 1950,s era sets on SW with the same aerial and there are loads more stations. Steve, i will try C10 and report back, thanks to both of you for a fast reply. __________________ Malc Scott

14th Dec 2009, 10:46 am	#5
mister valve Hexode Join Date: Aug 2009 Location: Blackpool, Lancashire, UK. Posts: 311	Re: Ferranti 105. Poor short wave reception. C13 (0.004MFD) the shortwave Osc. Padder cap., Could be at fault. Also with a low I.F. (470kHz), it is posible to get 'double spotting' at twice the I.F. frequency apart, at the H.F. end of the shortwave band. Make sure that the local oscillator is running 470kHz above the incomming aerial signal, otherwise poor tracking will result causing the simptoms you descibed. Sometimes, a very long Aerial is not ideal on Short-Wave !!

17th Dec 2009, 8:56 pm	#6
MALC SCOTT Octode Join Date: Aug 2006 Location: Willington, County Durham, UK. Posts: 1,499	Re: Ferranti 105. Poor short wave reception. Hi, i have replaced C10/13 and adusted L4C33. This has improved SW. When i replaced the external aerial for a couple of feet of solder braid the set now picks up loads of stations from around the world, loud and clear. __________________ Malc Scott

17th Dec 2009, 10:21 pm	#7
dr peppers Retired Dormant Member Join Date: Nov 2009 Location: Lancashire, UK. Posts: 67	Re: Ferranti 105. Poor short wave reception. Theres probably a loading coil within the set for the aerial, matching the aerial input for a shorter more practical length, fitting a 30ft silver rod could mismatch the input. You can improve things if you really want by making a co-linear type aerial from co-ax, it would work without modding the set, but probably isnt worth the effort with only a few stations on air. A freind had what looked like a ferranti 105 set on his farm when we were kids, we had fun with shortwave listening, I think that set went in the skip too, shame. Last edited by dr peppers; 17th Dec 2009 at 10:34 pm.

18th Dec 2009, 8:08 pm	#8
mister valve Hexode Join Date: Aug 2009 Location: Blackpool, Lancashire, UK. Posts: 311	Re: Ferranti 105. Poor short wave reception. Just had a thought; try connecting a passive 'Aerial tuning unit' (ATU) and your 30ft external Aerial. This will ensure that the Aerial impedance will always match your receiver's, thus ensuring maximum signal transfer current.