Philco A3658 AM-FM radio set. - UK Vintage Radio Repair and Restoration Discussion Forum

FERNSEH · 17th Sep 2006, 11:16 pm

This set was acquired recently, donated by Forum member System A.

The Philco A3658 was manufactured in 1955 and employs six valves and a selenium HT rectifier. The valve line-up is: Brimar 12AT7 FM RF amplifier and oscillator-mixer. Brimar 12AH8 AM frequency changer and 1st IF amplifier on FM. Brimar 6BJ6 IF amplifier. Mullard EABC80 AM-FM demodulator and audio amplifier. Brimar 6BW6 output valve. A Brimar 6E5 magic eye tuning indicator.

The bakelite cabinet is finished with a wood grain effect, in reality it looks quite good.
Another easy set to get going. The usual things like the AF amplifier coupling capacitors required replacement. FM reception was improved by replacing the 12AT7. The FM band covers only 88 to 101Mhz, Classic FM can received at the extreme end of the tuning range.
Some instability and motorboating was experienced at the higher frequency end of the FM band. Even after removing the 12AT7 the motorboating was still apparent. This turned to be that critical positioning of components around the 12AH8 was required. All the decoupling caps were OK.

This is a truly impressive receiver, I know that some early FM sets are not that good, but this one certainly gives a good account of itself.
It is now the workshop radio.

DFWB.

newlite4 · 18th Sep 2006, 9:33 am

This set is unusual for a mid '50s one in that it has an EM34 type octal magic eye rather than an EM84 type which would be more commonplace for a later set of this age. A very nice looking set, it must be a pleasure to use.
Neil

17th Sep 2006, 11:16 pm	#1
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Philco A3658 AM-FM radio set. This set was acquired recently, donated by Forum member System A. The Philco A3658 was manufactured in 1955 and employs six valves and a selenium HT rectifier. The valve line-up is: Brimar 12AT7 FM RF amplifier and oscillator-mixer. Brimar 12AH8 AM frequency changer and 1st IF amplifier on FM. Brimar 6BJ6 IF amplifier. Mullard EABC80 AM-FM demodulator and audio amplifier. Brimar 6BW6 output valve. A Brimar 6E5 magic eye tuning indicator. The bakelite cabinet is finished with a wood grain effect, in reality it looks quite good. Another easy set to get going. The usual things like the AF amplifier coupling capacitors required replacement. FM reception was improved by replacing the 12AT7. The FM band covers only 88 to 101Mhz, Classic FM can received at the extreme end of the tuning range. Some instability and motorboating was experienced at the higher frequency end of the FM band. Even after removing the 12AT7 the motorboating was still apparent. This turned to be that critical positioning of components around the 12AH8 was required. All the decoupling caps were OK. This is a truly impressive receiver, I know that some early FM sets are not that good, but this one certainly gives a good account of itself. It is now the workshop radio. DFWB. Attached Thumbnails

18th Sep 2006, 9:33 am	#2
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,805	Re: Philco A3658 AM-FM radio set. This set is unusual for a mid '50s one in that it has an EM34 type octal magic eye rather than an EM84 type which would be more commonplace for a later set of this age. A very nice looking set, it must be a pleasure to use. Neil