IF frequencies on Telefunken Bajazzo circa 1955 and 1956 - UK Vintage Radio Repair and Restoration Discussion Forum

georgesgiralt · 21st Jan 2010, 12:26 am

Hi !
I own a couple of B7G based valves portable from Telefunken. They both have VHF FM (87.5 to 100 MHz).
The valves complement is as follow DC90, DF96, DK96 (55)- DK92 (56), DF96, DF96, DAF96, DL94 (55) and DL94+DL94 (56).
So they look really identical, but,
The 1955 set has an IF frequency of 10.7 MHz from the VHF head up to detection.
The 1956 set has an IF frequency of 10.7 MHz for the VHF head, but it is converted to 8.35 MHz strait out of the VHF head, and it stays at 8.35 MHz up to the detection.
Both are really good sets on FM, able to separate strong over modulated signals (as are the "junk" radios these days), sensitive, sound is very good, etc...
So I wonder what could have been the rationale for the modification of the IF strip ?
Benefits ? or else ?
What do you think ?
Thanks a lo for your help and advice !

21st Jan 2010, 12:26 am	#1
georgesgiralt Hexode Join Date: Jul 2008 Location: Toulouse, France Posts: 406	IF frequencies on Telefunken Bajazzo circa 1955 and 1956 Hi ! I own a couple of B7G based valves portable from Telefunken. They both have VHF FM (87.5 to 100 MHz). The valves complement is as follow DC90, DF96, DK96 (55)- DK92 (56), DF96, DF96, DAF96, DL94 (55) and DL94+DL94 (56). So they look really identical, but, The 1955 set has an IF frequency of 10.7 MHz from the VHF head up to detection. The 1956 set has an IF frequency of 10.7 MHz for the VHF head, but it is converted to 8.35 MHz strait out of the VHF head, and it stays at 8.35 MHz up to the detection. Both are really good sets on FM, able to separate strong over modulated signals (as are the "junk" radios these days), sensitive, sound is very good, etc... So I wonder what could have been the rationale for the modification of the IF strip ? Benefits ? or else ? What do you think ? Thanks a lo for your help and advice !