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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 29th Aug 2017, 1:22 pm   #1
SteveCG
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Default Hacker RP18 Sovereign

The VHF section of this Hacker no-longer works. Long Wave and Medium Wave are fine.

Being of the age where the VHF/FM IF unit used the dreaded AF114 Transistors I assumed that it was one of them that had 'tin-whiskered' - however this, I think, is not the case.

The radio uses a German made tuner "G*****" the rest of the name is illegible. I have tried looking for the LO leakage signal - nothing. I've even tried looking for the 10.7 Mc/s IF output whilst tuning across the band - nothing there either. So I suspect I have a failed LO transistor.

My question is this: Are these tuners generally reliable?

BTW the supply voltage to the tuner was about 7.5 volts
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Old 29th Aug 2017, 1:27 pm   #2
G6Tanuki
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Default Re: Hacker RP18 Sovereign

Gorler? They made a lot of FM-tuner-modules in the 60s and 70s.
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Old 29th Aug 2017, 1:30 pm   #3
ms660
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Default Re: Hacker RP18 Sovereign

Gorler from all accounts.

According to this they use AF121, AF125 types:

http://www.radiomuseum.org/r/hacker_..._rp18rp_1.html

Lawrence.
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Old 29th Aug 2017, 2:06 pm   #4
paulsherwin
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Default Re: Hacker RP18 Sovereign

The AF12x series are not known to be unreliable, but failure is still possible of course.
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Old 30th Aug 2017, 11:16 am   #5
SteveCG
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Default Re: Hacker RP18 Sovereign

Folks, indeed it is a Gorler.

A couple of voltages - as measured with a DMM.

For the main battery voltage of 16.9 V, I have +7.56 V on pin 6 of the tuner module wrt the chassis. This pin has the red colour code HT wire connected to it and also a 0.1 uF polyester capacitor connected to pin 4 which in turn is linked to the chassis.
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Old 31st Aug 2017, 2:46 pm   #6
SteveCG
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Default Re: Hacker RP18 Sovereign

Some more tuner voltage readings. Can anybody tell me if they are approximately what they should be?

Gorler tuner module pin-outs; voltages measured with a DMM wrt the chassis:

1 chassis
2 Green lead, 0V
3 Orange lead, +6.11V
4 chassis
5 Blue lead, 0V
6 Red lead, +7.4V
7 Green lead, (I/F output)

I've included the lead insulation colour - just in case Hacker had a 'house style'
Also the voltages are slightly different to those before because the PSU is unregulated and the mains voltage was 5 Volts lower the second time.
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