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R-4C Low audio output
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Malcolm G4TJK
Just obtained an R-4C from eBay (I don’t recommend this as a source!). The radio appears to have Sherwood mods (see photo). The radio works on all band, but with the RF Gain on Max, and the AF Gain almost on max, the audio output is rather low. Have changed all of the tubes. Not a Drake expert so any thoughts would be valued. |
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Hi, Malcolm.? I presume the S-meter is moving in time with any input signal(s). If yes, check the?1/4" headphone jack in the front of the radio. There may be sufficient corrosion to prevent the shorting contacts of the jack from sending the audio to the speaker jack on the back. The tension on the RCA jack for the speaker may have lessened (a lot). You can retension it by carefully compressing the portion that makes contact with the center pin of the speaker cord RCA plug. 73 ES GL, Bob Loving K9JU Maryville, TN
On Tuesday, March 19, 2024 at 11:22:45 AM EDT, Malcolm G4TJK via groups.io <charlie.porter1@...> wrote:
Just obtained an R-4C from eBay (I don’t recommend this as a source!). The radio appears to have Sherwood mods (see photo). The radio works on all band, but with the RF Gain on Max, and the AF Gain almost on max, the audio output is rather low. Have changed all of the tubes. Not a Drake expert so any thoughts would be valued. |
开云体育
Hello Malcolm,
I am sure you will get plenty of good advice but, for what it is worth, I do not think changing all the tubes was a good idea!
73 Damien B3XER From:[email protected] <[email protected]> on behalf of Malcolm G4TJK via groups.io <charlie.porter1@...>
Sent:?19 March 2024 15:22 To:[email protected] <[email protected]> Subject:?[DRAKE-RADIO] R-4C Low audio output ?
Just obtained an R-4C from eBay (I don’t recommend this as a source!). The radio appears to have Sherwood mods (see photo). The radio works on all band, but with the RF Gain on Max, and the AF Gain almost on max, the audio output is rather low. Have changed all of the tubes. Not a Drake expert so any thoughts would be valued. |
开云体育
Sorry, Damien G3XER
From: [email protected] <[email protected]> on behalf of Damien Mannix <damienmannix@...>
Sent: 19 March 2024 15:43 To: [email protected] <[email protected]> Subject: Re: [DRAKE-RADIO] R-4C Low audio output ?
Hello Malcolm,
I am sure you will get plenty of good advice but, for what it is worth, I do not think changing all the tubes was a good idea!
73 Damien B3XER
From:[email protected] <[email protected]> on behalf of Malcolm G4TJK via groups.io <charlie.porter1@...>
Sent:?19 March 2024 15:22 To:[email protected] <[email protected]> Subject:?[DRAKE-RADIO] R-4C Low audio output ?
Just obtained an R-4C from eBay (I don’t recommend this as a source!). The radio appears to have Sherwood mods (see photo). The radio works on all band, but with the RF Gain on Max, and the AF Gain almost on max, the audio output is rather low. Have changed all of the tubes. Not a Drake expert so any thoughts would be valued. |
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Implementation of the mods is my suspect No. 1. ?I will assume that the audio amp mod was done. ?Look around the work done to install that amp. ?Cold solder joints, broken wires, etc. The extreme variability of the installation of these various mods has caused me to do what others who work on these sets have done and avoid working on them any more. Steve Wedge, W1ES/4 Time flies like an arrow. Fruit flies like a banana. Sent from for iOS On Tue, Mar 19, 2024 at 11:45 AM, Damien Mannix <damienmannix@...> wrote:
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Either stock or with the Sherwood amp, it should be plenty before 12 o’clock. ?You could have component drift or someone used a different pot. Steve Wedge, W1ES/4 Time flies like an arrow. Fruit flies like a banana. Sent from for iOS On Tue, Mar 19, 2024 at 1:17 PM, Malcolm G4TJK via groups.io <charlie.porter1@...> wrote:
Thanks for your thoughts! I get audio, but not the level that I’ve had with other examples. The AF gain is at around the 3pm position all of the time. |
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Not necessarily. The mod is great if done well. ?I would simply look at how well it was installed.? Steve Wedge, W1ES/4 Time flies like an arrow. Fruit flies like a banana. Sent from for iOS On Tue, Mar 19, 2024 at 1:19 PM, Malcolm G4TJK via groups.io <charlie.porter1@...> wrote:
Steve, |
开云体育Either amp, the original or mine, should clip on a typical signal about 3 or 4 o’clock. ?The IF signal into the protect detector should be about 600 mV P-P above the AGC threshold. If the audio amp can’t clip, suspect the product detector and then the amp.Rob, NC0B?
On Mar 19, 2024, at 4:19?PM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
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Rob Sherwood