[ARC5] IIRC Stinson’s solution to sidetone issue
Dave Kirk
w6mqi at yahoo.com
Sun Feb 10 23:26:03 EST 2019
Tom, Making sure I understand correctly Dave installed a spst switch on the line feeding the coil of K51 correct?
Dave
On Sunday, February 10, 2019, 7:23:32 PM PST, Tom Bridgers <tarheel6 at msn.com> wrote:
My memory is not as good as it use to be, but I thought I remember Dave’s solution was related to his interest in listening to the transmitted signal on his SCR-274N receiver that was in a rack and appropriately connected to a BC-456 modulator.
His innovative solution, was to add a spst switch to the rack that enables the sidetone relay in the rack to be toggled off when transmitting.
With the sidetone relay toggled off, the receiver’s normal audio output remains connected to the rack’s headphone jacks.
And as I recall Dave telling me, even though the receivers antenna terminal is grounded (when in transmit mode), the receiver is nonetheless able to hear the transmitted signal and pass it through to the headphone jacks.
As we all know, Dave does not like to add a mod to any military radio system. But this mod was born of necessity...
I hope I remembered it correctly and that my comments help further the sidetone options/issues discussion.
Apologies in advance to Dave for any errors on my part.
-Tom
Sent from my iPhone
> On Feb 10, 2019, at 2:28 PM, arc5-request at mailman.qth.net wrote:
>
> Send ARC5 mailing list submissions to
> arc5 at mailman.qth.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://mailman.qth.net/mailman/listinfo/arc5
> or, via email, send a message with subject or body 'help' to
> arc5-request at mailman.qth.net
>
> You can reach the person managing the list at
> arc5-owner at mailman.qth.net
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of ARC5 digest..."
>
>
> Today's Topics:
>
> 1. Re: SCR-274N side tone level? (Richard Knoppow)
> 2. Re: SCR-274N side tone level? (Dave Kirk)
> 3. Re: SCR-274N side tone level? (David Stinson)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 10 Feb 2019 10:46:17 -0800
> From: Richard Knoppow <1oldlens1 at ix.netcom.com>
> To: arc5 at mailman.qth.net
> Subject: Re: [ARC5] SCR-274N side tone level?
> Message-ID: <b99f9f1b-8eb6-7662-dc5b-166636d1b235 at ix.netcom.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> No, I am talking about both sidetones and mentioned them in
> my post. The come from different places but the load on either
> transformer output is the same. If you put a pad of known
> impedance on the headphone output of the rack it will work for
> either side tone source. The winding on the modulator transformer
> will be affected by the load on the headphone jacks but if its
> loaded by a constant resistance pad of about the value that is
> expected of the headphone line the modulator should work fine. A
> pad will also isolate the headphone line so that changes in
> headphone impedance will have little or no effect on the
> transformer side. Many text books will show you how to make such
> a pad. I suspect David's problem is that he used a low value pot
> that partially shorted the headphone winding on the modulator
> causing some overloading and distortion there. Even a simple L
> pad with the series arm connected to the headphone output would
> eliminate this. If the side tone, either CW or Phone, worked
> originally it will still work.
> I read over the handobook for the SCR-274N before posting.
> Its difficult in some areas because the schematic drawings are
> broken up into sections but it is possible to trace through the
> side tone circuits.
> The phones mentioned are 8K impedance, I have several. 8K is
> the impedance, not the DC resistance as specified in many
> headphones. Resistance is around 2K.
>
>> On 2/10/2019 1:25 AM, Robert Downs via ARC5 wrote:
>> Richard,
>>
>> You are talking about the CW sidetone and Dave was talking about the voice sidetone. Two different circuits in the BC-456.
>>
>> Robert Downs
>>
>>
>> -----Original Message-----
>> From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Richard Knoppow
>> Sent: Sunday, February 10, 2019 01:06
>> To: arc5 at mailman.qth.net
>> Subject: Re: [ARC5] SCR-274N side tone level?
>
>
> --
> Richard Knoppow
> 1oldlens1 at ix.netcom.com
> WB6KBL
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 10 Feb 2019 19:13:59 +0000 (UTC)
> From: Dave Kirk <w6mqi at yahoo.com>
> To: arc5 at mailman.qth.net, David Stinson <arc5 at ix.netcom.com>
> Subject: Re: [ARC5] SCR-274N side tone level?
> Message-ID: <924898192.1272051.1549826039788 at mail.yahoo.com>
> Content-Type: text/plain; charset="utf-8"
>
> Okay guys I need to reset this whole conversation in my original post I mentioned that the CW side tone was too loud along with the phone side tone. My main concern is the CW side tone because I wear headphones while operating CW and the side tone is just ear piercing. So I did some test on the CW side tone, and was able to lower the volume with no problem, but now relay clicking in the headphones is prominent. Funny I didn't hear the relay clacking away in the headphones with the loud side tone:-), fix one problem another appears oh well. Anyway think I'll just let things be have to remember these are WW2 radios not some $10,000 2019 Icom and that's why I like them their quirky, and rough around the edges.
> My next issue is to figure why the BC-455-B 40m receiver drifts so much it takes almost an hour for the receiver to settle down my other command set receivers are very stable.
>
> Dave
> On Sunday, February 10, 2019, 5:06:38 AM PST, David Stinson <arc5 at ix.netcom.com> wrote:
>
> #yiv4608172084 -- filtered {panose-1:2 4 5 3 5 4 6 3 2 4;}#yiv4608172084 filtered {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;}#yiv4608172084 p.yiv4608172084MsoNormal, #yiv4608172084 li.yiv4608172084MsoNormal, #yiv4608172084 div.yiv4608172084MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:12.0pt;font-family:New;color:black;}#yiv4608172084 a:link, #yiv4608172084 span.yiv4608172084MsoHyperlink {color:blue;text-decoration:underline;}#yiv4608172084 a:visited, #yiv4608172084 span.yiv4608172084MsoHyperlinkFollowed {color:purple;text-decoration:underline;}#yiv4608172084 span.yiv4608172084moz-smiley-s1 {}#yiv4608172084 span.yiv4608172084EmailStyle18 {color:#1F497D;}#yiv4608172084 .yiv4608172084MsoChpDefault {font-size:10.0pt;}#yiv4608172084 filtered {margin:1.0in 1.0in 1.0in 1.0in;}#yiv4608172084 div.yiv4608172084WordSection1 {}#yiv4608172084
> Caution:
> If you try putting a pot across the sidetone winding, rather than in series with it,
>
> the impedance change this makes is reflected into the other windings of the
>
> modulation transformer and will change your modulation envelope.? It changed
>
> mine drastically when I tried this.?? In fact, any non-spec load on the sidetone
>
> winding causes tx modulation envelope effects. It?s been a lot of years now
>
> and I don?t remember the exact details, but ended-up abandoning the sidetone
>
> line altogether in my sets.
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: https://www.qsl.net/donate.html
> Message delivered to w6mqi at yahoo.com
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <http://mailman.qth.net/pipermail/arc5/attachments/20190210/ba60030b/attachment-0001.html>
>
> ------------------------------
>
> Message: 3
> Date: Sun, 10 Feb 2019 13:28:00 -0600
> From: "David Stinson" <arc5 at ix.netcom.com>
> To: "ARC-5" <arc5 at mailman.qth.net>
> Subject: Re: [ARC5] SCR-274N side tone level?
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="utf-8"
>
> Try what worked well on the TCS set.
> Connect two 5V Zener diodes across the headphone jack, one
>
> pointed in each direction. Made the headphones on the TCS
>
> as comfortable as any other ham rig. Lots of talk about how
>
> ?it won?t work,? but it works just fine. I don?t explain it;
>
> I just report it. Pic:
> https://photos.app.goo.gl/X6v2VtKWcp75AqQT6
>
> GL OM DE Dave AB5S
>
>
>
>
>
> From: Dave Kirk [mailto:w6mqi at yahoo.com]
> Subject: Re: [ARC5] SCR-274N side tone level?
>
>
>
> Okay guys I need to reset this whole conversation in my original post I mentioned that the CW side tone was too loud along with the phone side tone. My main concern is the CW side tone because I wear headphones while operating CW and the side tone is just ear piercing. So I did some test on the CW side tone, and was able to lower the volume with no problem, but now relay clicking in the headphones is prominent. Funny I didn't hear the relay clacking away in the headphones with the loud side tone:-), fix one problem another appears oh well. Anyway think I'll just let things be have to remember these are WW2 radios not some $10,000 2019 Icom and that's why I like them their quirky, and rough around the edges.
>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <http://mailman.qth.net/pipermail/arc5/attachments/20190210/f416c791/attachment.html>
>
> ------------------------------
>
> _______________________________________________
> ARC5 mailing list
> ARC5 at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/arc5
>
>
> End of ARC5 Digest, Vol 181, Issue 12
> *************************************
______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: https://www.qsl.net/donate.html
Message delivered to w6mqi at yahoo.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20190211/da5840de/attachment-0001.html>
More information about the ARC5
mailing list