[Central-Electronics] 200V transmit bandwidth

Tue Mar 2 12:03:22 EST 2021

Thanks for the update Jon.  Looks like I should have pulled out the schematic before I sent the comment...

Regards, Dennis, k0eoo

-----Original Message-----
From: Jon Kannegaard <kannegaard at gmail.com> 
Sent: Tuesday, March 02, 2021 9:43 AM
To: radioart at frontiernet.net
Cc: ranickels at gmail.com; Jim Candela <jcandela11 at outlook.com>; central-electronics at mailman.qth.net; Kihwal Lee <kihwal at yahoo.com>
Subject: Re: [Central-Electronics] 200V transmit bandwidth

Dennis,

I’m pretty sure the phase shift is after the BPF. BPFs often scramble the phases, shifting some frequencies more than others.  I don’t think this matters before the 100V phase shift network. Some folks consider this phase scrambling a good thing. “Phase rotation” is a feature of some audio processing equipment.

I have a home brew band pass filter before the audio input on my 100V. It does phase rotation whether I wanted it or not. I can set the band pass to anything I want. This does not seem to affect anything despite the strong arguments for and against you can find on AMFONE. The 100V filter is bypassed.

Gary says hello

Jon, K6JEK

> On Mar 2, 2021, at 7:25 AM, radioart at frontiernet.net wrote:
> 
> Does that NC110 BPF also maintain a 90 deg phase shift over that band pass?  I couldn't find any documentation on its phase response over the BP frequencies?  That was the magic of the CE audio filter network which made it superior to the B&W network and those of other companies.
> 
> I have had my 100V for almost 30 years now, rested it back in the early 90's and had to fix the BPF issue with the silver mica metal migration in the mid 90's.  I powered mine up a couple days ago and looked at my upper/lower sideband suppression and it was still over 50dB.  And yes, the audio BW was just shy of 4KHz as others have mentioned....  I get rave audio reports as I'm sure you all do too.
> 
> Regards, Dennis, k0eoo
> 
> 
> 
> -----Original Message-----
> From: central-electronics-bounces at mailman.qth.net 
> <central-electronics-bounces at mailman.qth.net> On Behalf Of Robert 
> Nickels
> Sent: Monday, March 01, 2021 6:37 PM
> To: Jim Candela <jcandela11 at outlook.com>; 
> central-electronics at mailman.qth.net; Kihwal Lee <kihwal at yahoo.com>
> Subject: Re: [Central-Electronics] 200V transmit bandwidth
> 
> On 3/1/2021 6:01 PM, Jim Candela wrote:
>> When someone says I am 4 Khz wide on SSB, or 8 Khz wide on AM, my 
>> reply is usually, Thanks OM!
> 
> Right you are, Jim,  some guys pay thousands of $$ for rigs to get that kind of response!     I'm happy with my 100V as it is but this looks like it could be a useful alternative for those who want to tailor the filter response:
> 
> https://www.ebay.com/itm/Norcomm-NC110-A-High-Stability-Audio-Band-Pas
> s-Filter-HF-Radio-800-3000Hz-NEW/201722397279
> 
> Google will produce a datasheet and there are posts on Repeater Builder about modifying the frequency response.  It's a nice small PCB that would easily fit inside the existing module if someone wanted to make it work, and the price is certainly right.
> 
> 73, Bob W9RAN
> 
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