[K2CC] New Equipment

Matt Krass mattkrass at gmail.com
Tue Nov 18 22:43:02 EST 2014


I see Greg is going for the passive approach. Is your solution an active one John? I would imagine a simple inverting unity gain opamp circuit might do the trick. Single ended in and out with a SPDT to switch the speaker from normal to opamp output. Can the human ear detect the slight delay on the altered signal? I'm used to dealing with ADCs and syncing these things up :)

KC2RGZ

P.S. If I were going to bother with opamps I'd probably add some adjustable gain voice band amplifiers in there for the fun of it to boost voice frequencies. 



> On Nov 18, 2014, at 10:35 PM, John Robinson <johnwesleyrobinson at gmail.com> wrote:
> 
> Greg's proposed circuit will also work even without the second set of transformers. I was originally picturing a very different circuit.
> 
> -John
> 
>> On Nov 18, 2014, at 9:01 PM, Greg Zenger <n2gz at gregzenger.com> wrote:
>> 
>> My thought process was that to do it passively, you would need a transformer on the input to separate the grounds (balancing the audio lines) I suppose there is no need for transformers on the output. 
>> 
>> Here is a sketch of what I am thinking.
>> 
>> http://oi61.tinypic.com/2wqcumv.jpg
>> 
>> I have never attempted to build this, but I'm pretty sure it will work if quality audio transformers are selected.
>> 
>> And then there are ways to do it actively as John pointed out.
>> 
>> Greg, N2GZ
>> 
>>> On Nov 18, 2014 7:37 PM, "John Robinson" <johnwesleyrobinson at gmail.com> wrote:
>>> Well here is some gory details on how to implement such a phase reversal circuit from one of the audio sites I frequently visit. http://sound.westhost.com/project107.htm . I do not see transformers working in a common ground scheme as the signal needs to be physically inverted in such a scheme as you would be driving the signal to  the ground of the other speaker most likely resulting in undesired results.
>>> 
>>> I may experiment one day with a variable phase circuit and see if it yields anything beyond a echo... It will probably be based on the Marantz vari-matrix circuit. This is what happens when you dabble in audio circuits for too long and vintage Marantz gear.
>>> 
>>> -John 
>>> 
>>>> On Nov 18, 2014, at 4:17 PM, Greg Zenger <n2gz at gregzenger.com> wrote:
>>>> 
>>>> You know what John, I thought about the whole roll-your-own breakout box idea for phase reversal switch and almost recommended such a thing in my previous email.  However most (maybe even all) headphones share a ground between the left and right channels which means such a breakout box approach would need audio transformers on both the input and output to re-derive the grounds prior to transmission over the common ground conductor in the headphone cable.
>>>> 
>>>> Greg N2GZ
>>>> 
>>>>> On Nov 18, 2014 3:03 PM, "John Robinson" <johnwesleyrobinson at gmail.com> wrote:
>>>>> I also highly recommend the linemaster clipper foot switch. They are well built, cast metal and made in the USA here in Woodstock, CT. I actually have one currently in front of me on a piece of medical equipment at work.
>>>>> 
>>>>> I modified a pair of headphones with a in/out of phase switch as Greg had mentioned. The pair I modified is a yamaha CM500 which are about 60$. They are a pretty decent pair and have plenty of room inside for the switch if you wish to add the feature. They also do not sound bad either and receive decent reviews. I suppose you could also roll a switch box which the headphones plug into and make any attached headphones in/out of phase without any physical mods to the headset.
>>>>> 
>>>>> For mic jack adapters i have picked up a couple W2ENY made adapters off ebay as I was often too lazy to roll my own. They work well and shipped from NY and support an ham in NY. Just a throwing it out there for another source I have used.
>>>>> 
>>>>> -John
>>>>> 
>>>>>> On Nov 17, 2014, at 10:53 PM, Ethan Miller - millere <millere at clarkson.edu> wrote:
>>>>>> 
>>>>>> The boom mic is in addition to the heil proset we already have. Good things to note on the other equipment, thanks!
>>>>>> 
>>>>>> - Ethan
>>>>>> 
>>>>>>> On Nov 17, 2014, at 22:45, Greg Zenger <n2gz at gregzenger.com> wrote:
>>>>>>> 
>>>>>>> I'll toss in my two cents here, if you dont mind.
>>>>>>> 
>>>>>>> The PR781 is a great microphone... however consider the environment of the
>>>>>>> station.. Im not sure of how things are setup now in the new station, but
>>>>>>> back in the late 2000's there was often a lot of 'spectators' hanging
>>>>>>> around the radio during contests. And by hanging around, I mean goofing off
>>>>>>> and being social. A big boom mike like that is likely to pickup alot of
>>>>>>> background noise. Not good.
>>>>>>> 
>>>>>>> I prefer to operate with a headset with a boom mic.  A headset helps put
>>>>>>> the sound inside your head; you can hear things that you cant hear
>>>>>>> otherwise when you are diggin' out that weak signal under all that splatter
>>>>>>> from the guy transmitting a few kc above or below. a headset with a phase
>>>>>>> reversal switch is nice. I use the Heil Pro Set Elite 6. Though keep in
>>>>>>> mind Its possible to do phase reversal on any headphones if get creative
>>>>>>> like K1JR did and build one into your favorite headphone.. A double pole
>>>>>>> double through switch installed to reverse the polarity of one of the
>>>>>>> speakers is all it takes.  The PowerSDR software might give an option to do
>>>>>>> it in software... I don't remember.
>>>>>>> 
>>>>>>> The club should definitely have an adapter like the HLS-AD-1-YM.... I bet
>>>>>>> you could build one using parts found around the shack.
>>>>>>> 
>>>>>>> This year we used both an external speaker for spectators to listen, and
>>>>>>> had the Heil Pro Set Elite 6 for the operator... it worked well.  Going
>>>>>>> forward, I think it might be nice to have a multi channel headphone amp to
>>>>>>> allow additional headphones to be plugged in with independent volume
>>>>>>> control.
>>>>>>> 
>>>>>>> I do not recommend the Heil foot switch... I bought one once and it felt
>>>>>>> cheap and I just didnt like it... Save up and get a a Clipper... (model
>>>>>>> 632-SC3)  Here is a decent deal.... though ive seen them cheaper at
>>>>>>> hamfests:  http://ebay.to/1AaqcM3  Its cheaper than the Heil, and anyone
>>>>>>> can figure out how to wire it in.  Put an RCA connector on it and plug it
>>>>>>> into the back of the F3K.
>>>>>>> 
>>>>>>> Best of luck and 73
>>>>>>> 
>>>>>>> Greg N2GZ
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> On Mon, Nov 17, 2014 at 9:03 PM, James P. Dapp - dappjp <dappjp at clarkson.edu
>>>>>>>> wrote:
>>>>>>> 
>>>>>>>> Hey all, some of our equipment broke this weekend and we are looking to
>>>>>>>> buy some new gear. As for the microphone, here are a few to consider:
>>>>>>>> 
>>>>>>>> http://cart.flexradio.com/Heil-PR781-Balanced-Microphone_p_21.html
>>>>>>>> http://cart.flexradio.com/Heil-HB-1-Microphone-Boom_p_837.html
>>>>>>>> http://cart.flexradio.com/Heil-FS-2-Dual-Foot-Switch_p_836.html
>>>>>>>> http://www.dxengineering.com/parts/hls-ad-1-ym
>>>>>>>> 
>>>>>>>> 
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