[TenTec] 565 Low level audio on headphones

[Kim Elmore]

Hi Bob,

Well, I "gots to know:" where did you get those?

73,

Kim N5OP

At 10:06 PM 3/15/2013, you wrote:
>As Jim K9YC said earlier, it is normal or typical for designers to 
>put some value of series R between the audio output device and the 
>HP connectors. This will prevent shorting of the device should some 
>inadvertent event take place like a shorted HP cord, bad connection or such.
>
>Now with the series resistors then add the HP impedance to ground 
>and one has a voltage divider.  The larger the series resistor 
>values and the lower the HP impedance the less voltage across the 
>headphones.  It's an Ohm Law thing.  The idea is to have a series R 
>of such value that shorting the HP connection to ground will not 
>cause destruction of the headphone amp device. In general, higher 
>impedance headphones i.e. 30 to 65 ohms, should perform better, 
>again depending on the actual sensitivity of the headphones than 
>those headphones of lower impedance values.  Yet impedance is not 
>related to headphone sensitivity, so two factors must be 
>considered.  Thus headphones of lower impedance should by choice 
>have a higher sensitivity while headphones of higher impedance can 
>have lower sensitivity values.
>
>I recently heard a station with quite good sounding audio and 
>inquired as to his radio and mike being used.  He was using a 
>headset with boom mike.  He provided me the information and I 
>ordered the item.  It has the numbers SM-750M.V and the name Stereo 
>Dynamic Headphones on the band.  Nowhere does it say "Made in 
>xxxxx"  you fill in the blank.   The item was delivered by postal 
>service with a total cost for the merchandise and shipping in the 
>amount of $5.95.  Yep, complete to my door for a total of $5.95.   I 
>find the headphones work very nicely and sound quite good and are 
>moderately comfortable and even the in-line volume control 
>works.  The boom mike has a nice wind screen and when connected to 
>the Omni VII gets great audio reports.  Mechanically and 
>structurally, I view the $5.95 purchase is a bit more than a piece 
>of junk.  If it didn't work it would be total junk.  I would expect 
>parts to fly around the room should I drop the headphones on the 
>floor.  I've never seen the likes of molded plastic snapped 
>together. This goes to show that one doesn't have to spend a hundred 
>bucks or so for a name-brand headset that works.
>
>73
>Bob, K4TAX
>
>
>
>
>----- Original Message ----- From: "Richards" <jruing at ameritech.net>
>To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
>Sent: Friday, March 15, 2013 9:10 PM
>Subject: Re: [TenTec] 565 Low level audio on headphones
>
>
>>Er...so, what DO the engineers at TT say about this?   Have you asked them?
>>
>>I know loads of guys who swear by the CM500 on the Orion and Orion II
>>and other TT rigs.  If you suffer low receiver volume, I suspect 
>>something is fundamentally wrong with the radio.   Jim Brown is a 
>>big fan of the CM500 - and he is serious about audio.  If it did 
>>not perform well, he would have said so.
>>
>>I suspect there is something fundamentally wrong with the rig, and 
>>adding a band aid resistor is not an appropriate remedy - it might 
>>cover for a larger problem, but I doubt that is the best course.
>>
>>Trust your instincts...  discover the real problem.   When this 
>>happens to me, I ask the local rabble for help in diagnosing it - 
>>and they have always helped me find the real root problem, bless 
>>their pea-picking hearts !
>>
>>Just my take.
>>
>>-------------------------  K8JHR  ----------------------------
>>
>>
>>
>>On 3/15/2013 6:00 PM, Paul K. wrote:
>>
>>>So, now I am considering looking at the resistor change.  Although, I am
>>>still seeking additional advice and suggestions. I hate second guessing
>>>the engineers at Ten Tec.
>>
>>________________________________________________________________
>>
>>
>>
>>.
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>
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