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@ameritech.net>
To: "Discussion of Ten-Tec Equipment" <tentec@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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