[TenTec] Fwd: Model 715 question

[Richards]

Thanks, Barry.

Yes ... however, if I understand your suggestion, that will not supply 
the required bias voltage, just provide a connector for it - I still 
need a source for that voltage.   (Sorry if I missed something in your 
post.)

	I think I have two options...

1)  Replace the existing panel jack, and draw the required 2.5-5 volts 
bias voltage from the existing circuit  (perhaps borrowing it from Pin 
2 on the 8-pin connector.     I could probably wire that up, but I do 
not know if that would cause any problems in the circuit I cannot, with 
my more limited knowledge of circuits, foresee.   While I know it would 
power the microphone, I don't know what adding 5 volts to the jack tip 
line would do to the rest of the circuit.

	(Note... that would provide 10 volts according to TT
	specifications,  	and I would probably not only draw
	the voltage from there, but also step it down by half.
	These computer microphones only "like" 2.5  to 5 volts
	bias voltage typically.

Or

2)  Use an external battery box that provides bias voltage for this type 
of thing.   AndreaElectronics makes one, and I think there is one either 
included with or available for the Yamaha set.   I have some older ones 
in the parts box,  left over from some older AudioTechnica and 
RadioShack lavalier microphones.   I could easily make such a battery 
box, I suppose, if I could figure out a schematic for one.   It cannot 
be too difficult to apply 5 volts to the sleeve on the plug to energize 
the mic capsule ?

http://andreaelectronics.com/Buy/ProductDesc/APS100.htm

Comment --

I am just plain surprised (and obviously disappointed) to discover 
TenTec put a MONO jack for a DYNAMIC type microphone, instead of the now 
ubiquitous and pervasive (i.e.. MORE COMMON)  electret type computer 
headset.

TenTec said the jack was intended for the "popular" headsets, like HEIL 
sells... But, while HEIL does sell dynamic microphones, but I cannot 
recall ANY of its cables terminating in a MONO 1/8 inch plug.   I had 
blithely assumed TT  had provided a three-pole STEREO jack, to 
accommodate what IS the more common electret condenser type computer 
headsets,  like the truly popular Yamaha CM-500, and others like it.   A 
1/8 inch MONO plug for a dynamic mic is hardly the common trend, and not 
found on popular headsets.

I plugged in an old Shure HW-501 dynamic head worn microphone (mic, but 
no earphone receivers)  which terminates in a nice old fashioned 
two-pole 1/8 inch phone plug  -- and it sounds buttery smooth on the 
circuit ....   but this is hardly a COMMON arrangement as TT claims.

I am supplying Koss SB-45 headsets to the contest station instead of the 
Yamaha model.  No offense and no complaint with the Yamaha set, but the 
Koss models are $20 cheaper and sound just as good.   Oddly enough the 
Koss SB-40 looks just like the Yamaha CM-500, bu the Yamaha model now 
uses an electret condenser mic capsule, while the Koss model still uses 
a dynamic capsule.   That would work swell on the Model 715, but dynamic 
computer headset microphone capsules are certainly the exception these 
days.


----------------
Happy Trails.
=======================  Richards / K8JHR  =========================

On 5/26/2011 12:21 PM, Barry N1EU wrote:
> I would just buy a plug that mates with the 715 front panel mic jack
> and wire it to a stereo 1/8 in jack to plug the CM-500 into so your
> mic audio and bias are handled like on the K3 rear panel jack that
> you're familiar with.
>