[TMC] VOX/PMO?

[Roy Morgan]

On Oct 8, 2009, at 10:13 PM, W2HX wrote:

> Hi there. I am looking to put together a TMC station using a GPR-90  
> and
> SBE-2 or -3 and PAL-350.

Do you HAVE a PAL-350?  I do, but no power supply.. BIG PROBLEM!   
Building a replacement for the missing PAL supply is a complicated  
job:  change of voltages for different modes (CW - SSB) are done in  
the supply.  All protection, overcurrent cutouts are in the supply.   
(Metering is in the PAL).

> I understand that the SBE requires a frequency source.

The SBE has place for (about) 10 crystals, so if you are doing fixed  
frequency things, like AM on 3885, or TTY on commonly used  
frequencies, no problem.. IF you have the right crystal.

> Can either a VOX or
> PMO satisfy this requirement?

Here I depart from being sure: I think either one would work, however,  
the PMO is meant for "portable" use and (I THINK) does not have the  
frequency multiplier stages that the VOX has, see below (I looked at  
the manuals).

The VOX has:
- A BFO oscillator with two selectable crystal sockets (455 kc typical)
- A master oscillator operating from 2 to 4  mc
- Provision for three selectable crystals (operating 2 - 4 mc four  
output to 64 mc)
- mulitplier stages for output from 2 to 64 mc.
- a 100 kc crystal calibration oscillator
- is rack mounted

THE PMO has
- no BFO oscillator
- oscillator operating from 2 - 4 mc and unit output from 2 to 8 mc
- 100 kc calibration oscillator
- is "portable" but could be rack mounted.

> Or is one preferable over the other?

Yes, for use with transmitter, get a  VOX.

If I remember correctly, the PAL 350 must be fed the frequency you  
want to get out of it.. it does not multiply up from the 2 - 4 mc  
range (as does the GPT-750)

Roy

Roy Morgan
k1lky at earthlink.net
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Groton NY, 13073
Home: 607-898-3607
Cell: 301-928-7794