Batboard

I'm trying to get an old-but-was-supposedly-working
consolette to run a VHF Mitrek. It worked when first
connected but is now not transmitting and also not
making any receive noise. I suspect the power supply
because it's showing 22 volts at the PS output to the
radio side and it should be around 13/14VDC. I might
have had the pass transistor(s) go bad. It's also
showing 22VDC at the transmit lamp when I hit the
PTT.

Anyway, I need to know if I'm pointed in the right
direction, and also if someone might have one of these
boatanchor power supplies I can buy.

I know I could just hook in a 20 Amp Astron supply
but the whole idea was to unkluge the Mitrek setup as it
sat on the bench, what with the control head, separate
speaker, etc.

All advice greatly appreciated.

Tom,

You do likely have shorted pass transistors.

I would suggest starting there.

The pass transistors are still available and are no problem to change.

As for the remainder of the radio, you really need a manual and hopefully your radio has not sustained any other damage.

The real question is, what is the power out rating of the radio? Did you start with a 100 watt drawer or did you remove a lower power drawer and replace it with a 100 watt drawer and now you melted the power supply?

If you wiped out lots of stuff in the drawer, I would pull your channel elements and replace the entire drawer rather than fix it as it's far more cost and time effective.

George

George,

Thanks for confirming my thoughts about the pass transistors.

No, I'm just running low-power radios in the drawer. Before the
thing quit I measured 35 watts out on 146.52 mHz.

I think I'll patch in my 20 amp. Astron at the bottom power block
and see if that gets the radio running again, assuming I haven't
fried it with the 22 volts!

Regards,

Blown power supply in a Consolette, very common. The pass transistors do not hold up too well to shorts or long duty cycles.

There were two basic supplies used with Mocom 70, Syntor, and Mitrek chassis, the 7 or so Amp with one pass transistor, and a 15 amp ICAS with two pass transistors in parralel. They all run over 14 volts out, even as high as 14.8 volts from the factory.

Also,I have seen consoletts offshore that had 25 volts on them for a week before a tech could get there...never saw any damage! Repaired the PS and all worked fine.The Mitrek is one of the most "bullet proof" radios ever made by Motorola.
mod

That is why every Consolet in service with us has had the power supply replaced with a Duracom switcher fitted in the same space.

NO more failures....


The remote 110 watt low band Mitrek Con, has the PS outboard. That one has a 30 amp PS.

Duracom switcher was my cure as well!Who cares if I cannot get 150 watts on lowband at 15 volts if I can get rated 110 on 13.8!
mod

n5tbu wrote:Duracom switcher was my cure as well!Who cares if I cannot get 150 watts on lowband at 15 volts if I can get rated 110 on 13.8!
mod

But they surely WILL notice the difference... no more total failure due to the power supply!!


I used the DPS 15 power supply internally for most Consoletes and the DPS 30 for the 110 watt stations.
http://www.duracomm.com/06DPSps.pdf

Other Duracomm Power Supplies that can replace the Consolete OEM's:

http://www.duracomm.com/powerblocpowersupplies.htm