Amplifier transistor matching?

they also make the SKP100G2 which should be cheaper (no phantom power), but it is new and not yet in the catalogue. The existing receiver should work with these too.

--
ciao Ban
Bordighera, Italy

I also have made this experience. Both BJT and FETs go short-circuit and blow the mains fuse. Maybe in a bridged output configuration it could be a DC-value, but then the protection kicks in and disconnects the relays.

--
ciao Ban
Bordighera, Italy

Cor, I too have one of these. Is yours a made in California real Marantz or a later one made in Japan. I have a scratchy right channel. I've cleaned the pots, especially the volume pot, but it doesn't seem to have helped. Have you had this problem? If so what did you do to rectify it? John

My bad. Mine is a Japan model. I have it pulled out as I'm rearranging the office. In small print under Marantz Sun Valley USA is made in Japan. This clears up the incongruity as I thought this series was long after his USA run.

That looks good, although possibly a little chunky to put in one's pocket !

is new and not yet in the

I also found this one sold as a 'kit' with a clip on mic - but it's back to 9V batteries.

Graham

...

Five hours??? In CHURCH????!?!?!?!?!?!?!!! =:-O

--
Cheers!
Rich
 ------
 "Hear about... the fellow who was descended from a long line his mother
  heard?"

9V batteries.

Uh, stupid questions department here - why not just use that one?

Thanks, Rich

I've seen failures where the initial failure was probably a short, but the resulting current fused the leads of the device (TO220) causing an open. In gear that has a fuse on the mains but not on the power supply, there's plenty of juice in the filter capacitors to turn a TO220 into melted bits without tripping the mains fuse.

Many years ago I bought a bass amp in which the emitter resistor of one side of the push/pull output had gone open, with the transistors still intact - not sure how. Got a great deal on the amp from the seller, who assumed it was totaled. One resistor later, I had a fine amp that I used for a couple of years and eventually sold at a profit.

But I agree, it's unusual.

Hello Graham,

They are seven cell so it is slightly above 9V. Of course it will drop to 8.4V rapidly but then they stay there almost until exhaustion. Alkalines show a more steep voltage decline. You can use them down to 6V and below but the mike's circuitry won't work properly when they are this low. That is one reason why we changed to NiMH. The other was cost as 9V alkalines are really expensive. They rarely go on sale like AA batteries sometimes do.

Regards, Joerg

Hello Ban,

Thanks! This could even work with our existing bank of UHF diversity receivers. I'll have to find out whether they would operate on NiMH at

2.4V. But even if not, AA batteries are cheap except that this leaves the environmental concern of disposal.

Regards, Joerg

Hello Graham,

batteries.

I really want to discourage our church to buy any more 9V gear. It just doesn't hold up well enough. But Ban's hint regarding the handheld is great, too, because we also use handhelds and have the same issues there (battery quits or just fails). Also, Sennheiser should have no problem designing a similar transmitter for lapel use. I mean, it's not rocket science. I have built transmitters that worked off 2.4V decades ago. They could run for days.

Regards, Joerg

Hello Rich,

Because that one was for ham radio and the stuff for secondary user UHF needs FCC blessing.

Regards, Joerg

Hello Rich,

No worries, our sermons aren't that long. But 1st service, education hour (actually more than an hour) and 2nd service total about five hours. All back-to-back with little time to swap batteries. How our pastor manages that marathon, I don't know. It must be pretty tough.

Regards, Joerg

only

The guys in aapls mention that big live shows buy 9V alkakines by the case from direct distribution. That makes it rather less costly.

Regds, Graham

Hello Graham,

conversion cable

That is a bit bulky. But it still gives hope that they'd come out with a

2.4V lapel wireless some day. The electronics in there can't be this big.

Regards, Joerg

9V batteries.

I just checked the full datasheet for this one - the 'transmitter module' and it says nominal battery voltage 2.4V ! Good for 8 hrs they say.

Trouble is, it measures 4" x 1-3/4 " sq. Only has an XLR input so you'd need a conversion cable from your lapel mic.

Graham

I've heard US contributors to the audio groups mention 'Caig' as good for switches - maybe pots too.

I have no expereince of it though as it doesn't appear to be sold in the UK.

Graham

TO-220s ! Those are driver transistors ! ;-)

It was a film resistor that failed rather than wire wound I assume ?

Yup, Graham

Mine is made in Japan. Ser 27960. Maybe that it why the manual I got does not exactly match the components I have.

My pots seem to be ok. I only noticed that the on button is slow in the way out.

Are you sure its the pots? If you switch sides at the preamp plugins does the scratchiness switch sides?