Collins 390 mute function

[iw5ci]

I would like to mute the 390 receiver automatically when trasmitting instead of putting it manually in stand-by.
As supposed i have to' ground the break in terminal while the break in switch is on. Well it doesn't work !
What i am missing ?

[n2bc]

Not sure if you have an R-390 or R-390A.    On the R-390A (and I would guess the non-A) the mute function is sort of 'upside down'.... 

For the R-390A set the front panel to BREAK IN ON (S103) then ground TB03-9 (BRK IN) to enable the RX - open TB03-9 when transmitting.   FYI, TB03-9 is 6.3VAC (filament voltage).   

[iw5ci]

mh.. the break in switch does not work... if i turn bkin switch on without grounding bkin pin in the back i still have the radio operative, also if i ground the bkin pin i have audio in either bkin switch on and off... i have a 390.
What do you suggest to check?

[N8ETQ]

   You should hear the "Antenna" relay click when turning the
function Sw from "Standby" to "AGC", and again from "MGC" to
"CAL". there is also a "mute" relay in there you should hear
when switching to "SQUELCH".  CR801 provides power for BOTH
relays.

GL
/Dan

[iw5ci]

Hi Dan, for shure i can ear the mute relay click when squelch is opened or closed (it's a loud relay).
I cannot ear the click when switching between stby and agc maybe the relay is more silent. This evening i will check.

My trasmitter when in TX mode short circuit automatically the Receiver antenna, do you think is sufficient to avoid damages to the RX frontend? (the received signal in the s-meter of the 390 when the tx is operated is less that some big BC stations) or it is necessary to switch the 390 in mute?

[iw5ci]

I have tested the relays. I can ear a click when i switch from off to stand by. No more clic from stand by to agc or from Mgc to cal . I ear a louder relay when squelch is engaged .
What do you think about?!

[N8ETQ]

   Well the Antenna relay is hung up for sure. The manual is online at


http://www.jamminpower.com/main/r390.html

Mine is a 1952 Motorola.

  Please keep us posted. 

GL

/Dan

[The Slab Bacon]

Just my $.02 worth.......................

390s and 390As have a small selenium rectifier usually nounted to the rear of the cabinet. It provides the DC for the antenna relay by rectifying the 24vac filament line. These things are notorious for crapping out. Sometimes even going up in smoke on the way. Simply replace it with some 1N4XXX diodes and you should be good to go.

                                                       The Slab Bacon

[iw5ci]

Thanks, can you show me where is the selenium rectifier ?
but if the rectifier is blown why i ear the click of the relay when i power the radio?
if the antenna relay does not work which consequences cause to the operations of the radio?

[N8ETQ]

   It's on the bottom of the P.Sup chassis acording to the pix
on page 60 of TM 11-856 but I think your right, it powers BOTH
relays, but still worth checking. 

Again, The manual is online at


http://www.jamminpower.com/main/r390.html

   A bunch of "R-390" and R-390A manuals in any format you want.

GL
/Dan

[ke7trp]

I had a real fight with my R390 trying to get the breakin to work.  No matter what, It would not mute. I spent a day trying to figure out why.  In the end, I used a 12 volt wall wart, ran that to a relay and the other side "through" the antenna relay contacts on the R390.  When I key the T368, The relay latches and powers up the mute in the R390 which then mutes it. Its two wires clipped onto the r390 relay with aligators so it was no modification.  My diode/rectumfire was good. Still no volts. I ripped all the units out and never did figure out why.  I suspected that the relay on the PS board was not latching the antenna relay on due to bad contacts. Since I did not have another one of these sealed relays, I used the wallwart PS.   

This works FB and has for a year.

C

[iw5ci]

Hi, i have done dome tests and i found that from ground to Break in contact on the rear panel i read about 12v AC when bkin in switched on and 0v when off.... what do you think?

[ke7trp]

Try to power up the relay with an external source and see if it clicks. Its possible you have a bad antenna relay

[iw5ci]

Hi the relay coil is ok but as i can see there is no voltate to' the ant relay when stby in engaged. Where to start from?

[ke7trp]

This is exactly how mine was.  Flip the Radio over, Remove the Power supply, Its easy. A few screws and check it out.

I fear you have the same trouble as mine.. The Relay on the power supply. Its a sealed relay and cant really be serviced. Some have cut the can off it with a hack saw, Cleaned and repaired it and then put it back in the rig. For me, An exernal 12 volt wall wart and a cheap 12volt relay was the easy solution. 

C

[iw5ci]

Can you explain in simple word now you

 the relay ?! So now you have mute again?

[ke7trp]

There is a relay that sends power to the Antenna relay.   That relay is likely bad in your radio.


Here is what I did:

My T3 has a set of MUTE contacs that are normaly open.  I suspect that your transmitter does also.

I took a 12 volt wall wart..  1 amp unit.
I put the neg lead to the antenna relay in the R390 (one side, does not matter which side) with a clip lead.
I put the other lead of the 12 volt wall wart to the Normaly open contact on the transmitter.

This way, When I key the transmitter, The transmitter relay closes and sends 12 volts to the r390 antenna relay.  This works great.  If you want total mute, Run one side of the Speaker lead through another set of normaly CLOSED contacts on your transmitter or dowkey. This way, It cuts the speaker wire off when you key.

C