Telsat 925 Receive(d)

[BBB]

Picked up this nice looking Lafayette Telsat 925. I don't have a mic yet. I plugged it in and the clock runs and all other lights work. Are these rare?

I can't get it to receive any signal and output to the speaker. When I turn the CB squelch up I get a slight "thump" like the speaker is picking up the squelch engaging.

Since this radio does have a relay I shouldn't have to have a mic hooked up for it to output to the speaker? There is no external speaker jack on the back. I'll try manually bypassing the speaker and cleaning the relay.

Another thing is I can't find this crazy mic connector anywhere. The pins are configured in a "Y"

Mic wiring from Bell's:

Audio pin 1
Ground pin 2
Common pin 3
PTT pin 4
Receive N/C

[cbrown]

Nice looking rig!

For a microphone plug, give Ken a call. He used to have them. Part # CBC4Y.

www.kenselectronics.com/

The rig is relay controlled, but some of them required a jumper between pins 2 & 3 (ground & shield).

Look at the connector on the radio. Bottom connector is Pin 1. Connector in the middle is Pin 4. Connector on the left is Pin 2 and connector on the right is Pin 3. That is the way they used to be numbered.

Based on the above, the bottom pin (1) is your TX, the middle pin (4) is your audio, the left one (2) is your ground and the right one (3) is your shield.

["Doc"Hammer]

Here you go, Sparky...
www.ebay.com/itm/vintage-tube-radio-4-pin-microphone-plug-and-panel-jack-/300855614401?pt=US_Radio_Comm_Microphones&hash=item460c645bc1

[BBB]

Thanks for the replies ;D Isn't that one of the funkiest mic connectors?

Okay, I woke up the receive by plugging in (and out) a headphone into the 1/4" jack in the front of the radio. The speaker audio circuit must run thru that jack's contacts and it must have been dirty causing the no audio on the receive. It has a good receiver! Now to jam a mic on there...

[BBB]

Are these all that rare? Not finding much on them other than it's in Sams #62

[BBB]

Put the mic to it and found out it won't transmit on 2,6,10,14,18 and 22

Otherwise reported "sounds good like a radio should" after adjusting the mic gain VR13. Not a major swinger at 4.5 DK with a 8.5 watt peak on the Hy-gain meter.

Now to find out what caused the drop out of certain frequencies. Probably one of the mixing crystals, but jeeze which one...

The priority channel monitor lights up every time there's activity on 9, but a simple yank of the socketed stand alone crystal fixes that. It does not appear to have any bearing on the lack of transmit on those "other" channels.

The priority channel crystal must be mixed with another one to achieve receive of CH9 because it's labeled 27.500 ? Be kinda cool to figure out what the formula is to swap in another crystal to monitor another channel other than 9 since it doesn't say "CH 9 Monitor" on the faceplate anywhere.

[Sandbagger]

Feb 8, 2013 13:40:03 GMT -5 BBB said:

Put the mic to it and found out it won't transmit on 2,6,10,14,18 and 22

Otherwise reported "sounds good like a radio should" after adjusting the mic gain VR13. Not a major swinger at 4.5 DK with a 8.5 watt peak on the Hy-gain meter.

Now to find out what caused the drop out of certain frequencies. Probably one of the mixing crystals, but jeeze which one...

The priority channel monitor lights up every time there's activity on 9, but a simple yank of the socketed stand alone crystal fixes that. It does not appear to have any bearing on the lack of transmit on those "other" channels.

The priority channel crystal must be mixed with another one to achieve receive of CH9 because it's labeled 27.500 ? Be kinda cool to figure out what the formula is to swap in another crystal to monitor another channel other than 9 since it doesn't say "CH 9 Monitor" on the faceplate anywhere.

Yes, the problem is a single crystal, in a group of 4. If that radio has the 23 and 14 Mhz crystals it'll be one of the 14's, most likely the second lowest frequency.

As for the channel 9 monitor, it should be a simple single conversion, and a crystal running at 27.500 would give you 27.045, or channel 7A. hmmm....... I wonder if the previous owner wanted to monitor that RC channel for some reason.....

[Sandbagger]

Feb 8, 2013 15:09:57 GMT -5 Sandbagger said:

Feb 8, 2013 13:40:03 GMT -5 BBB said:

Put the mic to it and found out it won't transmit on 2,6,10,14,18 and 22

Otherwise reported "sounds good like a radio should" after adjusting the mic gain VR13. Not a major swinger at 4.5 DK with a 8.5 watt peak on the Hy-gain meter.

Now to find out what caused the drop out of certain frequencies. Probably one of the mixing crystals, but jeeze which one...

The priority channel monitor lights up every time there's activity on 9, but a simple yank of the socketed stand alone crystal fixes that. It does not appear to have any bearing on the lack of transmit on those "other" channels.

The priority channel crystal must be mixed with another one to achieve receive of CH9 because it's labeled 27.500 ? Be kinda cool to figure out what the formula is to swap in another crystal to monitor another channel other than 9 since it doesn't say "CH 9 Monitor" on the faceplate anywhere.

Yes, the problem is a single crystal, in a group of 4. If that radio has the 23 and 14 Mhz crystals it'll be one of the 14's, most likely the second lowest frequency.

As for the channel 9 monitor, it should be a simple single conversion, and a crystal running at 27.500 would give you 27.045, or channel 7A. hmmm....... I wonder if the previous owner wanted to monitor that RC channel for some reason.....

Well, as luck would have it, I have SAMS #62, and the crystal that you need to replace is a 10.625. and that 27.500 crystal is the correct one for channel 9. The I.F. in the monitor receiver is 435 Khz, not the usual 455 khz, so you take 27.500, and subtract .435 and you end up with 27.065.

[BBB]

Thank you Sandbagger for the info.

I'll see if I have a 10.625 crystal in a donor rig. The main crystals in the Telsat 925 are nested on a sister board behind the channel selector switch.