President Washington and Dwight D AM power potentiometers?!?

[DeadEcho]

Hello!

My friend recently bought a Uniden President Washington base and President Dwight D base station off eBay but they only do 1 watt and I was looking to bring them back up to 4 watts. I did some googling but I cannot seem to find a definitive answer to which petentiometers I need to turn to bring the AM carriers back to 4 watts on both radios. I was hoping some kind soul would set me straight on which potentiometers i need to turn to bring those carriers back up.

Thanks in advance!

 

[Robb]

Do you know which PLL chips are in each radio?
858, 8719, or 2816?

The reason I ask is that these radios all have variable resistors on the board to adjust the dead key watt levels; but they all vary depending on the main board used. That PLL chip determines which board they have.

 

[DeadEcho]

I do not know what PLL chips he has because I have yet to see the radios in person and he isn't very tech savvy.

 

[nomadradio]

It's an AM-only model, made with more than one circuit board.

Identifying the PLL chip found in the radio serves to pin down which actual circuit board yours was built with. The original 1978 radio has a fat 28-pin PLL chip type uPD858, marked "D858" on the chip.

The later version used a physically-smaller 22-pin PLL integrated circuit marked uPD2816. Will have "D2816" printed on it.

Any specific advice starts with knowing what is inside the radio. The different circuit-board versions place the important parts in different places inside.

Like asking how to fix a bad fuel pump in your car without revealing which motor or model year.

That radio does not have a built-in way to adjust the carrier power. It's built to run with a 4 Watt carrier. Optimizing a tuneable coil at the final power amplifier can increase this somewhat, but not a lot. Could be that someone has simply cranked one or more adjustments away from the proper "peak" power setting.

It's possible that someone has modified it to reduce the carrier. Removing a jumper wire and putting a parallel-paired resistor/electrolytic capacitor in its place is a popular method. But the various versions of the radio have different printed-circuit boards. And that's the key to any specific suggestions, since this determines where the parts would be added for that modification.

Have you removed the cover and looked inside yet?

73

 

[nomadradio]

Oops. Forgot you also mentioned a "Washington".

That one is a SSB radio, or should I say two different SSB radios. The original 1978 radio has a 4-pin mike socket. The later version has a 5-pin socket.

Both Washington radios have a trimmer pot to set the AM carrier level. And each one is in a different spot inside.

73