[Johnson] T/R relay

[Charles Ring]

On 7/10/2013 2326, Bill Cromwell wrote:
> On 07/10/2013 11:00 PM, Charles Ring wrote:
>> I have used the 250-39 Johnson T/R switch since 1967. I've had 3 of 
>> them and the power transformer on two of those have failed. Since 
>> returning to the air a year ago I've been using one with my Globe 
>> King 500A and Drake R-4C.  It works, but unlike long ago, I can't get 
>> full QSK. The receiver is being badly desensed. I don't remember if 
>> it did better then with the R-4C or if that was only with the 2-C and 
>> the R-4B, both of which are waiting for repairs. I am interested in 
>> changing to either a fast relay or a PIN diode switch. I seldom do 
>> faster than 25WPM.
>>
>> 73 de W3NU
> Hi Charles,
>
> My Johnson Ranger has an issue with a reduced but still present plate 
> current flowing with the key up. Using the Johnson T-R switch I can 
> hear the "diode noise" in the receiver. Right now I suspect a wiring 
> change sometime in the past or a defective part allowing that plate 
> current. I have been piecemeal reworking/refurbing the Ranger. The 
> manual says there should be no plate current with the key up in the CW 
> mode but there is. Up to me to find out why. I am using the open frame 
> relay with the Ranger until I resolve that issue - and no QSK.
>
> Is your TX final amp cutoff with the key up? One possible source of 
> your trouble.
>
> 73,
>
> Bill  KU8H
>

Nothing shows on the meter. I do sometimes get some diode noise but 
that's a separate thing. When I key the transmitter the R-4C is so 
desensed that I do not hear myself in the receiver (unless I detune the 
preselector some) and have to rely on keyer sidetone. It recovers but 
not fast enough for real QSK.

-- 
*Charles Ring W3NU*