[Elecraft] 40M Tx Alignment Hi Current Concerns

[Gil Stacy]

Don,

The power source may have been part of the problem..  I had been using a 2.9AH gel cell (12.4 volt charge) and a power cord that came with an SWL 40 kit.  I just hooked up a RS 13.8 3A power supply with some power cord from RS for DC use.  Paired cord with postive marked with white stripe.   May not have been quite 18 guage, but close.  With power up to the radio, rx on, the power supply at the connectors read 13.78 volts with a DVM.  At the LCD on the radio, the voltage was 13.1 with the RX on at 7100.  With a setting of 5 watts on receive, the LC D read 13.1 with a drain of .22.  The DVM read 13.78.   In TUNE mode, the first time I tested, the voltage dropped to 12.4 with a drain of 1.4 amps. Happy dance.  Ten minutes later, 1.8 drain.  DVM read 13.69 or a drop of 0.09 at the connectors.    The set had been turned off.  On 10 watts, LCD read 13.1 voltage, with a drain of .22.  DVM read 13.78 at the connectors.  In TUNE mode, voltage drop on LCD read 12.2 with a drain of 2.4 amps.  DVM at the connectors showed 13.65 or a DVM drop of .13 volts.  Would it still be the power cord??  I can always cut some lamp cord when no one is looking. Thanks
73/Gil






>From: "Don Brown" 


>To: "Gil Stacy" 
,
 

>Subject: Re: [Elecraft] 40M Tx Alignment Hi Current Concerns 

>Date: Sun, 12 Jan 2003 14:23:48 -0600 

> 

>Hi 

> 

>Sounds like your power supply is dropping out. With the supply voltage down 

>to 10.8 volts the current will be high. The power supply should be steady at 

>13.8 to 14 volts. Some of the basic power supplies do not regulate very 

>well. 

> 

>Another problem could be voltage drop in the power cable. Check the power 

>supply with a voltmeter at the supply terminals and hit tune. The supply 

>voltage should not change. The supply cable needs to be 18 or 20 gage wire 

>to keep the drop down. 

> 

>Don Brown 

>KD5NDB 

> 

>----- Original Message ----- 

>From: "Gil Stacy" 


>To: 


>Sent: Sunday, January 12, 2003 1:40 PM 

>Subject: [Elecraft] 40M Tx Alignment Hi Current Concerns 

> 

> 

> > 

> > 

> > 

> > I am attempting the 40M Transmitter alignment in K2 #3104 and have high 

>current concerns. With the power dial set at 2.0 watts, in TUNE mode, I 

>peaked L1 and L2 to 3.6 a max of 3.6 watts. 

> > I set the power dial to 5 watts, entered TUNE mode, and had a voltage drop 

>from 11.7 V to 10.8 with a current drain increase from .22 to 2.14 amps. 

>Recommended amps in TUNE mode are 1.3-1.6 amps. 

> > At 10 watts in TUNE mode, the voltage drop is 1 volt with a current drain 

>from .22 to 2.5 amps. Reommended amps in TUNE mode are 1.8-2.0 amps. 

> > Voltage checks, recommended value in parenthesis where differs from 

>actual reading. 

> > Q6 B ok, C 10.8 (13.3), E .27 (.4) 

> > Q7 B ok, C 11.16 (13.4), E ok 

> > Q10 S 1.5 (1.6), G ok, D 1.5 (1.6) 

> > Q11 all ok 

> > 

> > Q13 E ok, B ok, C 6.1 (7.5) 

> > Q20 S ok, G ok, D 31mv (0.0) 

> > Q24 G ok, S .81 (1.2), D .87 (1.3) 

> > U9 1 ok, 2 4.8 (6.9), 3 5.02 (6.9), 4 31mv (0.0), 5 35mv 

>(0.0) , 6 5.3 (6.9), 7 10.5 (13.8) 

> > U10 ok 

> > Q5 is untested as I have not pulled off the heat sink.Comments and 

>suggestions would be appreciated. Thanks. 

> > Gil KG4VCG 




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