Fw: [Drake] TR-7 - Part two

[pfizenmayer]

----- Original Message ----- 
From: "pfizenmayer" <pfizenmayer at qwest.net>
To: "GGLL" <nagato at arnet.com.ar>
Sent: Wednesday, December 03, 2008 7:29 PM
Subject: Re: [Drake] TR-7 - Part two


> The classic reason for low output on ten meters is failure of one or both 
> of
> the MPN3404 calibrator diodes CR1401 and CR1402 which are on the high pass
> filt a little hard to get to but can be done without too much pain.  Then
> next the R/T pin diodes can have a failure  CR1501,CR1502,CR1503 which are
> UM9401 pin diodes. I was able to get both types from RF Parts a couple 
> years
> ago - dunno if they still have them.
>
> 9) Check MPN3404/1S2186/1SS135 CR1401, CR1402 calibrator diodes on the 
> high pass filter assembly front. Checks can be done with an ohm meter or 
> by signal check. To do signal check, inject a 0.5 micro volt signal on 
> 7309 KHz and tune in signal noting dB level on an AC voltmeter connected 
> across speaker. Turn on calibrator, AC level should drop 2 to 3 dB.
>
> 6) Check UM9401 pin diodes on the high pass filter assembly, rear.
>
>
>
>                                                 RECEIVE      TRANSMIT
>
> ANODE CR1501                      MAX 0.9 V     11V TYP
>
> JUNCTION CR1502, CR1503          11 V TYP       MAX 0.9 V
>
> ther is a website that is still active
>
> http://www.zerobeat.net/drakelist/tr7bookalign.html
>
> that has more stuff
>
> 73 de Hank K7HP
>
>
>
> -
> ----- Original Message ----- 
> From: "GGLL" <nagato at arnet.com.ar>
> To: "Drake" <drake at mailman.qth.net>
> Sent: Wednesday, December 03, 2008 7:12 PM
> Subject: [Drake] TR-7 - Part two
>
>
>> Well, I've further checked the final amplifier; its components read 
>> within
>> tolerance; with the exception of idle currents, 400 mA for drivers, 130 
>> mA
>> for finals. I've reset them to 200 mA and 600 mA respectively.
>>
>> Anyway, 10 mtr. band still is way down in my wattmeter scale relative to
>> the other bands, 40..50 watts at most, and this when predriver adj. is 
>> set
>> for full gain (but in this situation, 80 Mtr. self oscillate).
>>
>> Final transistors tested ok in "diode" test mode, but, they have small
>> inverse leakage  from both enitter and collector to base (500 Kohms) when
>> tested with analog multimeter (R * 1K). Bases are left open, unsoldered.
>>
>> Any opinion, tip, etc. is surely welcome.
>>
>> Thanks in advance
>>
>> Regards
>> Guillermo - LU8EYW.
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>>
>>
>