[TenTec] Some Argo 515 questions

[WA3FIY]

On 9 Mar 2003 at 7:57, genewill at ordata.com wrote:

> I'm discovering the joys of a vintage Argonaut 515. I have some questions
> the manual doesn't answer, and I haven't found in the reflector archives:
> 
Nice little rig!

> 1. On 40m CW I hear both sides of zero beat, about equally; on 20m CW the
> unwanted side is audible, but quite far down in strength. Is this normal?
> 
Yours likely needs alignment.   As I write this I am listening to some CW on 40, and 
the signal is present only on one side of zero beat.  Likewise on 20, but you will 
notice that as you tune UP in frequency on 80 and 40 the pitch of the signal goes UP.  
As you tune UP in frequency on 20 - 10, the pitch goes DOWN.   That is because the 
radio automatically switches sidebands for convenience on SSB and uses the same 
BFO oscillator on CW as on SSB.   So........since yours works OK on 20 meters but 
not 40 and since the 515 switches BFO crystals on 40, I would guess that the LSB 
BFO crystal needs alignment.   The owners manual has the procedure for doing that.

> 2. A "T" voltage is brought out to the accessory connector on the rear
> panel. Can this be used with a relay to drive an amp correctly -- i.e.,
> with enough lead time before RF appears to avoid hot-switching? Can
> someone point me to a circuit?
>
There is a few milliseconds lead time in the "T" voltage.   I guess the question is, how 
much lead time do you need?    In event you use the "T" voltage, be sure to buffer it 
through a switching transistor or FET to protect the 515 and to provide enough drive 
for your external switching circuit.   Do not add an external relay though.   That will 
just add delay time in T/R switch over.   I can provide additional info if you are 
interested.
 
> 3. As I read the schematic, the 208A audio filter connects through the
> accessory port into/before the AGC loop, for superior filtering. Can a
> filter such as the Autek QF-1A be connected there and also function
> correctly?
> 
Probably most audio filters will work OK if the gain is approximately unity and if the 
delay through the filter is small.   The delay matter is important because the filter is 
inside the AGC loop and excessive delays in the filter will destroy the AGC action.  
DSP type filters will likely add too much delay to be useful.

-- 

73 de Lee  WA3FIY
wa3fiy at radioadv.com

"We estimate the wisdom of nations by seeing what they did with their surplus 
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