[MRCA] [Milsurplus] ATA ARA RX Alignment Question

[Ray Fantini]

What I do in an AM or CW receiver alignment is establish a signal level with no signal on the output, them with the receiver set to MGC inject a signal that will give you ten to twenty dB over noise level and occasionally use the receivers gain control if it becomes to high a display on the meter. Generali start with around one to ten Mv at the output of the mixer stage decoupled thru a 0.01 capacitor.  Think when done you can see ten dB over noise at detector sometimes down to 10 to 30 microvolts and an overall performance of ten dB over noise with 3 to 10 microvolts from the antenna input. Not high performance by the standards of receivers today but not bad for a old signal conversion design. Below forty meters sensitivity below 10 microvolts is about useless considering the ambient noise  on the HF band, I am more into reduced or low level of internal noise as a factor of HF receiver performance and that's a good low level on the BC-348
Think the need to crank up the signal generator level may be more pronounced on a receiver that's more out of alignment. Also some people will strictly adhere to the procedure that you must put the radio in MVC and turn the gain all the way up and use the generator output to adjust your readings, I think it works somewhat the same way as long as the AVC/AGC systems are disabled.

On that receiver and a couple others found that the trimers for the RF stages are always stiff and like I said sometimes you can do more damage breaking them and never have seen them far off unless someone has cranked on them before.

The soldering thing is just have a habit of trying to keep the iron and gun as clean as possible, that and trying to keep the temperature down to just what's necessary to do the job. Always though that the scum that's left from the resin or what ever is what eats up the tip but don't know really. Know I have been going thru tips on the Weller gun a lot working on these old radios, espicaley when de-soldering.

Ray F/KA3EKH


From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> On Behalf Of Jim Whartenby via Milsurplus
Sent: Monday, August 18, 2025 12:51 PM
To: List Milsurplus <milsurplus at mailman.qth.net>; Military Radio Collectors Association (mrca at mailman.qth.net) <mrca at mailman.qth.net>
Subject: Re: [Milsurplus] ATA ARA RX Alignment Question


Ray,
I've had good luck putting moderate torque with a plastic tool and just holding it for a minute or two.  9 times out of 10 it will turn with a snap and then rotate feely.  Patients is key.

I noticed in the video that you didn't adjust the signal generator output down as you adjusted the IFTs.  I have found that you get a well defined IFT peak at low RF inputs where the AGC is not controlling gain.  At what output level was your signal generator set?

The other silly thing I noticed is that you clean the soldering tip before you store it in the holder.  I always leave a bit of solder on it to prevent oxidation of the tip.  I have never lost a soldering iron tip but I can't say the same for the Weller TCP heating element!
Jim

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