In a few days, I will continue to work on the 17 with the IF and RF alignment but I am puzzled by the procedure at one point. While the service manual is very explicit on the procedure, there is one thing very vague - adjusting for maximum output. Maximum output on what, the 'S' meter, the 'Audio' output? The manual does state 'A rectifier type output meter is suggested as an output indicator' which seems to negate using the 'S' meter.
With that statement I suspect, it is saying to adjust for maximum 'Audio output' although, the manual does not state where to connect this meter but I would suspect the audio output terminals on the rear apron of the receiver. I intend to use my Simpson 260 connected to the audio output terminals as an indicator of 'Maximum'.
On 10/5/2019 10:29 AM, Bill (GroupOwner) wrote: In a few days, I will continue to work on the 17 withthe IF and RF alignment but I am puzzled by the procedure atone point. While the service manual is very explicit in theprocedure, there is one thing missing - adjusting for maximumoutput Maximum output on what, the 'S' meter, the 'Audio'output? Them manual does state 'A rectifier type output meteris suggested as an output indicator'. With that statement I suspect, it is saying to adjustfor maximum 'Audio' output' although, the manual does notstate where to connect this meter but I would suspect theaudio output terminals on the rear apron of the receiver. In a few days, I will continue to work on the 17 with the IF and RF alignment but I am puzzled by the procedure at one point. While the service manual is very explicit in the procedure, there is one thing missing - adjusting for maximum output Maximum output on what, the 'S' meter, the 'Audio' output?
Them manual does state 'A rectifier type output meter is suggested as an output indicator'. With that statement I suspect, it is saying to adjust for maximum 'Audio' output' although, the manual does not state where to connect this meter but I would suspect the audio output terminals on the rear apron of the receiver.
Using the AVC line will not give an accurate reading as it is always trying to compensate for the varying signal. Shut off the AVC and use the audio output for the indicator, no speaker required if it bothers you that much. I found the audio gain control works for me. I use a good old Simpson 260 for this using the OUTPUT position for an accurate dB scale as a reference as the signal generator output is varied. Use only enough signal to get a good indication and not overload the various stages. A scope or VTVM also works for an indicator but the 260, or similar) is what the manual is looking for and what Ive been using for over 50 years. When in doubt read the manual Carl.
Original Message - From: Dexter To: HallicraftersRadios@groups.io Sent: Saturday, October 05, 2019 10:56 AM Subject: Re: HallicraftersRadios Hallicrafters SX-17 IF and RF Adjustments Peak Indications? Bill, For many years I preferred to use a high impedance VTVM on the AGC line. This will give you a good steady negative dc reading to peak on. You can adjust the range of the meter if the signal strength goes off scale. I generally found it hard to get an ac reading off of the audio output.
By the time I got a good indication, the speaker was loud and annoying for a prolonged alignment session. With my late model DMM, its not too bad. On 10/5/2019 10:29 AM, Bill (Group Owner) wrote: In a few days, I will continue to work on the 17 with the IF and RF alignment but I am puzzled by the procedure at one point. While the service manual is very explicit in the procedure, there is one thing missing - adjusting for maximum output Maximum output on what, the 'S' meter, the 'Audio' output?
Them manual does state 'A rectifier type output meter is suggested as an output indicator'. With that statement I suspect, it is saying to adjust for maximum 'Audio' output' although, the manual does not state where to connect this meter but I would suspect the audio output terminals on the rear apron of the receiver. K2WH QRZ Biography - This email has been checked for viruses by AVG. On 10/5/2019 11:40 AM, Carl wrote:Using the AVC line will not give an accurate reading as it isalways tryingto compensate for the varying signal.If you're using an RF generator modulated at say 400 Hz instead ofan incoming signal, the AVC will be quite steady.
Otherwise you'vegot another problem. BTW AVC on or off should not matter, otherthan having to watch out for overload if it is set to manual.Shut off the AVC and use the audio output for the indicator, nospeakerrequired if it bothers you that much.
I found the audio gaincontrol worksfor me.How does one do this with the audio gain upstream from an outputmeter connected across the speaker voice coil. Bob C.- Original Message - From: DexterTo:Sent: Saturday, October 05, 2019 10:56 AMSubject: Re: HallicraftersRadios Hallicrafters SX-17 IF and RFAdjustmentsPeak Indications?Bill,For many years I preferred to use a high impedance VTVM on the AGCline.This will give you a good steady negative dc reading to peak on.You canadjust the range of the meter if the signal strength goes offscale.I generally found it hard to get an ac reading off of the audiooutput. Bythe time I got a good indication, the speaker was loud andannoying for aprolonged alignment session. On 10/5/2019 11:40 AM, Carl wrote: Using the AVC line will not give an accurate reading as it isalways trying to compensate for the varying signal.
Ifyou're using an RF generator modulated at say 400 Hz instead of an incomingsignal, the AVC will be quite steady. Otherwise you've got anotherproblem. BTW AVC on or off should not matter, other than having to watchout for overload if it is set to manual. Shut off the AVC and use the audio output for the indicator,no speaker required if it bothers you that much. I found the audio gaincontrol works for me.
How does one do this with theaudio gain upstream from an output meter connected across the speaker voicecoil. Original Message - From:Dexter To: Sent:Saturday, October 05, 2019 10:56 AM Subject: Re: HallicraftersRadiosHallicrafters SX-17 IF and RF Adjustments Peak Indications? Bill, For many years I preferred to use a high impedanceVTVM on the AGC line. This will give you a good steady negative dcreading to peak on. You can adjust the range of the meter if the signalstrength goes off scale. I generally found it hard to get an ac readingoff of the audio output. By the time I got a good indication, thespeaker was loud and annoying for a prolonged alignment session.
With mylate model DMM, its not too bad. On 10/5/201910:29 AM, Bill (Group Owner) wrote: In a few days, I will continue towork on the 17 with the IF and RF alignment but I am puzzled by theprocedure at one point. While the service manual is very explicit inthe procedure, there is one thing missing - adjusting for maximumoutput Maximum output on what, the 'S' meter, the 'Audio' output? Them manual does state 'A rectifier type output meter is suggestedas an output indicator'. With that statement I suspect, it issaying to adjust for maximum 'Audio' output' although, the manual doesnot state where to connect this meter but I would suspect the audiooutput terminals on the rear apron of thereceiver. K2WH QRZBiography - This email has been checked for virusesby AVG. Standard procedure on virtually all vacuum tube radios was to monitor the audio output.
Hallicrafters Sx-17
Hang an AC meter, a VOM will do nicely, across the speaker voice coil, or in sets taking an external speaker, across a load resistor on the speaker output. RF and IF alignment is usually done with the AVC off. Use the minimum output from the generator that will overcome the noise. Reduce the output of the generator as necessary as the signal is peaked. In most cases use an AM signal, about 400Hz at about 30% modulation, its not critical.
With a VTVM one can also monitor the DC level across the diode load resistor. The signal need not be modulated for that. This will be proportional to the RF at the detector.
The main idea of keeping the RF level low is to prevent overload. Also, when aligning sets where the AVC can not be disabled it prevents detuning from the bias shifting. This is also the reason for doing alignments with the RF gain near maximum. The amount of detuning is minimal on well-designed sets but the procedure is of some value with broadcast receivers etc. I thought I had an SX-17 instruction book but can't find it.
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Hallicrafters Sx 110
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