Hey ya Folks,
I am working on an Emerson FP-422, This is my 3rd radio, so i am very new at this and need a little guideance. I recaped the radio, and repalced the broken and shorted tuning capacitor and tested the tubes. So now when i turn on the set, it has static instead of a hum and the tone changes as i move through the scale. I tweek'd the IF slugs just a little and now receive a single station from about 850 all the way up. it seems to be strongest at about 1300. i am guessing that it is just an alignment issue, but at the moment i do not have any way to hook up my signal gen to inject any signals. below 850 i am able to hear the static change. any help would be great,
thanks
Dan Russell

Hi Dan

You mentioned something that makes me think it might be silver mica caps built into IF transformers. You adjusted IF slugs. Later IF transformers with slugs often cause static from built in caps.

Built in caps can be cut out and replaced by 100-120 pf.

Short out your antenna to see if static is still there? If it's still there it's internal to the radio. External static can be caused by lights, computer, motors etc.

Norm

:Hey ya Folks,
:I am working on an Emerson FP-422, This is my 3rd radio, so i am very new at this and need a little guideance. I recaped the radio, and repalced the broken and shorted tuning capacitor and tested the tubes. So now when i turn on the set, it has static instead of a hum and the tone changes as i move through the scale. I tweek'd the IF slugs just a little and now receive a single station from about 850 all the way up. it seems to be strongest at about 1300. i am guessing that it is just an alignment issue, but at the moment i do not have any way to hook up my signal gen to inject any signals. below 850 i am able to hear the static change. any help would be great,
:thanks
:Dan Russell

:Hi Norm,
I shorted the antenna to its self at the antenna connection lugs, the static is still there, and make some stronger crackles while shorted. i found some cables for my hp signal generator and injected 455kc into the grid of the 12sa7 through the stator lug of the antenna section as described in the riders manual, and i peaked the tone. it is good and strong. i continued to adjust the RF section as described in the riders vol 13 pg 17 and was unable to get a tone at 1400 or 600. interesting enough i could get 455kc to sound everywhere on the dial by just radiating from my sig gen cable. does this indicate an oscilator issue?

thanks, dan
Hi Dan
:
: You mentioned something that makes me think it might be silver mica caps built into IF transformers. You adjusted IF slugs. Later IF transformers with slugs often cause static from built in caps.
:
: Built in caps can be cut out and replaced by 100-120 pf.
:
: Short out your antenna to see if static is still there? If it's still there it's internal to the radio. External static can be caused by lights, computer, motors etc.
:
:Norm
:
::Hey ya Folks,
::I am working on an Emerson FP-422, This is my 3rd radio, so i am very new at this and need a little guideance. I recaped the radio, and repalced the broken and shorted tuning capacitor and tested the tubes. So now when i turn on the set, it has static instead of a hum and the tone changes as i move through the scale. I tweek'd the IF slugs just a little and now receive a single station from about 850 all the way up. it seems to be strongest at about 1300. i am guessing that it is just an alignment issue, but at the moment i do not have any way to hook up my signal gen to inject any signals. below 850 i am able to hear the static change. any help would be great,
::thanks
::Dan Russell

Hi Dan

By shorting the antenna it shows noise in in your radio and not outside interference.

Most likely silver mica leakage inside IF Transformers. Sometimes this will show up by measuring secondary voltage to ground on an IF Transformer. Voltage should be zero but may bounce up if there is a problem?

Voltage should be several volts negative on grid #1 (pin #5) of your 12SA7 if the oscillator is operating.

Norm

::Hi Norm,
:I shorted the antenna to its self at the antenna connection lugs, the static is still there, and make some stronger crackles while shorted. i found some cables for my hp signal generator and injected 455kc into the grid of the 12sa7 through the stator lug of the antenna section as described in the riders manual, and i peaked the tone. it is good and strong. i continued to adjust the RF section as described in the riders vol 13 pg 17 and was unable to get a tone at 1400 or 600. interesting enough i could get 455kc to sound everywhere on the dial by just radiating from my sig gen cable. does this indicate an oscilator issue?
:
:thanks, dan
:Hi Dan
::
:: You mentioned something that makes me think it might be silver mica caps built into IF transformers. You adjusted IF slugs. Later IF transformers with slugs often cause static from built in caps.
::
:: Built in caps can be cut out and replaced by 100-120 pf.
::
:: Short out your antenna to see if static is still there? If it's still there it's internal to the radio. External static can be caused by lights, computer, motors etc.
::
::Norm
::
:::Hey ya Folks,
:::I am working on an Emerson FP-422, This is my 3rd radio, so i am very new at this and need a little guideance. I recaped the radio, and repalced the broken and shorted tuning capacitor and tested the tubes. So now when i turn on the set, it has static instead of a hum and the tone changes as i move through the scale. I tweek'd the IF slugs just a little and now receive a single station from about 850 all the way up. it seems to be strongest at about 1300. i am guessing that it is just an alignment issue, but at the moment i do not have any way to hook up my signal gen to inject any signals. below 850 i am able to hear the static change. any help would be great,
:::thanks
:::Dan Russell

:Hi Norm
Today i shorted the antenna to the chassis using a jumper wire, and there was no sound, just a faint hiss. i did some more troubleshooting because i was a little afraid to take apart the IF cans. so i pulled out my sig gen, and input 1600 into the radio and got a tone, at 1600 or so. but i could not get one anywhere else. no matter where i moved the oscilator trimmer on the condensor, there was no change.so i went to the oscilator coil and measures between lug 1 and 2. it was open. i cheked my parts radios and it measured about 7 ohms in the circuit... i looked real close at the coil and found a tiny wire half the diameter of a hair hanging off. i changed the coil, and wham, it works great. i was able to tune the antenna and osc trimmers for max deflection and sound. thanks alot for your help. i hope this may help someone along the way. P.S. this is a thankyou present for my soon to be mother in law, my wedding is friday the 11th... haha wish me luck. thanks again
dan Sorry about the bad grammar and spelling, im excited
Hi Dan
:
: By shorting the antenna it shows noise in in your radio and not outside interference.
:
: Most likely silver mica leakage inside IF Transformers. Sometimes this will show up by measuring secondary voltage to ground on an IF Transformer. Voltage should be zero but may bounce up if there is a problem?
:
: Voltage should be several volts negative on grid #1 (pin #5) of your 12SA7 if the oscillator is operating.
:
:Norm
:
:::Hi Norm,
::I shorted the antenna to its self at the antenna connection lugs, the static is still there, and make some stronger crackles while shorted. i found some cables for my hp signal generator and injected 455kc into the grid of the 12sa7 through the stator lug of the antenna section as described in the riders manual, and i peaked the tone. it is good and strong. i continued to adjust the RF section as described in the riders vol 13 pg 17 and was unable to get a tone at 1400 or 600. interesting enough i could get 455kc to sound everywhere on the dial by just radiating from my sig gen cable. does this indicate an oscilator issue?
::
::thanks, dan
::Hi Dan
:::
::: You mentioned something that makes me think it might be silver mica caps built into IF transformers. You adjusted IF slugs. Later IF transformers with slugs often cause static from built in caps.
:::
::: Built in caps can be cut out and replaced by 100-120 pf.
:::
::: Short out your antenna to see if static is still there? If it's still there it's internal to the radio. External static can be caused by lights, computer, motors etc.
:::
:::Norm
:::
::::Hey ya Folks,
::::I am working on an Emerson FP-422, This is my 3rd radio, so i am very new at this and need a little guideance. I recaped the radio, and repalced the broken and shorted tuning capacitor and tested the tubes. So now when i turn on the set, it has static instead of a hum and the tone changes as i move through the scale. I tweek'd the IF slugs just a little and now receive a single station from about 850 all the way up. it seems to be strongest at about 1300. i am guessing that it is just an alignment issue, but at the moment i do not have any way to hook up my signal gen to inject any signals. below 850 i am able to hear the static change. any help would be great,
::::thanks
::::Dan Russell