Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

FM Alignment of 48-482
#1

I am trying to finish up the alignment of one of these and am having trouble with getting the oscillator set to the proper frequencies at both ends of the dial. The instructions have you align at 88Mc and 105Mc. You adjust the oscillator coil at 88Mc and the trimmer cap at 105Mc. I find that I have to keep compressing the windings of the coil at 88Mc and keep withdrawing the trimmer cap at 105Mc. On each iteration I get closer but I have reached the extent of how close together I can get the windings of the coil. It seems that the oscillator should be running on the low side of the received signal (i.e. received frequency-I.F.). With this case I would need the oscillator to run at 78.9Mc for 88Mc and 95.9Mc for 105Mc. I have been checking the frequency of the oscillator with a coil of wire wrapped around the 7F8 tube and connected to my frequency counter. With the coil compressed I can get 78.9Mc with the dial set at 88Mc but when I set the dial to 105 I get about 93Mc from the oscillator. I spread the coil windings out as much as they would go and withdrew the trimmer cap as far as it would go to see if I could get the oscillator to run on the high side (received frequency+I.F.). At 105Mc it will oscillate at about 118Mc but at 88Mc it will only oscillate at about 88Mc so it does not seem that high side oscillating will work. Has anybody else had any problems with getting the FM dial to align on one of these sets? I know it isn't going to be completely accurate but I would think I could get it closer than 3Mc.

Sean
WØKPX


Messages In This Thread
FM Alignment of 48-482 - by Sean - 11-21-2009, 11:06 AM
Re: FM Alignment of 48-482 - by Ron Ramirez - 12-01-2009, 08:29 AM
Re: FM Alignment of 48-482 - by Terry Judkins - 12-03-2009, 10:53 PM
Re: FM Alignment of 48-482 - by Sean - 12-05-2009, 05:21 PM
Re: FM Alignment of 48-482 - by DCASAZZA - 12-10-2009, 09:38 AM
Re: FM Alignment of 48-482 - by Don Lind - 12-12-2009, 02:27 PM
Re: FM Alignment of 48-482 - by Sean - 01-05-2010, 09:50 AM
Re: FM Alignment of 48-482 - by Ron Ramirez - 01-05-2010, 11:08 AM
Re: FM Alignment of 48-482 - by Sean - 01-09-2010, 02:08 PM
Re: FM Alignment of 48-482 - by Ron Ramirez - 01-09-2010, 03:06 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
That looks a lot like an aircraft connector of some kind, even if it's a U.S.N power supply. I have a book somewhere abo...Arran — 02:56 AM
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
hello david, I have a similar generator in my collection that features a cast iron, single-cylinder Briggs & Stratt...radiorich — 01:00 AM
under chassis parts locator diagram for 1938 Zenith 9s262
Has anyone gone to the trouble of creating an under chassis parts locator image?  Yes, I can identify components by foll...bobloney — 08:57 PM
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
Try looking at this site the book mark is for a old generator that I was given. David    https://radionerds.com/index.ph...David — 08:36 PM
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
Hello Everyone, I am looking for voltage identification for all the pin positions on the socket of a CRV-20130 power su...Tonym4704 — 08:16 PM
Philco P45-6365 Universal Transformer Instruction Manual
Can anyone guide me to where this may be found?GRG — 03:00 PM
54C Complete Teardown/Rebuild
I don't think that I have encountered a 12Z3 before, curious how it uses one of those but includes a #43, which is a 25 ...Arran — 02:17 PM
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM

[-]
Who's Online
There are currently no members online.

>