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 Post subject: Heathkit AR-2 Receiver
PostPosted: Sep Fri 14, 2018 4:26 pm 
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Joined: Sep Sat 26, 2015 8:30 pm
Posts: 73
Hello everyone,

I have a AR-2 with SMD. Would anyone know the suggested capacitor values for both the 1st and 2nd IF cans ?

Thank you,

Bill


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Fri 14, 2018 4:46 pm 
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Joined: Oct Sun 04, 2015 8:22 pm
Posts: 71
Location: Newton, MA 02465
You can download a manual, which includes a schematic and parts list, here.

Hope this helps.

- Bruce K1FFX


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Fri 14, 2018 5:03 pm 
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Joined: Sep Sat 26, 2015 8:30 pm
Posts: 73
Hi Bruce,

Thanks for the reply. I do have that manual but it only gives the part no. for the IF cans but does not indicate the actual values of the mica sheets inside the can which make up the capacitors for the primary and secondary sides of the coils.

Those mica sheets need to replaced with an actual capacitor such as a disc or mica type. My problem is, I don't know the correct values to use for each IF can. There would be two capacitors needed for each can.

Thanks Bruce.

Bill


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Fri 14, 2018 7:56 pm 
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Joined: Jun Sun 19, 2011 2:31 pm
Posts: 5739
Bill,

Use dipped mica and not disc capacitors for these replacements. Typical values I have run across are between 300-520 pf and most used the same value on both input and output sides but I am sure there are exceptions.

If you have a capacitance meter and one of the mica leaf type capacitors is still functional isolate and measure the capacitor. Alternatively you can use a signal generator and scope (or RF voltmeter) to measure the transformer and either try different mica values in the expected range OR use a variable capacitor to find what value is needed to resonate the winding. A grid dip meter with a 455 Khz. coil would work for measuring also but those aren't common.

I would tack in a couple of 510 pf capacitors and see if that allows the transformer to peak normally.

Rodger WQ9E


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Fri 14, 2018 9:11 pm 
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Joined: Sep Sat 26, 2015 8:30 pm
Posts: 73
Hi Roger,

Sounds good. That gives me a place to start. Thank you for the advise.

Bill


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Sat 15, 2018 12:45 am 
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Joined: Dec Sun 14, 2008 3:33 pm
Posts: 738
Location: Tokyo
Rodger, my Knight Star Roamer had silver mica migration disease in its 455KHz IFTs. I removed the built in caps, and replaced them with external caps. IIRC, the new caps were just 100~120pF. I'll have to look inside to check.

Rob


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Sat 15, 2018 12:54 am 
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Joined: Sep Sat 26, 2015 8:30 pm
Posts: 73
Thanks guy's, good info !!

Bill


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Sat 15, 2018 6:46 am 
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Joined: Dec Sun 14, 2008 3:33 pm
Posts: 738
Location: Tokyo
Checked the Star Roamer: I had replaced the original internal IFT caps with external 100pF mica, primaries and secondaries.


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 Post subject: Re: Heathkit AR-2 Receiver
PostPosted: Sep Sat 15, 2018 2:22 pm 
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Joined: Sep Sat 26, 2015 8:30 pm
Posts: 73
Thanks Rob - I'll try it.

Bill


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