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Old 13th Sep 2020, 3:19 pm   #41
Tyso_Bl
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Default Re: FRG-7. Very quiet

Quote:
Originally Posted by Phantomrose1999 View Post
I measured the BC antenn socket to ground. 0.6 ohms. When the ATT is in the middle position.

87.9 ohms when in the DX position

9.6 ohms when in the local position.

Almost a short between ground and the alBC antenna signal terminal. Donít think this is normal and may explain what is happening.
You are measuring the DC resistance of the the primary of the T101/2/3/4 front end transformers, look at the circuit diagram...

T
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Old 13th Sep 2020, 3:41 pm   #42
Phantomrose1999
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Default Re: FRG-7. Very quiet

Quote:
Originally Posted by Tyso_Bl View Post
Quote:
Originally Posted by Phantomrose1999 View Post
I measured the BC antenn socket to ground. 0.6 ohms. When the ATT is in the middle position.

87.9 ohms when in the DX position

9.6 ohms when in the local position.

Almost a short between ground and the alBC antenna signal terminal. Don’t think this is normal and may explain what is happening.
You are measuring the DC resistance of the the primary of the T101/2/3/4 front end transformers, look at the circuit diagram...

T
Quite right. Checked all the coils they are the same. Also did another test with a wire connected to the radio and the signal gen lead wrapped around the antenna wire. Could get a signal at 1mhz but had to crank up the high setting of the generator. This I think the radio seems to be working just incredible insensitive.

What should I see at TP107 ?
Does the first mixer IC fail ? I found no measurable output at pin 3 with my digital Cro.
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Old 14th Sep 2020, 4:24 pm   #43
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Default Re: FRG-7. Very quiet

Quick update.

I am chasing the 52mhz signal that is mixed at Q105.

I am getting a signal at Q109. Can see a signal that peaks every 1mhz while tuning the main vfo. Can’t see anything beyond Q109, the led drivers are not getting signal to turn around t on/off

Will remove Q109 and test it. Seems to get a signal at the base that peaks every 1mhz but nothing at the collector.
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Old 14th Sep 2020, 4:32 pm   #44
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Default Re: FRG-7. Very quiet

You are getting close...
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Old 16th Sep 2020, 11:50 am   #45
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Default Re: FRG-7. Very quiet

Great news ! Fixed.

https://youtu.be/s_CukzwFccI

As mentioned there was almost no output at TP104. Even after replacing the Q101 and Q104. It was able to pick up strong signals including some BC stations. That is what threw me. Next I checked all oscillators and they were working So I checked the signal from pin 3 of Q106 through Q107, Q108, Q109. Then I found no signal beyond Q109 !

Removed Q109 and found it to be dead. Removed Q108 and it had an hfe of 90.

I had two 2SC930’s which had a hfe of 110 and 130. So I put them in as they are pin compatible and was so excited that it was picking up shortwave with just a wire. So all good.

Will recap the unit someday.
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Old 16th Sep 2020, 12:04 pm   #46
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Default Re: FRG-7. Very quiet

Had to delete the video because something is confusing.

Why am I getting a 53 MHz signal at TP104 ? The schematic says it should be 2-3mhz.
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Old 16th Sep 2020, 12:11 pm   #47
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Default Re: FRG-7. Very quiet

This is my output at TP104. Anyone care to explain what I am seeing ? It’s the same signal regardless if a station is tunned or not. Nothing anywhere near the 2-3mhz the schematic indicates.
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Old 16th Sep 2020, 12:26 pm   #48
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Default Re: FRG-7. Very quiet

TP104 is connected to the drain of the mixer, Q105 via a 22pF capacitor. Q105 is a simple mixer, the output of which will be composed of the signals made up from the input into the gate, the input into the source, the sum of these, the difference frequency plus the many harmonics and their sums and products.

The source load of Q105 only a choke, not a tuned circuit, so you will see the whole lot of frequencies when you look at TP104, although some may be attenuated a little by the tuned circuit formed by T401, VC2 and TC401 which is fairly loosely coupled to the output of the mixer. The difference frequency of 2-3MHz is selected by the tuned circuits later on (T401, VC2 and TC401 then T402, VC2 and TC402)

I expect the dominant signal to be the one from the oscillator side chain, which presumably is 53MHz. The good news for you is that all is as it should be.

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Old 16th Sep 2020, 12:44 pm   #49
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Default Re: FRG-7. Very quiet

Thanks Paula. Makes sense.

I have reposted the video.

https://youtu.be/rzqkE3nVob8

Working very well. Am really pleased with it. Will hook it up to my 6m copper loop and try for 40m hams tomorrow.
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Old 16th Sep 2020, 8:01 pm   #50
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Default Re: FRG-7. Very quiet

A good conclusion. Enjoy it now.
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Old 17th Sep 2020, 11:22 am   #51
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Default Re: FRG-7. Very quiet

40M with my indoor 6m loop with brick walls all around. When this loop is outside it’s 10x better. But pretty happy to hear a 40m

https://youtu.be/WmZh5ZmK8-4

Listening to 80m while typing.
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Old 17th Sep 2020, 1:56 pm   #52
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Default Re: FRG-7. Very quiet

Surprised to hear a "VK" but then noted your location

Nice result!
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Old 18th Sep 2020, 8:57 am   #53
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Default Re: FRG-7. Very quiet

Setup my primitive loop outside and compared the frg-7 to a Marc double conversion.

Was listening to a US ham on 40m, then switched antenna to the Marc and wow ! What a difference. So loud and clear on the Marc. With the RF sensitive cranked down to half.

But not a pretty as the frog

https://youtu.be/488qQqY4u2Q

Last edited by Phantomrose1999; 18th Sep 2020 at 9:10 am.
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