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Author Topic: 75A1 is aligned but does not hear as well as Kenwood TS-820s  (Read 25814 times)
G3RZP
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Posts: 1225




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« Reply #30 on: September 15, 2014, 02:38:49 AM »

'5UP,

'I got me an........' is rather archaic: about 17th or maybe early to mid 18th century usage in the south west of the country, where I live.
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AC2EU
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« Reply #31 on: September 15, 2014, 05:33:19 AM »

All old radios suffer old radio problems to some degree. Over time resisters can go off tolerance and caps become leaky, etc.
Once those problems are addressed, the IFs should be peaked.
It's also possible that there is an AGC problem in that receiver.
The only way to know for sure when it's a subtle difference, is to test it with calibrated equipment while monitoring the circuit responses.

Even though those radios are very old, the superheterodyne was greatly refined by then. If everything is up to snuff, it should rival the sensitivity of modern receivers. Selectivity is another matter, though...

If you have the noise limiter on, that may impair the sensitivity too. They were rather "brute force" back then.
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K1YTG
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« Reply #32 on: September 22, 2014, 05:26:13 PM »

After many hours spent on the 75A-1 I happened upon a 75A-2 at a low flea market price of $100.  It was in much better shape than the first one.
That is running well and so now I have a good start on a collection with the 1, 2, and 75A-4.

The last flea market find is a SX100 that is coming along well.  It seems more sensitive then the Collins series.

The big feature of the Collins radios is knowing what frequency you are on.  As far as hearing well, there are lab tests to be seen on the internet showing the MDS for many of these old receivers.  Some of the best are RME   NAtional,  Drake.  Many are not the most expensive sets of their era.

As far as selling the radios, it is difficult to part with them as I spent so much time on them.  Its like selling my time for $5 per hour.

Norm

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