PW 208 Bandspread Portable restoration - alignment - UK Vintage Radio Repair and Restoration Discussion Forum

davidh2019 · 5th Jul 2020, 7:39 pm

Hi
Further info from a previous post inc circuit diags.
See https://www.vintage-radio.net/forum/...d.php?t=168193

I have changed the electrolytic caps as suggested in the previous post but with no improvement in performance of the radio. I even temporarily replaced the RF stages decoupling caps with no improvement either.

However re alignment has been much more successful and the set is working reasonably on MW.

I have never aligned a radio before and I started by aligning the IFTs to 470KHz using a Digimess SG100 sig gen.

IFT 1 and 2 peaked with just a little tweek of the slug however IFT 3 is no where near as sensitive and I can twiddle the core quite a lot both up and down with no sensitive spot like I obtained with IFT1 and 2.

On IFT3 should I get the same sensitivity as IFT1 and 2?

Nuvistor · 5th Jul 2020, 8:20 pm

If IFT3 feeds the detector it will not be as “peaky” But would expect some rise when on tune.

crackle · 5th Jul 2020, 8:50 pm

Have you tried turning the signal generator output right down so you can hardly hear it.

Mike

5th Jul 2020, 7:39 pm	#1
davidh2019 Diode Join Date: Apr 2020 Location: Wokingham, Berkshire, UK. Posts: 7	PW 208 Bandspread Portable restoration - alignment Hi Further info from a previous post inc circuit diags. See https://www.vintage-radio.net/forum/...d.php?t=168193 I have changed the electrolytic caps as suggested in the previous post but with no improvement in performance of the radio. I even temporarily replaced the RF stages decoupling caps with no improvement either. However re alignment has been much more successful and the set is working reasonably on MW. I have never aligned a radio before and I started by aligning the IFTs to 470KHz using a Digimess SG100 sig gen. IFT 1 and 2 peaked with just a little tweek of the slug however IFT 3 is no where near as sensitive and I can twiddle the core quite a lot both up and down with no sensitive spot like I obtained with IFT1 and 2. On IFT3 should I get the same sensitivity as IFT1 and 2?

5th Jul 2020, 8:20 pm	#2
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: PW 208 Bandspread Portable restoration - alignment If IFT3 feeds the detector it will not be as “peaky” But would expect some rise when on tune. __________________ Frank

5th Jul 2020, 8:50 pm	#3
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: PW 208 Bandspread Portable restoration - alignment Have you tried turning the signal generator output right down so you can hardly hear it. Mike