Racal RA17C tips - Page 4 - UK Vintage Radio Repair and Restoration Discussion Forum

Skywave · 30th Apr 2017, 7:34 pm

Several RA-17s have passed through my hands in which I replaced the BFO assembly with a product detector. The improvement was worth the effort.

Al.

dtvmcdonald · 30th Apr 2017, 7:40 pm

Exactly what was the improvement? I've tried a product detector on
a couple of receivers and noticed no significant improvement. These all
had, however, plenty of BFO injection, and I never ever tried them
with really high S/N ratio SSB signals, best S/N was probably 30 dB at best.

Keith · 2nd May 2017, 4:00 pm

I regularly use an RA17C-12 and find it's SSB performance to be perfectly adequate without any modification.

Skywave · 3rd May 2017, 12:14 am

Quote:

Originally Posted by Skywave

Several RA-17s have passed through my hands in which I replaced the BFO assembly with a product detector. The improvement was worth the effort.

Quote:

Originally Posted by dtvmcdonald

Exactly what was the improvement?

Improved resolution of strong SSB signals. The need to reduce the IF gain and increase the AF gain is much less required, if at all. However, there a several suggested ccts. around for a PD for a RA-17: not all will show much of an improvement. Moreover, please note that I am talking about the RA-17 and the RA-17L. I have no experience of the RA17C-12.

Al.

Radio Wrangler · 3rd May 2017, 6:17 am

The RA117 may be worth looking at. It has as standard an S meter reading the AGC line which manages to work normally on CW and SSB, so the AGC is definitely active. The 3-way knob switch for the meter is the obvious difference on the front panel in place of the RA17's toggle switch. You also get a full Watt of audio.

In the early 1980s I bought an RA117 from John's Radio in Birkenshaw (Nr Bradford) The receiver was NOS, taken right out of long-term packaging and put into a slim metal cabinet from a batch which John had had made locally. Inside, the castings gleamed! I used it on aM CW and SSB without an SSB adaptor. I wondered about one, but never happened to find one.

David

Keith · 3rd May 2017, 9:43 am

The RA17C-12 seems to many many similarities with the RA117 - it too has the 3 position meter switch which includes an S-meter position. Possibly it has the same AGC arrangements. I've certainly never had to reduce the RF gain to resolve SSB signals.

Radio Wrangler · 3rd May 2017, 11:36 am

Ah, that may explain things. Thanks, Keith

David

30th Apr 2017, 7:34 pm	#61
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Racal RA17C tips Several RA-17s have passed through my hands in which I replaced the BFO assembly with a product detector. The improvement was worth the effort. Al.

30th Apr 2017, 7:40 pm	#62
dtvmcdonald Pentode Join Date: Mar 2016 Location: Champaign, Illinois, USA. Posts: 227	Re: Racal RA17C tips Exactly what was the improvement? I've tried a product detector on a couple of receivers and noticed no significant improvement. These all had, however, plenty of BFO injection, and I never ever tried them with really high S/N ratio SSB signals, best S/N was probably 30 dB at best.

2nd May 2017, 4:00 pm	#63
Keith Heptode Join Date: Jan 2003 Location: Tewkesbury, Gloucestershire, UK. Posts: 693	Re: Racal RA17C tips I regularly use an RA17C-12 and find it's SSB performance to be perfectly adequate without any modification. __________________ Keith Yates - G3XGW VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm

3rd May 2017, 6:17 am	#65
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,858	Re: Racal RA17C tips The RA117 may be worth looking at. It has as standard an S meter reading the AGC line which manages to work normally on CW and SSB, so the AGC is definitely active. The 3-way knob switch for the meter is the obvious difference on the front panel in place of the RA17's toggle switch. You also get a full Watt of audio. In the early 1980s I bought an RA117 from John's Radio in Birkenshaw (Nr Bradford) The receiver was NOS, taken right out of long-term packaging and put into a slim metal cabinet from a batch which John had had made locally. Inside, the castings gleamed! I used it on aM CW and SSB without an SSB adaptor. I wondered about one, but never happened to find one. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

3rd May 2017, 9:43 am	#66
Keith Heptode Join Date: Jan 2003 Location: Tewkesbury, Gloucestershire, UK. Posts: 693	Re: Racal RA17C tips The RA17C-12 seems to many many similarities with the RA117 - it too has the 3 position meter switch which includes an S-meter position. Possibly it has the same AGC arrangements. I've certainly never had to reduce the RF gain to resolve SSB signals. __________________ Keith Yates - G3XGW VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm Last edited by Keith; 3rd May 2017 at 9:43 am. Reason: Typo

3rd May 2017, 11:36 am	#67
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,858	Re: Racal RA17C tips Ah, that may explain things. Thanks, Keith David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done