Re: Looking for analog receiver suggestions (not necessarily modern nor ultralight)


Todd
 

Hi Jay,

The Sangean PR-D3 does produce a degree of soft muting (probably equal to the Crane CC 2E). This is most noticeable when the PR-D3 is used 'barefoot'. Most non-DXer listeners use their radios without any additional antenna. Mainly fringe area listeners would receive somewhat compromised reception of weak AM signals. However, the situation with DXers is different. They know that serious DX reception is highly inefficient without at least a medium size loop, or FSL antenna used with a sensitive portable radio. 

When a medium size size loop antenna is tuned to resonance, and the radio is positioned next to the loop at the optimal distance, the soft mute feature is completely negated. The loop antenna high signal signal pickup effectively acts as the first RF stage. This is especially true with larger higher gain loop or FSL antennas. A faint signal reading 0 bar strength can dramatically increase to full bar strength when a loop is tuned to resonance. The most sensitive 'barefoot' portable radio in the world will be greatly outperformed by an average sensitivity radio inductively coupled to a high gain loop. This is why small differences in 'barefoot' RF AM sensitivity are not important for serious DXers. Selectivity, and overload-desensitization performance is more important.

I was able to compare the 'barefoot' RF sensitivity differences by tuning to a weak stable distant groundwave AM signal noon. The best time to do this testing is when there is a major power blackout where all house and street light power is temporarily off. Remote rural areas without power poles are also ideal. Not very practical, but ideally there should only be QRN (natural noise) when doing sensitivity comparison testing.

There is a drop in signal when even tuned only 1 KHz away from the center wanted AM channel. I assume this also applies to the Crane CC 2E. This is a disadvantage when attempting to 'slope tune' in order to obtain a better signal within the selectivity curve. The 1 KHz tuning offset signal drop is not as great on the Sangean PR-D15.

Again like the Crane CC 2E, the PR-D3 AM memory preset stations on AM will sometimes not optimally tune the twin-coil antenna system, hence the rotary 1 KHz step knob needs to be re-tuned back to get full signal. This slight inconvenience is worth tweaking to obtain the strongest signal.

The PR-D3 front display is exactly the same as the Crane CC 2E. The weather and two meter ham band markings are on the display, but of course do not light up.

The Crane CC 2E auto-alignment feature also works on the PR-D3.

Compared to the more bullet-proof superior RF MW design of the Sangean PR-D15, the PR-D3 and CC Crane 2E more easily desensitize when a loop is aimed towards a local MW transmitter site. This desensitization factor requires loop placement further away from the radio. Optimal inductive coupling varies with frequency. Higher frequencies such as 1575 KHz require closer loop placement. Optimal loop placement is obtained by trial and error for every unique mix of factors.

The Sangean PR-D15 (and possibly PR-D5) is exceptionally selective on AM. You may want to verify this for documenting on your website. A simple test is 10 KHz adjacent signal readability for a skywave signal next to a strong local.

Most portable radios should be operated by DC batteries for the lowest RF noise floor and associated higher sensitivity. AC power operation introduces a slight continuous buzz on the PR-D3. The PR-D15 buzz is much more dramatic.

I found the Panasonic DR-22 at the front of someone's house. It was thrown out with some other AM/SW portables. The DR-22 RF sensitivity is way down, hence needs alignment or switch contact clean maintenance. I don't know anyone near me that specializes in restoring old radios. I may someday attempt to align it using the service manual. But I don't see the point of using an old radio that doesn't offer accurate digital readout down to 1 KHz steps. 

Regards,

Todd

https://www.canohm.com.au/products/radios/sangean?view=article&id=593#downloads

https://www.canohm.com.au/images/product-ranges/Sangean/Sangean-AR-pdf/PR-D3G.pdf

https://www.canohm.com.au/images/product-ranges/Sangean/Sangean-AR-pdf/PR-D3_Manual.pdf

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