[Boatanchors] Hammarlund Pro 310 Rcvr on eBay

[WQ9E at btsnetworks.net]

Richard,

The Pierson KP-81 was a post WWII design, only produced for a very short time.  I have a couple of them and they are interesting receivers.  The receiver uses a moving coil catacomb like the National NC-100 family.  The receiver is single conversion but uses a very large number of IF transformers which are split between two plug in chassis on either side of the receiver.  Mechanically it is very robust with great tuning feel and very heavy duty variable capacitors.  It has some cute features including lamp assemblies which project the tuning indicators on the dial, a built in calibrator that is activated by turning the band spread dial to the set position (which also grounds the antenna input), separate noise limiters for phone and CW, multiple setting high and low pass audio filters, and an effective squelch system.

But I am sure the company lost a lot of money since the production cost must have been very high.  Both the main and band spread capacitors have spring counterbalance systems to offset the weight of the very heavy gauge rotor plates and these are somewhat tedious to set up properly.  Any maintenance in the front end is very difficult.  

My receivers both came with preliminary manuals with a note that a full manual would be printed and mailed but I am sure the company went under before a full manual was ever created.  The followup KE-93 mobile receiver is interesting but is definitely not a "miniature KP-81" as claimed in the advertising.  It is a decent receiver but the performance is not commensurate with the complexity.

Rodger WQ9E

-------- Original Message --------
> From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
> Sent: Thursday, December 29, 2011 7:46 PM
> To: "David Knepper" <collinsradio at comcast.net>, <W9RAN at oneradio.net>, <boatanchors at mailman.qth.net>
> Subject: Re: [Boatanchors] Hammarlund Pro 310 Rcvr on eBay
> 
 Their concept was completely new, at least 
> to the field. Receivers like the Cardwell and Pierson (do I 
> have that name right) might have seemed super in the late 
> 1930's but too much was going on in the mid to late 1940s 
> and they just didn't make it; they were essentially just 
> glorified older designs.
>      I am not sure what happened to Hammarlund: while the 
> SP-600 was a good design most of the later stuff left a lot 
> to be desired. There is probably a book in this but someone 
> else will have to write it.
> 
> 
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com 
> 
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