Fisher Type RP-44 info needed

[Ralph Seefeld]

Recently I acquired what appears to be a radio direction finding
receiver manufactured by Fisher Research Lab in Palo Alto CA. It is
Type RP-44, serial no. 267. Tube lineup is: 6SK7 RF, 6K8 converter,
6SK7 IF, 6SK7 BFO, 6SQ7 1st AF-Det, 6K6 output. It has three bands, but
frequencies are unknown as there is only one tuning scale, marked from
0-100. With it I received what looks like a loop antenna which fits on
top at the center of a compass rose. It appears to be powered through a
multi-pin connector on the back.

When a friend found out that I was interested in old radios, he offered
this to me along with some other gear that had been stored in his shed
for years. The rest I disposed of as worthless, but even though I had
to clean a rats nest out of it, I thought this unit might be worth
saving and possibly restoring.

I could find no info on the web, but I did find the company, which is
still in business, mainly in the manufacture of metal detectors. An
e-mail to the company brought the response that they had no information
on this unit, not even in their archives.

I could always trace the wiring (which looks to be in good shape under
the chassis), but a schematic would be a big help, and any other
information would be great.

Ralph Seefeld

[Jim Mueller]

Love the speaker grill!

It looks like this has more problems than salt spray. What is the inside
like?

Have fun with it.

--
Jim Mueller

To get my real email address, replace wrongname with eportiz. Then replace
nospam with sacbeemail.

"Ralph Seefeld" > wrote in message
...
> Recently I acquired what appears to be a radio direction finding
> receiver manufactured by Fisher Research Lab in Palo Alto CA. It is
> Type RP-44, serial no. 267. Tube lineup is: 6SK7 RF, 6K8 converter,
> 6SK7 IF, 6SK7 BFO, 6SQ7 1st AF-Det, 6K6 output. It has three bands, but
> frequencies are unknown as there is only one tuning scale, marked from
> 0-100. With it I received what looks like a loop antenna which fits on
> top at the center of a compass rose. It appears to be powered through a
> multi-pin connector on the back.
>
> When a friend found out that I was interested in old radios, he offered
> this to me along with some other gear that had been stored in his shed
> for years. The rest I disposed of as worthless, but even though I had
> to clean a rats nest out of it, I thought this unit might be worth
> saving and possibly restoring.
>
> I could find no info on the web, but I did find the company, which is
> still in business, mainly in the manufacture of metal detectors. An
> e-mail to the company brought the response that they had no information
> on this unit, not even in their archives.
>
> I could always trace the wiring (which looks to be in good shape under
> the chassis), but a schematic would be a big help, and any other
> information would be great.
>
> Ralph Seefeld
>

[Ralph Seefeld]

Judging from the nice under-chassis condition, I would say salt spray
wasn't a problem. Rodents were the culprits. They were able to enter
the casing, but couldn't get below. Here's more pix. I'm sure the tube
sockets will need close attention, and who knows what I'll find inside
the IF and RF cans? That is, if I decide to attempt a restoration.

Jim Mueller wrote:
> Love the speaker grill!
>
> It looks like this has more problems than salt spray. What is the inside
> like?
>
> Have fun with it.
>

[jakdedert]

Ralph Seefeld wrote:
> Judging from the nice under-chassis condition, I would say salt spray
> wasn't a problem. Rodents were the culprits. They were able to enter
> the casing, but couldn't get below. Here's more pix. I'm sure the tube
> sockets will need close attention, and who knows what I'll find inside
> the IF and RF cans? That is, if I decide to attempt a restoration.

I'd say it was a mild case of salt...air at least. The underchassis
condition is a function of it's greater protection. The parts exposed
to the air look extensively (although not severely) corroded. If it
were just plain humidity and age, the underside would probably be similar.

jak

>
> Jim Mueller wrote:
>> Love the speaker grill!
>>
>> It looks like this has more problems than salt spray. What is the
>> inside like?
>>
>> Have fun with it.
>>
>
>
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